The following chapters in DeJong's Textbook "Neurological Examination" are recommended readings prior to the module Motor Systems as taught by Prof. Dr. Frederick Robert Carrick.

Chapter 11 Ocular Nerves

Chapter 26 Function of the Motor Systems

Chapter 27 Motor Strength and Power

Chapter 31 Abnormal Movements

The following references were utilized by Prof. Dr. Frederick Carrick in the preperation of his lecture for the Motor System of human kind.

 

1. Ackles, P. K.; Cook, K. G. Stimulus probability and event-related potentials of the

brain in 6-month-old human infants: a parametric study. Int-J-Psychophysiol.

1998 Jul; 29(2): 115-43; ISSN: 0167-8760.

NETHERLANDS. The effects of a priori stimulus probability and local-stimulus

sequences on the Nc, NSW and Pc components of the event-related brain

potentials were studied in six groups of 6-month-old human infants. Predictions

from memory, expectancy and attentional accounts of the Nc, NSW and Pc

components were examined using an infant-control oddball paradigm in which

visual stimuli were presented across groups, at 0.90/0.10, 0.80/0.20, 0.70/0.30,

0.60/0.40, 0.50/0.50 (alternation) and 0.50/0.50 (random) probabilities. The main

results indicated that stimulus probabilities and local-stimulus sequences affected

Nc amplitude and latency, NSW amplitude but not the Pc component. Concurrent

visual fixation performance was also found to be influenced by stimulus

probabilities. The results were discussed in terms of the predictions from

memory, expectancy and attentional accounts of the infant late components.

2. Afanas'ev, S. V.; Tolkunov, B. F.; Orlov, A. A.; Selezneva, E. V. Collective responses

of neostriatal (putamen) neurons during alternative behavior in monkeys.

Neurosci-Behav-Physiol. 1998 May; 28(3): 231-7; ISSN: 0097-0549.

UNITED-STATES. A monkey (Macaca nemestrina) was trained to perform a

behavioral program consisting of the selection and execution of a defined sequence

of actions according to a visual conditioned signal. Discriminant analysis was used

to evaluate the parameters of the collective activity of six simultaneously recorded

putamen neurons. The collective activity of the neurons showed significant

differences associated with execution by the monkey of left- and right-sided tasks.

These differences were seen to be quite consistent in different groups of neurons.

Despite the fact that putamen neurons were involved in the performance of nine

separately analyzed fragments of the program, differences were seen in two of

these: at the moment of taking the decision relating to the direction of movement,

and after its completion when a signal indicating the completed result was

presented, independently of whether the animal selected the side for the action

correctly or incorrectly. In the case of erroneous decisions, the response mosaic

differed from that obtained for correct decisions; however, differences due to

previously taken decisions regarding the side of action were preserved. These

differences were greater at the point of program completion than at the moment of

deciding the direction of movement.

3. Ahonen, J. P.; Jehkonen, M.; Dastidar, P.; Molnar, G.; Hakkinen, V. Cortical silent

period evoked by transcranial magnetic stimulation in ischemic stroke.

Electroencephalogr-Clin-Neurophysiol. 1998 Jun; 109(3): 224-9; ISSN: 0013-

4694.

IRELAND. OBJECTIVES: Transcranial magnetic stimulation (TMS) of the

motor cortex produces motor evoked potentials (MEPs). Besides this excitatory

response, TMS has inhibitory effects. When TMS is performed during voluntary

muscle contraction, the MEP is followed by a pause in electromyographic activity

(cortical silent period, SP). The aim of this study was to evaluate the clinical

usefulness of the SP. METHODS: We studied SP changes in 50 patients with

acute hemispheric brain infarction. A stimulator with a round coil and a fixed

intensity of 90% of maximum was used to evoke MEPs. RESULTS: SP was

elicited on the affected side in 29 of the 50 patients. The mean SP duration was

markedly longer on the affected side in the patient group. There were no

significant differences between left and right sides in the means of the MEP

amplitude ratio (amplitude related to corresponding amplitudes to peripheral

electric stimulation) and MEP latencies in the patient group. Prolonged SP was

found in 25 of the 29 patients (86%) whereas only 4 (14%) had abnormalities in

MEP latency or amplitude ratio. The mean SP duration was significantly

prolonged also in a subgroup of 14 patients with normal hand function.

CONCLUSIONS: The SP measurement is an easily performed and sensitive

method to detect even subclinical disturbances in motor system function in

ischemic stroke.

4. Airapetiants, M. G.; Levshina, I. P.; Nozdracheva, L. V.; Shuikin, N. N. [The action

of the neurotoxin AF64A on the reactions of neuroticized rats]. Deistvie

neirotoksina AF64A na reaktsii nevrotizirovannykh krys. Zh-Vyssh-Nerv-Deiat-

Im-I-P-Pavlova. 1998 May; 48(3): 534-40; ISSN: 0044-4677.

RUSSIA. The effects of intracerebroventricular administration of ethylholine

aziridinum ion (AF64A) were studied in neuroticized male Wistar rats. The

cholinotoxin was bilaterally injected in the dose of 3 nmol. AF64A produced a

significant decrease in arterial pressure and activity of respiratory enzymes

succinate dehydrogenase and NADH-dehydrogenase in hippocampus and motor

cortex. Increase in the local blood flow in the hippocampus and motor cortex had a

compensatory character.. EC 1.3.99.1; EC 1.6.99.3; 0; 0; 62-49-7; 63918-37-6.

5. Anastasopoulos, D.; Haslwanter, T.; Fetter, M.; Dichgans, J. Smooth pursuit eye

movements and otolith-ocular responses are differently impaired in cerebellar

ataxia. Brain. 1998 Aug; 121( Pt 8): 1497-505; ISSN: 0006-8950.

ENGLAND. Horizontal and vertical smooth pursuit was compared with otolith-

ocular responses in 11 patients with cerebellar ataxia and 21 normal subjects using

three-dimensional magnetic search coil eye movement recordings. Otolith-ocular

responses were investigated during off-vertical axis rotation. This stimulus

induces nystagmus consisting of the exponentially decaying canalicular response,

and an eye-velocity modulation and offset which arise from the excitation of the

otoliths by the gravity vector, which lasts as long as the rotation continues.

Otolith-ocular reflexes are intimately interrelated with visual tracking when real

targets are viewed during linear motion. The responses of both the translational

vestibulo-ocular reflex and the pursuit system have been shown to be linearly

dependent on the inverse of the viewing distance, so that a common central

pathway for the two systems has been suggested, probably travelling through the

cerebellum. Thus, the aim of the study was to evaluate to what extent these

reflexes are disturbed in cerebellar disease. The results confirm the earlier notion

that in normal subjects pursuit performance is better for horizontal than for

vertical tracking, and that it is better for upward than for downward tracking. This

pattern is also found in patients. In addition, smooth pursuit performance is

clearly degraded in patients, but the modulation of eye-velocity during off-vertical

axis rotation is enhanced. Since the amount of this enhancement does not correlate

with the amount of pursuit impairment, degradation of smooth pursuit and

pathological enhancement of otolith-ocular responses seem to be independent

effects of cerebellar degeneration. Thus, the increase in the otolith-ocular response

in patients cannot be attributed to adaptational mechanisms trying to overcome

the smooth pursuit deficiency; it is more likely to represent pathological

disinhibition of otolith derived responses. The absence of compensatory eye-

velocity offset during off-vertical axis rotation may reflect the fact that in patients

the otolith signals are not utilized in computations thought to be important for

spatial orientation mechanisms arising from the interaction of vestibular, visual

and somatosensory signals.

6. Anderson, R. W.; Keller, E. L.; Gandhi, N. J.; Das, S. Two-dimensional saccade-

related population activity in superior colliculus in monkey. J-Neurophysiol.

1998 Aug; 80(2): 798-817; ISSN: 0022-3077.

UNITED-STATES. The two-dimensional distribution of population activity in

the superior colliculus (SC) during saccadic eye movements in the monkey was

estimated using radial basis functions. To make these ensemble activity estimates,

cells in the deeper layers of the SC were recorded over much of the rostrocaudal

(caudal to 3.8 mm from the rostral tip), mediolateral extent of this structure. The

dynamic movement field of each cell was determined at 2-ms intervals around the

time of saccades for a wide variety of horizontal and oblique movements.

Collicular neurons were divided into partially overlapping dorsal and ventral cell

layers on the basis of recorded depth in SC. The pattern of presaccadic activity

was used as an additional discriminant to sort the cells in the two layers into

separate burst (dorsal) and buildup (ventral) cell classes. Rostrocaudal and

medioventral cell location on the colliculus was estimated from the optimal target

vector for a cell's visual response rather than from the optimal motor vector. The

former technique was more reliable for locating some buildup neurons because it

produced locations that compared better with the locations suggested by electrical

stimulation. From the movement field data and from the estimates of each cell's

anatomic location, a similar algorithm was used to compute the two-dimensional

population activity in the two layers of the SC during horizontal and oblique

saccades. A subset of the sample of neurons, located near the horizontal meridian

of the SC, first was used to compute one-dimensional dynamic population

activity estimates for horizontal saccades to allow partial comparison to previous

studies. Statistical analyses on the one-dimensional data were limited to saccades

of </=20 degrees. The analyses indicated that while there was a small rostrally

directed shift in the center of gravity of the distributed activity in the buildup cell

layer, there was little support for the theory of a systematic rostrally directed

spread of the leading edge of the activity. The two-dimensional results extend the

previous one-dimensional estimates of collicular activity during saccades.

Discharge in the burst layer was invariant in size for all saccade vectors and

symmetrically arranged about a center of gravity that did not move during

saccades. The size of the active area in the buildup layer grew modestly with

saccade amplitude, whereas the distribution of activity was skewed toward the

rostral end of the SC for saccades larger than 10 degrees. There was a small, but

consistent shift in the center of gravity of the two-dimensional activity that was

directed along the horizontal meridian (for horizontal movements) or an oblique

meridian (for oblique movements) of the SC. However, the spread of activity

during a saccade was as large or larger in the mediolateral direction as it was in the

rostral direction. The results indicate that changes in activity occur in an extended

zone on the SC, and in all directions but caudal, in the buildup layer during

saccades and do not support the idea of a rostrally directed spread of activity as a

dynamic control mechanism for saccades. Our results and those of previous

investigators of collicular population activity may be limited by stationarity

concerns in that the cells used to estimate population activity were recorded in

several monkeys over an extended period of time to obtain a sufficient spatial

sample.

7. Anderson, R. W.; Keller, E. L.; Gandhi, N. J.; Das, S. Two-dimensional saccade-

related population activity in superior colliculus in monkey. J-Neurophysiol.

1998 Aug; 80(2): 798-817; ISSN: 0022-3077.

UNITED-STATES. The two-dimensional distribution of population activity in

the superior colliculus (SC) during saccadic eye movements in the monkey was

estimated using radial basis functions. To make these ensemble activity estimates,

cells in the deeper layers of the SC were recorded over much of the rostrocaudal

(caudal to 3.8 mm from the rostral tip), mediolateral extent of this structure. The

dynamic movement field of each cell was determined at 2-ms intervals around the

time of saccades for a wide variety of horizontal and oblique movements.

Collicular neurons were divided into partially overlapping dorsal and ventral cell

layers on the basis of recorded depth in SC. The pattern of presaccadic activity

was used as an additional discriminant to sort the cells in the two layers into

separate burst (dorsal) and buildup (ventral) cell classes. Rostrocaudal and

medioventral cell location on the colliculus was estimated from the optimal target

vector for a cell's visual response rather than from the optimal motor vector. The

former technique was more reliable for locating some buildup neurons because it

produced locations that compared better with the locations suggested by electrical

stimulation. From the movement field data and from the estimates of each cell's

anatomic location, a similar algorithm was used to compute the two-dimensional

population activity in the two layers of the SC during horizontal and oblique

saccades. A subset of the sample of neurons, located near the horizontal meridian

of the SC, first was used to compute one-dimensional dynamic population

activity estimates for horizontal saccades to allow partial comparison to previous

studies. Statistical analyses on the one-dimensional data were limited to saccades

of </=20 degrees. The analyses indicated that while there was a small rostrally

directed shift in the center of gravity of the distributed activity in the buildup cell

layer, there was little support for the theory of a systematic rostrally directed

spread of the leading edge of the activity. The two-dimensional results extend the

previous one-dimensional estimates of collicular activity during saccades.

Discharge in the burst layer was invariant in size for all saccade vectors and

symmetrically arranged about a center of gravity that did not move during

saccades. The size of the active area in the buildup layer grew modestly with

saccade amplitude, whereas the distribution of activity was skewed toward the

rostral end of the SC for saccades larger than 10 degrees. There was a small, but

consistent shift in the center of gravity of the two-dimensional activity that was

directed along the horizontal meridian (for horizontal movements) or an oblique

meridian (for oblique movements) of the SC. However, the spread of activity

during a saccade was as large or larger in the mediolateral direction as it was in the

rostral direction. The results indicate that changes in activity occur in an extended

zone on the SC, and in all directions but caudal, in the buildup layer during

saccades and do not support the idea of a rostrally directed spread of activity as a

dynamic control mechanism for saccades. Our results and those of previous

investigators of collicular population activity may be limited by stationarity

concerns in that the cells used to estimate population activity were recorded in

several monkeys over an extended period of time to obtain a sufficient spatial

sample.

8. Angelaki, D. E. Three-dimensional organization of otolith-ocular reflexes in rhesus

monkeys. III. Responses To translation. J-Neurophysiol. 1998 Aug; 80(2): 680-

95; ISSN: 0022-3077.

UNITED-STATES. The three-dimensional (3-D) properties of the translational

vestibulo-ocular reflexes (translational VORs) during lateral and fore-aft

oscillations in complete darkness were studied in rhesus monkeys at frequencies

between 0.16 and 25 Hz. In addition, constant velocity off-vertical axis rotations

extended the frequency range to 0.02 Hz. During lateral motion, horizontal

responses were in phase with linear velocity in the frequency range of 2-10 Hz.

At both lower and higher frequencies, phase lags were introduced. Torsional

response phase changed more than 180 degrees in the tested frequency range such

that torsional eye movements, which could be regarded as compensatory to "an

apparent roll tilt" at the lowest frequencies, became anticompensatory at all

frequencies above approximately 1 Hz. These results suggest two functionally

different frequency bandwidths for the translational VORs. In the low-frequency

spectrum (<<0.5 Hz), horizontal responses compensatory to translation are small

and high-pass-filtered whereas torsional response sensitivity is relatively

frequency independent. At higher frequencies however, both horizontal and

torsional response sensitivity and phase exhibit a similar frequency dependence,

suggesting a common role during head translation. During up-down motion,

vertical responses were in phase with translational velocity at 3-5 Hz but phase

leads progressively increased for lower frequencies (>90 degrees at frequencies

<0.2 Hz). No consistent dependence on static head orientation was observed for

the vertical response components during up-down motion and the horizontal and

torsional response components during lateral translation. The frequency response

characteristics of the translational VORs were fitted by "periphery/brain stem"

functions that related the linear acceleration input, transduced by primary otolith

afferents, to the velocity signals providing the input to the velocity-to-position

neural integrator and the oculomotor plant. The lowest-order, best-fit

periphery/brain stem model that approximated the frequency dependence of the

data consisted of a second order transfer function with two alternating poles (at

0.4 and 7.2 Hz) and zeros (at 0.035 and 3.4 Hz). In addition to clearly

differentiator dynamics at low frequencies (less than approximately 0.5 Hz), there

was no frequency bandwidth where the periphery/brain stem function could be

approximated by an integrator, as previously suggested. In this scheme, the

oculomotor plant dynamics are assumed to perform the necessary high-frequency

integration as required by the reflex. The detailed frequency dependence of the

data could only be precisely described by higher order functions with

nonminimum phase characteristics that preclude simple filtering of afferent inputs

and might be suggestive of distributed spatiotemporal processing of otolith signals

in the translational VORs.

9. Annoni, G.; Pegna, A.; Michel, C.; Estade, M.; Landis, T. Motor perseverations: a

function of the side and the site of a cerebral lesion. Eur-Neurol. 1998 Aug; 40(2):

84-90; ISSN: 0014-3022.

SWITZERLAND. Motor perseverations are commonly thought to be a sign of

frontal lobe lesions, although they may also occur following lesions outside the

frontal lobes. Moreover, differences in the type and frequency of motor

perseverations between the two cerebral hemispheres have been suggested.

Recurrent perseverations (repetition of a previous response to a subsequent

stimulus) and continuous perseverations (abnormal prolongation of a current

activity) are two different aspects of motor intentional disorders. The former have

been associated with left hemispheric lesions, and the latter with right hemispheric

lesions. To test this hypothesis, we examined 42 patients with single cerebral

lesions of different locations: 22 right hemispheric (7 frontal and 15 extrafrontal)

and 20 left hemispheric lesions (8 frontal and 12 extrafrontal), and healthy

controls with a graphic task, allowing for analysis of these two types of motor

perseverations. We found that (i) both types of perseverations increased

significantly for all groups of patients compared to normal controls, except for

recurrent perseverations in patients with right posterior lesions, (ii) there was no

significant dissociation between the type of perseverations and the side of lesions,

and (iii) there was a significant interaction between the type of perseveration,

frontal versus extrafrontal location, and the side of a lesion, which is based on the

tendency for recurrent perseverations to be increased in left posterior and right

frontal lesions, and decreased in left frontal and right posterior lesions, as

compared to continuous perseverations. These findings cast doubt about the

predominant role of the frontal lobes for motor perseverations, but support the

idea of hemispheric specialization in motor control which is, however, more

complex than previously thought.

10. Aranyi, Z.; Mathis, J.; Hess, C. W.; Rosler, K. M. Task-dependent facilitation of

motor evoked potentials during dynamic and steady muscle contractions. Muscle-

Nerve. 1998 Oct; 21(10): 1309-16; ISSN: 0148-639X.

UNITED-STATES. Task-dependent differences in the facilitation of motor

evoked potentials (MEPs) following cortex stimulation were studied in a proximal

(deltoid) and a distal muscle (abductor digiti minimi; ADM) in 23 healthy subjects

during both dynamic and steady contractions of the target muscle under isometric

and under nonisometric conditions. In the deltoid, MEP amplitudes were

significantly greater if stimulation was performed during dynamic contractions

than during steady contractions, despite equal background electromyographic

levels just prior to the stimulus. The same task-specific extra facilitation of deltoid

MEP amplitudes was also found with magnetic stimulation of the brain stem

instead of the cortex in 3 subjects. In the ADM, no such task-dependent extra

facilitation of MEPs during dynamic contractions was found. It is concluded that

in the deltoid, during dynamic contractions, a greater proportion of the spinal

motoneurons is close to depolarization threshold (greater "subliminal fringe")

whereas the number of firing motoneurons is similar to that during steady

contraction. The lack of task-dependent extra facilitation of MEPs in the ADM is

explained by the predominant recruitment principle for force gradation in small

hand muscles, which is in contrast to the predominant frequency principle used in

proximal muscles.

11. Atkinson, G.; Speirs, L. Diurnal variation in tennis service. Percept-Mot-Skills. 1998

Jun; 86(3 Pt 2): 1335-8; ISSN: 0031-5125.

UNITED-STATES. With informed consent, 6 competitive tennis players

performed alternate 15 "first" (emphasis-speed) serves and 15 "second"

(emphasis-accuracy) serves at 09:00, 14:00 and 18:00 hours. Serve velocity was

measured by the digitisation of video footage of each serve. The Hewitt Tennis

Achievement Test was employed to measure the accuracy of serve. The amount

of spin imparted on the ball was not measured. First serves were at all times of

day faster than second serves. First serves were faster but least accurate at 18:00

hours, the time of day that body temperature and grip strength were highest. At

09:00 hours, first serves were just as accurate as second serves, even though

velocity of first serves was higher. No effects for time of day were found for the

speed and accuracy of second serves. These results indicate that time of day does

affect the performance of tennis serves in a way that suggest a nonlinear

relationship between velocity and accuracy.

12. Aurora, S. K.; Welch, K. M. Brain excitability in migraine: evidence from transcranial

magnetic stimulation studies. Curr-Opin-Neurol. 1998 Jun; 11(3): 205-9; ISSN:

1350-7540.

UNITED-STATES. Central neuronal hyperexcitability is proposed to be the

putative basis for the physiologic disturbances in migraine. Because there are no

structural disturbances in migraine, only physiologic studies can provide insight

into the underlying mechanisms. Recently, transcranial magnetic stimulation has

been developed as a valuable research tool and can be used to study brain function

noninvasively. This article is a review of the studies done in migraine using

transcranial magnetic stimulation.

13. Aurora, S. K.; Welch, K. M. Brain excitability in migraine: evidence from transcranial

magnetic stimulation studies. Curr-Opin-Neurol. 1998 Jun; 11(3): 205-9; ISSN:

1350-7540.

UNITED-STATES. Central neuronal hyperexcitability is proposed to be the

putative basis for the physiologic disturbances in migraine. Because there are no

structural disturbances in migraine, only physiologic studies can provide insight

into the underlying mechanisms. Recently, transcranial magnetic stimulation has

been developed as a valuable research tool and can be used to study brain function

noninvasively. This article is a review of the studies done in migraine using

transcranial magnetic stimulation.

14. Ay, H.; Buonanno, F. S.; Price, B. H.; Le, D. A.; Koroshetz, W. J. Sensory alien hand

syndrome: case report and review of the literature. J-Neurol-Neurosurg-

Psychiatry. 1998 Sep; 65(3): 366-9; ISSN: 0022-3050.

ENGLAND. An 81 year old right handed woman developed a left alien hand

syndrome characterised by involuntary movements of choking and hitting the

face, neck, and shoulder. The patient showed multiple disorders of primary

sensation, sensory processing, hemispatial attention, and visual association, as

well as a combination of sensory, optic, and cerebellar ataxia (triple ataxia) of the

left arm in the absence of motor neglect or hemiparesis. Imaging studies disclosed

subacute infarction in the right thalamus, hippocampus, inferior temporal lobes,

splenium of corpus callosum, and occipital lobe due to right posterior cerebral

artery occlusion. This rare syndrome should be considered as a "sensory" or

"posterior" form of the alien hand syndrome, to be distinguished from the "motor"

or "anterior" form described more commonly.

15. Bair, W.; O'Keefe, L. P. The influence of fixational eye movements on the response of

neurons in area MT of the macaque. Vis-Neurosci. 1998 Jul; 15(4): 779-86; ISSN:

0952-5238.

ENGLAND. We analyzed the relationship between eye movements and neuronal

responses recorded from area MT in alert monkeys trained to maintain visual

fixation during the presentation of moving patterns. The monkeys made small

saccades which moved the eyes with velocities that spanned the sensitivity range

of MT neurons. The saccades evoked changes in the neuronal response that

depended upon (1) the level of stimulus-evoked activity amidst which the saccade

occurred and (2) the direction of the saccade relative to the preferred direction of

the neuron. Most notably, saccades were able to suppress stimulus-evoked

activity when they caused retinal image flow that opposed the neuron's preference

and were able to elicit a response or enhance weak activity when they caused flow

in the neuron's preferred direction. On average, the disturbance lasted 40 ms

beginning about 40 ms following saccade onset. Using these parameters, we

simulated synthetic spike trains from an imaginary pair of similarly tuned neurons

and determined that the interneuronal correlation due to saccades should be

negligible at all but the lowest ongoing firing rates. This conclusion was supported

from our data by the observation that response variance for single MT spike

trains was not measurably reduced during periods of stable gaze compared to

periods when eye movement exceeded a stability criterion (0.1 deg during 0.5 s).

While the intrusions caused by saccades are too short-lived and infrequent to

account for the variability of MT neuronal response (counter to the finding in V1

of Gur et al., 1997), the clear directional signal that they carry in area MT

suggests that motion perception is not blocked during saccades by suppression at

early stages in the visual pathway.

16. Bair, W.; O'Keefe, L. P. The influence of fixational eye movements on the response of

neurons in area MT of the macaque. Vis-Neurosci. 1998 Jul; 15(4): 779-86; ISSN:

0952-5238.

ENGLAND. We analyzed the relationship between eye movements and neuronal

responses recorded from area MT in alert monkeys trained to maintain visual

fixation during the presentation of moving patterns. The monkeys made small

saccades which moved the eyes with velocities that spanned the sensitivity range

of MT neurons. The saccades evoked changes in the neuronal response that

depended upon (1) the level of stimulus-evoked activity amidst which the saccade

occurred and (2) the direction of the saccade relative to the preferred direction of

the neuron. Most notably, saccades were able to suppress stimulus-evoked

activity when they caused retinal image flow that opposed the neuron's preference

and were able to elicit a response or enhance weak activity when they caused flow

in the neuron's preferred direction. On average, the disturbance lasted 40 ms

beginning about 40 ms following saccade onset. Using these parameters, we

simulated synthetic spike trains from an imaginary pair of similarly tuned neurons

and determined that the interneuronal correlation due to saccades should be

negligible at all but the lowest ongoing firing rates. This conclusion was supported

from our data by the observation that response variance for single MT spike

trains was not measurably reduced during periods of stable gaze compared to

periods when eye movement exceeded a stability criterion (0.1 deg during 0.5 s).

While the intrusions caused by saccades are too short-lived and infrequent to

account for the variability of MT neuronal response (counter to the finding in V1

of Gur et al., 1997), the clear directional signal that they carry in area MT

suggests that motion perception is not blocked during saccades by suppression at

early stages in the visual pathway.

17. Barry, J. C.; Backes, A. [Measuring the effect of eyeglasses on determination of

squint angle with Purkinje reflexes and the prism cover test]. Messungen zum

Einfluss von Brillenglasern auf die Bestimmung des Schielwinkels mit Purkinje-

Reflexen und mit dem Prismenabdecktest. Klin-Monatsbl-Augenheilkd. 1998 Apr;

212(4): 234-9; ISSN: 0023-2165.

GERMANY. BACKGROUND: The alternating prism and cover test is the

conventional test for the measurement of the angle of strabismus. The error

induced by the prismatic effect of glasses is typically about 27-30%/10 D.

Alternatively, the angle of strabismus can be measured with methods based on

Purkinje reflex positions. This study examines the differences between three such

options, taking into account the influence of glasses. MATERIALS AND

METHODS: The studied system comprised the eyes with or without glasses, a

fixation object and a device for recording the eye position: in the case of the

alternate prism and cover test, a prism bar was required; in the case of a Purkinje

reflex based device, light sources for generation of reflexes and a camera for the

documentation of the reflex positions were used. Measurements performed on

model eyes and computer ray traces were used to analyze and compare the

options. RESULTS: When a single corneal reflex is used, the misalignment of the

corneal axis can be measured; the error in this measurement due to the prismatic

effect of glasses was 7.6%/10 D, the smallest found in this study. The individual

Hirschberg ratio can be determined by monocular measurements in three gaze

directions. CONCLUSIONS: The angle of strabismus can be measured with

Purkinje reflex based methods if the fundamental differences between these

methods and the alternate prism and cover test, and if the influence of glasses and

other sources of error are accounted for.

18. Basso, M. A.; Wurtz, R. H. Modulation of neuronal activity in superior colliculus by

changes in target probability. J-Neurosci. 1998 Sep 15; 18(18): 7519-34; ISSN:

0270-6474.

UNITED-STATES. Complex visual scenes require that a target for an impending

saccadic eye movement be selected from a larger number of possible targets. We

investigated whether changing the probability that a visual stimulus would be

selected as the target for a saccade altered activity of monkey superior colliculus

(SC) neurons in two experiments. First, we changed the number of possible

targets on each trial. Second, we kept the visual display constant and presented a

single saccade target repeatedly so that target probability was established over

time. Buildup neurons in the SC, those with delay period activity, showed a

consistent reduction in activity as the probability of the saccade decreased,

independent of the visual stimulus configuration. Other SC neurons, fixation and

burst, were largely unaffected by the changes in saccade target probability.

Because we had monkeys making saccades to many locations within the visual

field, we could examine activity associated with saccades outside of the movement

field of neurons. We found the activity of buildup neurons to be similar across the

SC, before the target was identified, and reduced when the number of possible

targets increased. The results of our experiments are consistent with a role for this

activity in establishing a motor set. We found, consistent with this interpretation,

that the activity of these neurons was predictive of the latency of a saccadic eye

movement and not other saccade parameters such as end point or peak velocity.

19. Basso, M. A.; Wurtz, R. H. Modulation of neuronal activity in superior colliculus by

changes in target probability. J-Neurosci. 1998 Sep 15; 18(18): 7519-34; ISSN:

0270-6474.

UNITED-STATES. Complex visual scenes require that a target for an impending

saccadic eye movement be selected from a larger number of possible targets. We

investigated whether changing the probability that a visual stimulus would be

selected as the target for a saccade altered activity of monkey superior colliculus

(SC) neurons in two experiments. First, we changed the number of possible

targets on each trial. Second, we kept the visual display constant and presented a

single saccade target repeatedly so that target probability was established over

time. Buildup neurons in the SC, those with delay period activity, showed a

consistent reduction in activity as the probability of the saccade decreased,

independent of the visual stimulus configuration. Other SC neurons, fixation and

burst, were largely unaffected by the changes in saccade target probability.

Because we had monkeys making saccades to many locations within the visual

field, we could examine activity associated with saccades outside of the movement

field of neurons. We found the activity of buildup neurons to be similar across the

SC, before the target was identified, and reduced when the number of possible

targets increased. The results of our experiments are consistent with a role for this

activity in establishing a motor set. We found, consistent with this interpretation,

that the activity of these neurons was predictive of the latency of a saccadic eye

movement and not other saccade parameters such as end point or peak velocity.

20. Baunez, C.; Salin, P.; Nieoullon, A.; Amalric, M. Impaired performance in a

conditioned reaction time task after thermocoagulatory lesions of the fronto-

parietal cortex in rats. Cereb-Cortex. 1998 Jun; 8(4): 301-9; ISSN: 1047-3211.

UNITED-STATES. The present study examined whether cortical damage in rats

may disrupt the integrative processes and motor control involved in the

performance of a reaction time (RT) task. To investigate the nature of the deficits

in the conditioned task, rats were subjected, after learning, to a coagulation of pia

brain surface of varying extent, including the frontal and parietal cortical areas.

They were then tested daily for over one month. The behavioural task required

the rats to hold a lever down during a variable and random delay and react quickly

to the onset of a visual cue by releasing the lever within a RT limit for food

reinforcement. Extensive bilateral cortical lesions had no effect on spontaneous

motor activity, but severely impaired RT performance. Latencies to release the

lever after the cue were dramatically increased during the first postoperative

sessions and gradually returned to baseline levels within 3 weeks, whereas less

dramatic but long-lasting increase in premature responding (anticipatory response

before the visual cue) was observed throughout the testing sessions. More

restricted lesions to the frontoparietal cortex produced a similar pattern of

incorrect responding with a faster recovery of delayed responses and a strong

deficit in premature responding. The major effects of lesions confined to the

rostral pole of the frontal cortex were observed on premature responding,

however. The present results demonstrate that the impairment in movement

initiation is rapidly recovered within 2-3 weeks even after extensive

thermocoagulatory lesions of the frontal and parietal areas. This recovery suggests

the involvement of adaptive processes developing progressively and probably

reflecting the remarkable synaptic plasticity of the extrapyramidal motor output.

In contrast, the long-lasting increase in premature responding, supposed to reflect

some attentional deficits, may produce anatomofunctional long-term

disorganization of subcortical structures such as the basal ganglia. Interestingly

enough, these results show that the rat neocortex supports functions very similar

to those of primates and provide a good model for studying these higher functions

in operant motor procedures that require prior associative learning and

appropriate motor coordination.

21. Bernasconi, O.; Borruat, F. X. [Unilateral accommodation spasm: a diagnostic

pitfall!]. Spasme d'accommodation unilateral: un piege diagnostic! Klin-

Monatsbl-Augenheilkd. 1998 May; 212(5): 392-3; ISSN: 0023-2165.

GERMANY. BACKGROUND: Accommodation-convergence spasm (spasm of

the near reflex) is usually bilateral, resulting in increased myopia, convergence, and

miosis. Unilateral spasm of accommodation has rarely been reported. PATIENTS:

We investigated three females (age range 10-19 years) referred for investigations of

retrobulbar optic neuritis (2 cases) and decompensated esophoria (1 case).

RESULTS: They all presented unilateral spasm of accommodation with visual

loss due to increased myopia (-3.5 to -11.75 diopters). Apart from that, results of

neuro-ophthalmological examination were normal. CONCLUSIONS: Unilateral

accommodation spasm is rare and can mimic retrobulbar optic neuritis and

convergent strabismus. The three components of the accommodation-convergence

spasm may not always be present simultaneously. Recognizing such an entity is

important to prevent the patient from useless, costful and potentially harmful

investigations.

22. Bernasconi, O.; Klainguti, G. [Is there a primary and secondary torsion deviation in

paralysis of the grand oblique muscle?]. Peut-on parler de deviation torsionnelle

primaire et secondaire dans la paralysie du grand oblique? Klin-Monatsbl-

Augenheilkd. 1998 May; 212(5): 286-8; ISSN: 0023-2165.

GERMANY. BACKGROUND: An extraocular muscle palsy is conventionally

characterized by a deviation of the visual axes, this being greater when measured

with the affected eye fixing. By definition and illustrating Hering's law, this

secondary angle of deviation is greater than the primary one, measured with the

sound eye fixing. We present here a comparative study of the amount of

subjective excyclodeviation measured in patients suffering from IVth nerve palsy,

with the sound or affected eye fixing. METHODS: Two groups of patients were

entered into the study: Group 1 (N = 54) for superior oblique palsies studied

retrospectively and Group 2 (N = 14), for a prospective study of those recently

acquired (post-traumatic) and followed over 6 months. In both groups,

measurements were made at two stages, early (1 to 7 weeks after onset) and late

(4 to 6 months later). RESULTS: In both groups, the majority of cases showed a

greater secondary torsional deviation, the difference between this and the primary

deviation lessening on late stage measurements. CONCLUSION: In both groups,

the difference between primary and secondary torsional deviation was not

statistically significant.

23. Bernhardt, J.; Ellis, P.; Denisenko, S.; Hill, K. Changes in balance and locomotion

measures during rehabilitation following stroke. Physiother-Res-Int. 1998; 3(2):

109-22; ISSN: 1358-2267.

ENGLAND. BACKGROUND AND PURPOSE: This study aimed to examine

the utility of a number of measures of balance and locomotion for the purpose of

measuring change in a group of stroke patients undergoing in-patient

rehabilitation. The aim was to select a core group of measures based on empirical

evidence of usefulness rather than personal preference. METHODS: Twenty-nine

stroke patients undergoing in-patient rehabilitation (mean age 71.8 +/- 10.5 years;

66% male) participated in the study. A prospective design was utilized with

repeated measurement undertaken at four, six and eight weeks post-stroke. Static

standing, the Clinical Test of Sensory Interaction of Balance (CTSIB) (Shumway-

Cook & Horak, 1986), functional reach (FR), repetitive reach (RR), step test

(ST), gait velocity, stride length and the Motor Assessment Scale (Carr et al.,

1985) (walking item) were assessed at each interval. RESULTS: All measures of

dynamic balance showed significant change over the four-week measurement

period (p < 0.0036). Factor analysis identified two factors which grouped tests

into static and dynamic, with a trend towards a third factor incorporating bipedal

dynamic tests. Tests of static balance suffered from ceiling effects, whereas

dynamic tests of balance and gait suffered from floor effects. Dynamic tests were

more responsive (Standardized Response Measure (SRM) > 0.75) to change over

the rehabilitation period than static tests. CONCLUSIONS: The findings suggest

that a clinically useful and responsive balance and mobility test battery should

include one component of the CTSIB (Shumway-Cook & Horak, 1986), RR (step

stance), ST and gait velocity.

24. Birmingham, T. B.; Kramer, J. F.; Inglis, J. T.; Mooney, C. A.; Murray, L. J.; Fowler,

P. J.; Kirkley, S. Effect of a neoprene sleeve on knee joint position sense during

sitting open kinetic chain and supine closed kinetic chain tests. Am-J-Sports-

Med. 1998 Jul; 26(4): 562-6; ISSN: 0363-5465.

UNITED-STATES. The primary objective of the present study was to compare

the effect of a neoprene sleeve on knee joint position sense during a sitting open

kinetic chain test and a supine closed kinetic chain test. Young (24 +/- 2 years

old), healthy subjects (18 men and 18 women) performed knee joint angle

replication tests during open kinetic chain knee extension (sitting) and closed

kinetic chain leg press (supine with an axial load of 15% body weight) before and

after application of a neoprene sleeve over the dominant knee. The improvement

in ability to replicate joint angles after application of the sleeve (sleeve effect) was

significantly less during the supine closed kinetic chain test (0.3 degree +/- 1.4

degrees) than during the sitting open kinetic chain test (1.2 degrees +/- 1.1

degrees). The sleeve effect was inversely related to subjects' performance without

the sleeve during both the sitting open kinetic chain and supine closed kinetic

chain tests, suggesting that some people may derive greater benefit from the sleeve

than others. Although the sleeve effects were small, particularly during the supine

closed kinetic chain test, 72% of subjects felt that the sleeve improved their

overall test performance. Future research is needed to establish the functional

relevance of the small sleeve effects observed and to identify the characteristics of

people who might derive greatest benefit from sleeve use.. 9010-98-4.

25. Bjorklund, D. F.; Brown, R. D. Physical play and cognitive development: integrating

activity, cognition, and education [comment]. Child-Dev. 1998 Jun; 69(3): 604-6;

ISSN: 0009-3920.

Note: Comment on: Child Dev 1998 Jun;69(3):577-98.

UNITED-STATES. We propose that humans may have evolved a special

sensitivity to certain types of social information during rough-and-tumble play

that facilitates social cognition. The cognitive benefits of physical play are

described as providing a break from demanding intellectual tasks, and are

hypothesized to be related to gender differences in spatial cognition.

26. Blakemore, S. J.; Goodbody, S. J.; Wolpert, D. M. Predicting the consequences of our

own actions: the role of sensorimotor context estimation. J-Neurosci. 1998 Sep

15; 18(18): 7511-8; ISSN: 0270-6474.

UNITED-STATES. During self-generated movement it is postulated that an

efference copy of the descending motor command, in conjunction with an internal

model of both the motor system and environment, enables us to predict the

consequences of our own actions (von Helmholtz, 1867; Sperry, 1950; von Holst,

1954; Wolpert, 1997). Such a prediction is evident in the precise anticipatory

modulation of grip force seen when one hand pushes on an object gripped in the

other hand (Johansson and Westling, 1984; Flanagan and Wing, 1933). Here we

show that self-generation is not in itself sufficient for such a prediction. We used

two robots to simulate virtual objects held in one hand and acted on by the other.

Precise predictive grip force modulation of the restraining hand was highly

dependent on the sensory feedback to the hand producing the load. The results

show that predictive modulation requires not only that the movement is self-

generated, but also that the efference copy and sensory feedback are consistent

with a specific context; in this case, the manipulation of a single object. We

propose a novel computational mechanism whereby the CNS uses multiple

internal models, each corresponding to a different sensorimotor context, to

estimate the probability that the motor system is acting within each context.

27. Blekher, T.; Christian, J. C.; Abel, L. A.; Yee, R. D. Influences of chorion type on

saccadic eye movements in twins. Invest-Ophthalmol-Vis-Sci. 1998 Oct; 39(11):

2186-90; ISSN: 0146-0404.

UNITED-STATES. PURPOSE: The influence of genetic and prenatal

environmental factors on characteristics of saccadic performance were evaluated in

young monozygotic (MZ) twins (8-19 years old) of known chorion type.

METHODS: Saccadic eye movements were recorded using an infrared system.

Saccadic latency, accuracy, and parameters of amplitude-peak velocity

exponential equation (main sequence) were quantified. RESULTS: Intraclass

correlations of saccadic parameters differed significantly from zero for

monochorionic and dichorionic MZ twins. The within-pair mean squares were

significantly less, and intraclass correlations were significantly higher in

monochorionic than in dichorionic twins for latency and were similar for other

saccadic parameters (accuracy, slope of main sequence, and peak velocity for 15

degrees saccades). CONCLUSIONS: These findings confirmed previous reports

that saccadic parameters of MZ twins are significantly correlated and indicated

that similarity of these parameters seen in MZ twins may be driven both by

genetic and by prenatal environmental factors.

28. Bohning, D. E.; Shastri, A.; Nahas, Z.; Lorberbaum, J. P.; Andersen, S. W.; Dannels,

W. R.; Haxthausen, E. U.; Vincent, D. J.; George, M. S. Echoplanar BOLD fMRI

of brain activation induced by concurrent transcranial magnetic stimulation.

Invest-Radiol. 1998 Jun; 33(6): 336-40; ISSN: 0020-9996.

UNITED-STATES. RATIONALE AND OBJECTIVES: The authors

demonstrate the feasibility of combining transcranial magnetic stimulation (TMS)

and functional magnetic resonance imaging (fMRI) inside an MR scanner to

noninvasively stimulate and image regional brain activity. METHODS:

Echoplanar blood oxygen level dependent (BOLD)-based fMRI studies of TMS

response were performed on three human volunteers inside a standard 1.5 T MR

scanner using independent computer control to interleave echoplanar image

acquisition and stimulation of right thumb primary motor cortex with a

nonferromagnetic TMS coil. RESULTS: Significant (P< 0.001) response was

observed in motor cortex under the TMS coil during stimulation compared to rest,

as well in auditory cortex, the latter presumably due to the loud "snap" when the

coil was pulsed. CONCLUSIONS: Concurrent TMS stimulation and echoplanar

BOLD fMRI imaging is possible. This method has potential for tracing neural

circuits with brain imaging, as well as investigating the effects of TMS.

29. Bondestam, M.; Amcoff, B. [Child health centers do not catch all preschool children

with problems. Child health services should co-operate with school health

services more closely]. BVC fangar inte alla forskolebarn med problem.

Barnhalsovard och skolhalsovard borde samarbeta tatare. Lakartidningen. 1998

Sep 16; 95(38): 4103-5; ISSN: 0023-7205.

SWEDEN.

30. Borruat, F. X.; Gianoli, F.; Maeder, P.; Bogousslavsky, J. [Skew deviation]. Skew

deviation. Klin-Monatsbl-Augenheilkd. 1998 May; 212(5): 289-90; ISSN: 0023-

2165.

GERMANY. BACKGROUND: Skew deviation is a vertical ocular misalignment

of prenuclear origin. Although well described in the literature, it is still probably

underdiagnosed. Natural history of skew deviation is not well described in the

literature. PURPOSE: To describe the clinical presentations, etiologies and follow-

up of skew deviation. METHODS: Retrospective study of 29 patients diagnosed

with skew deviation between 1993 and 1996. RESULTS: The commonest cause

was cerebrovascular accident (12/29) and the commonest localisation was

mesencephalic (9/29). Other causes included surgery (7/29), tumor (4/29), trauma

(3/29), degeneration (3/29), inflammatory (2/29), increased intracranial pressure

(1/29). Other localisations included cerebellum (5/29), ponto-mesencephalic

(3/29), and medulla (2/29). Vertical diplopia was always accompanied by other

neuro-ophthalmologic abnormalities. 69.2% (18/26) patients were totally

asymptomatic after 7.5 months. 30.8% (8/26) were still symptomatic (diplopia).

One patient required surgery, three patients were relieved with prisms, one

patient needed monocular occlusion. One patient died during follow-up and

precise data were lacking in two symptomatic patients. CONCLUSION: Skew

deviation is not so rare, 10% of the cases referred to us for diplopia in 3 years.

The diagnosis of skew deviation should be entertained when vertical diplopia

cannot be explained by pathology of extraocular muscles, peripheral or central

cranial nerve III or IV palsies, myasthenia, or orbital pathology. Prognosis for

recovery in patients with skew deviation is good. 70% will recover, after a median

time of 7.5 months. Surgery should be postponed at least for 12 months.

31. Bremmer, F.; Pouget, A.; Hoffmann, K. P. Eye position encoding in the macaque

posterior parietal cortex. Eur-J-Neurosci. 1998 Jan; 10(1): 153-60; ISSN: 0953-

816X.

FRANCE. In two previous studies, we had demonstrated the influence of eye

position on neuronal discharges in the middle temporal area, medial superior

temporal area, lateral intraparietal area and area 7A of the awake monkey

(Bremmer et al., 1997a,b). Eye position effects also have been found in visual

cortical areas V3A and V6 and even in the premotor cortex and the supplementary

eye field. These effects are generally discussed in light of a coordinate

transformation of visual signals into a non-retinocentric frame of reference. Neural

network studies dealing with the eye position effect succeeded in constructing

such non-retinocentric representations by using model neurones whose response

characteristics resembled those of 'real' neurones. However, to our knowledge,

response properties of real neurones never acted as input into these neural

networks. In the present study, we thus investigated whether, theoretically, eye

position could be estimated from the population discharge of the (previously)

recorded neurones and, if so, we intended to develop an encoding algorithm for the

position of the eyes in the orbit. The optimal linear estimator proved the

capability of the ensemble activity for determining correctly eye position. We

then developed the so-called subpopulation encoding of eye position. This

algorithm is based on the partition of the ensemble of neurones into two pairs of

subpopulations. Eye position is represented by the differences of activity levels

within each pair of subpopulations. Considering this result, encoding of the

location of an object relative to the head could easily be accomplished by

combining eye position information with the intrinsic knowledge about the retinal

location of a visual stimulus. Taken together, these results show that throughout

the monkey's visual cortical system information is available which can be used in a

fairly simple manner in order to generate a non-retinocentric representation of

visual information.

32. Breton, P.; Bizot, J. C.; Buee, J.; De, La Manche I. Brain neurotoxicity of Penitrem

A: electrophysiological, behavioral and histopathological study. Toxicon. 1998

Apr; 36(4): 645-55; ISSN: 0041-0101.

ENGLAND. The neurotoxicity of Penitrem A (PA) in rats was assessed against

neurophysiological, behavioral and histopathological parameters. Animals were

acutely given intracerebroventricular (22-45 mg) or intraperitoneal injections (0.5-

1.5 mg/kg) of PA. A typical trembling syndrome associated with PA was always

noted. Depending on the dose administered, animals may convulse and eventually

die (1-1.5 mg/kg). PA-induced transient alterations of the EEG involving an

increase in the frequency and voltage of electrical activity recorded from the

cerebral cortex. Hippocampal activity was not modified and some pathologic

activities may be recorded at the thalamus. Generally these EEG alterations

disappeared at d 3 after the injection and the animals progressively recovered.

However in the most severe cases, neuromotor disturbances were maintained at d

7 (rotarod test). Coronal sections of the brain at the striatal, thalamic,

hippocampal and pons levels mainly revealed that PA was able to induce dose

related injuries in the cerebellum with massive degeneration of Purkinje cells and a

significant vacuolization within the molecular layer. The neurotoxic mechanism

remains unclear. Action of the mycotoxin on the cerebello-thalamo-cortical tract is

discussed.. 0; 37203-49-9.

33. Brooke Wavell, K.; Athersmith, L. E.; Jones, P. R.; Masud, T. Brisk walking and

postural stability: A cross-sectional study in postmenopausal women.

Gerontology. 1998; 44(5): 288-92; ISSN: 0304-324X.

SWITZERLAND. This study compared body sway, a measure of postural

stability, between regular brisk walkers and control subjects. Furthermore, the

relationship between body sway and physical activity duration in

postmenopausal women was examined. Subjects were 31 healthy postmenopausal

women, aged 61-71 years. They were recruited from a randomized controlled

study of the influence of brisk walking on bone: 16 women had been completing

20 min d-1 brisk walking, whilst 15 controls had been completing habitual

activities only. Body sway was measured using a swaymeter that measured

displacement at the waist whilst subjects stood on a compliant surface, with eyes

closed, for 1 min. The activity was measured using activity monitors which were

worn at the waist for 3 consecutive days. Body sway (eyes closed, standing on a

compliant surface) was lower in walkers than in controls: 2,958 +/- (SE) 270

versus 5,225+/-371 mm2 min-1, respectively (p < 0.05). A negative correlation

was found between body sway and minutes of physical activity (r = -0.47, p <

0.01). Analysis of variance revealed that body sway differed significantly (p <

0.05) between groups of differing physical activity participation, being 4,839 +/-

499, 4,167 +/- 516, and 2,877 +/- 362 mm2 min-1, respectively, in women

completing <20, 20-40, and >40 min d-1 of physical activity. Body sway was

significantly lower in the most active group than in the least active (p < 0.01).

These data suggest that postural stability is better in regular walkers than in

control subjects. Furthermore, a dose-response relationship was observed

between physical activity and postural stability in postmenopausal women.

These findings provide a preliminary indication that brisk walking, a low-cost and

acceptable form of physical activity for the elderly, could be incorporated into

strategies for improving balance in the elderly.

34. Brown, D. A.; Effgen, S. K.; Palisano, R. J. Performance following ability-focused

physical therapy intervention in individuals with severely limited physical and

cognitive abilities. Phys-Ther. 1998 Sep; 78(9): 934-47; discussion 948-50; ISSN:

0031-9023.

UNITED-STATES. BACKGROUND AND PURPOSE: Do individuals with

severely limited physical and cognitive abilities improve their gross motor abilities

when given physical therapy intervention, and does improvement transfer to

nontreatment settings? SUBJECTS: The subjects were 24 individuals (10 female,

14 male), aged 3 to 30 years (X = 20.1, SD = 8.1), who were nonambulatory and

had limited adaptive behavior. METHODS: Change in gross motor ability during

18 weeks of twice-weekly therapy was measured using goal attainment scaling

(GAS). Three gross motor goals were developed for each subject based on

individual or caregiver needs, with one goal randomly selected as a control.

Physical impairments were treated, and behavioral management principles, low-

level communication approaches, high-repetition practice of goals, and a

progressive reduction of both physical assistance and multisensory cues were

used. An independent rater scored goal level from randomly ordered videotapes

recorded during therapy and in recess and home settings. RESULTS: Mean GAS

T scores were higher for treatment goals (X = 45.6, SD = 10.5) compared with

control goals (X = 34.6, SD = 11.8). When the expected goal level (50) was met

during therapy, mean GAS T scores in recess settings ( X = 35.9, SD = 11.5) and

home settings (X = 42.2, SD = 12.2) were lower. At the conclusion of therapy,

there were no differences in goal levels between treatment and control goals in

both the recess and home settings. CONCLUSION AND DISCUSSION: The

subjects demonstrated improvement of gross motor abilities practiced during

therapy. Level of ability during therapy, however, did not consistently transfer to

the recess of home settings. [Brown DA, Effgen SK, Palisano RJ. Performance

following ability-focused physical therapy intervention in individuals with

severely limited physical and cognitive abilities.

35. Bruder, G.; Kayser, J.; Tenke, C.; Rabinowicz, E.; Friedman, M.; Amador, X.; Sharif,

Z.; Gorman, J. The time course of visuospatial processing deficits in

schizophrenia: an event-related brain potential study. J-Abnorm-Psychol. 1998

Aug; 107(3): 399-411; ISSN: 0021-843X.

UNITED-STATES. Event-related brain potentials (ERPs) were recorded during a

dot enumeration task so as to investigate electrophysiologic correlates of early

visuospatial processing in schizophrenia. Twenty-eight patients having a

diagnosis of schizophrenia (n = 19) or schizoaffective disorder (n = 9) and 28

controls were tested. Patients showed poorer dot enumeration than did controls

and also had markedly reduced early negative ERPs, which began about 150 ms

after stimulus onset at the peak of the N1 potential and reached its maximum

about 275 ms at the N2 peak. The N1 reduction in patients was greatest over left

parietal sites for stimuli in the right visual field. The marked N1 and N2

reductions in patients are supportive of models postulating deficits in early

visuospatial attention and allocation of conceptual resources in schizophrenia.

36. Bussmann, H. B.; Reuvekamp, P. J.; Veltink, P. H.; Martens, W. L.; Stam, H. J.

Validity and reliability of measurements obtained with an "activity monitor" in

people with and without a transtibial amputation. Phys-Ther. 1998 Sep; 78(9):

989-98; ISSN: 0031-9023.

UNITED-STATES. BACKGROUND AND PURPOSE: In this study, the

validity and reliability of measurements obtained with an "Activity Monitor"

(AM) were examined. The instrument is designed to monitor ambulatory activity

by use of accelerometer signals, and it detects several activities associated with

mobility (standing, sitting, lying, transitions, movement-related activities).

SUBJECTS: Four men with a transtibial amputation and 4 men without a

transtibial amputation participated. METHODS: The subjects performed normal

daily activities, during which accelerations were measured and videotape recording

were made (reference method). Validity was assessed by calculating agreement

scores between the AM output and the videotape recordings and by comparing

the number of transitions and the duration of activities determined by both

methods. RESULTS: The overall agreement between the AM output and the

videotape recordings was 90%. Other agreement scores, in addition to the

determination of the number of transitions and the duration of activities, were

generally within a range of error of 0% to 10%. CONCLUSION AND

DISCUSSION: The reliability and validity of the AM measurements appeared to

be good, which supports its potential use in rehabilitation and physical therapy.

[Bussmann HBJ, Reuvekamp PJ, Veltink PH, et al. Validity and reliability of

measurements obtained with an "Activity Monitor" in people with and without a

transtibial amputation.

37. Bussmann, J. B.; Tulen, J. H.; van Herel, E. C.; Stam, H. J. Quantification of physical

activities by means of ambulatory accelerometry: a validation study.

Psychophysiology. 1998 Sep; 35(5): 488-96; ISSN: 0048-5772.

UNITED-STATES. The objective of the study was to assess the validity of an

activity monitor (AM) within a psychophysiological study. The AM was based

on four body-fixed accelerometers and discriminated postures, transitions, and

dynamic activities. Three subjects participated in each of two 4-hr sessions.

During each session, consisting of two protocols, ambulatory accelerometer and

heart rate measurements were made. The output of the AM was compared with

simultaneously recorded video tapes. An overall agreement between AM and

video of 88 and 96% was found. The number of transitions and dynamic periods,

and the duration of activities were well determined. Posture-related heart rate

changes were demonstrated. A three-sensor configuration hardly influenced the

validity scores. The AM appeared to be a valid instrument to quantify aspects of

physical activity, and offers new possibilities for ambulatory

psychophysiological research.. 0; 28981-97-7; 846-49-1.

38. Candau, R.; Belli, A.; Millet, G. Y.; Georges, D.; Barbier, B.; Rouillon, J. D. Energy

cost and running mechanics during a treadmill run to voluntary exhaustion in

humans. Eur-J-Appl-Physiol. 1998 May; 77(6): 479-85; ISSN: 0301-5548.

GERMANY. The aim of the present study was to examine the physiological and

mechanical factors which may be concerned in the increase in energy cost during

running in a fatigued state. A group of 15 trained triathletes ran on a treadmill at

velocities corresponding to their personal records over 3000m [mean 4.53 (SD

0.28) m x s(-1)] until they felt exhausted. The energy cost of running (CR) was

quantified from the net O2 uptake and the elevation of blood lactate

concentration. Gas exchange was measured over 1 min firstly during the 3rd-4th

min and secondly during the last minute of the run. Blood samples were collected

before and after the completion of the run. Mechanical changes of the centre of

mass were quantified using a kinematic arm. A significant mean increase [6.9 (SD

3.5)%, P < 0.001] in CR from a mean of 4.4 (SD 0.4) J x kg(-1) x m(-1) to a mean

of 4.7 (SD 0.4) J x kg(-1) x m(-1) was observed. The increase in the O2 demand of

the respiratory muscles estimated from the increase in ventilation accounted for a

considerable proportion [mean 25.2 (SD 10.4)%] of the increase in CR. A mean

increase [17.0 (SD 26.0)%, P < 0.05] in the mechanical cost (CM) from a mean of

2.36 (SD 0.23) J x kg m(-1) to a mean of 2.74 (SD 0.55) J x kg(-1) x m(-1) was

also noted. A significant correlation was found between CR and CM in the non-

fatigued state (r=0.68, P < 0.01), but not in the fatigued state (r=0.25, NS).

Furthermore, no correlations were found between the changes (from non-fatigued

to fatigued state) in CR and the changes in CM suggesting that the increase in CR

is not solely dependent on the external work done per unit of distance. Since step

frequency decreased slightly in the fatigued state, the internal work would have

tended to decrease slightly which would not be compatible with an increase in CR.

A stepwise regressions showed that the changes in CR were linked (r=0.77, P <

0.01) to the changes in the variability of step frequency and in the variability of

potential cost suggesting that a large proportion of the increase in CR was due to

an increase in the step variability. The underlying mechanisms of the relationship

between CR and step variability remains unclear.. 7782-44-7.

39. Carpenter, M. G.; Bellos, A.; Patla, A. E. Is backward stepping over obstacles

achieved through a simple temporal reversal of forward stepping? Int-J-Neurosci.

1998 Apr; 93(3-4): 189-96; ISSN: 0020-7454.

ENGLAND. The main purpose of the study was to examine whether backward

stepping over obstacles was a simple temporal reversal of kinematic and muscle

activation patterns found in forward obstacle avoidance. Obstacle avoidance was

used as a probe to represent one aspect of walking over variable terrain.

Kinematics, trajectories and muscle activation profiles for forward versus

backward stepping over obstacles revealed that the simple reversal of locomotor

patterns observed for level walking cannot be applied to obstacle avoidance.

However, key kinematic data and limb trajectories for backward leading limb

stepping were found to be similar to existing forward trailing limb data. Therefore,

it appears that stepping over obstacles requires a complex upper level

reorganization of the basic locomotor pattern based on biomechanical and sensory

feedback.

40. Casazza, B. A.; Young, J. L.; Press, J. P.; Heinemann, A. W. Suprascapular nerve

conduction: a comparative analysis in normal subjects. Electromyogr-Clin-

Neurophysiol. 1998 Apr; 38(3): 153-60; ISSN: 0301-150X.

BELGIUM. An electromyographic examination is often utilized to confirm the

diagnosis of suprascapular neuropathy in patients with shoulder pain and

dysfunction. The purpose of this study was to compare three compound motor

action potential (CMAP) recording methods (surface electrode, monopolar needle,

concentric needle) for evaluating suprascapular nerve conduction. Twenty-two

normal, healthy subjects were tested with each method. Differences between the

recording methods were noted for CMAP latencies and amplitudes with the

monopolar needle recordings having the shortest mean latency and greatest mean

amplitude. The monopolar needle recordings also appeared to give a more

reproducible measurement of CMAP latency and evoked amplitude to the

supraspinatus and infraspinatus. Therefore, it may be more accurate to use a

monopolar needle to record suprascapular nerve conduction and determine

abnormalities with a side-to-side latency difference of 0.4 ms being acceptable.

Considering the diverse branching of the suprascapular nerve, and the monopolar

needle's relatively small sampling area of motor fibers, it may be prudent to test

conduction to multiple sites within these muscles for the most accurate

assessment.

41. Cauquil, A. S.; Bessou, M.; Dupui, P.; Bessou, P. Lateral dynamic balance reactions

to circular translation of the visual field. C-R-Acad-Sci-III. 1998 Apr; 321(4):

289-94; ISSN: 0764-4469.

FRANCE. Lateral sway of subjects in spontaneous dynamic balance conditions

on a seesaw platform was measured during a visual stimulation monocularly

produced by a rotating glass covered with a prism membrane. Prism rotation

induced the perception of a circular translation of the whole visual field and an

ocular pursuit movement. Therefore, the retinal slip that occurs in normal pursuit

was cancelled. Strong stereotyped postural reactions were observed in a direction

that depended upon both the vertical visual field deviation and the eye stimulated:

upper position of the right visual field induced a leftward sway resulting from an

extension of the right hemibody; symmetrical reactions occurred for the left

stimulation. The results suggest that the postural reactions recorded depend on

the isolated oculomotor activity and, in addition, on retinal afferences

corresponding to the temporal crescent of the stimulated side, which orientates

the postural reaction on the homolateral lower limb muscles.

42. Censi, L.; Toti, E.; Pastore, G.; Ferro Luzzi, A. The basal metabolic rate and energy

cost of standardised walking of short and tall men. Eur-J-Clin-Nutr. 1998 Jun;

52(6): 441-6; ISSN: 0954-3007.

ENGLAND. OBJECTIVES: To assess the influence of stature on the basal

metabolic rate (BMR) and on the energy cost of standardised walking. A second

objective was assess the accuracy of the FAO/UNU/WHO (1985) equations to

predict BMR. DESIGN/SUBJECTS: Forty-six young men were selected on the

basis of their stature and assigned to the group of short, S (n = 25, mean stature =

1.65 +/- 0.03 m) or of tall, T (n = 21, mean stature = 1.87 +/- 0.04 m). SETTING:

Rome, Italy. INTERVENTIONS: Body composition was assessed by underwater

weighing. BMR and energy cost walking at 5 km/h was measured by the Douglas

bag. RESULTS: Body fat % was similar in the two groups (15.2 +/- 4.3 for S;

17.4 +/- 5.3 for T; ns). The BMR of T was 20% higher than that of S, but 12%

and 10% lower when standardised respectively for body weight (BW) and fat free

mass (FFM). However these differences were removed when BMR was covaried

for BW or FFM, or normalised by BW0.62 or FFM0.64. Measured BMR was

7% for T and 6% for S lower than that predicted by the FAO/WHO/UNU (1985)

equation; the inclusion of stature did not reduce the overestimation. The energy

cost of walking was 27% higher in T than in S, but 9% and 5% lower when

standardised respectively for BW and FFM. The differences disappeared when

expressing the energy cost of walking as net cost per kg FFM. CONCLUSIONS:

Tall people have lower BMR per unit of BW or FFM than short people, and it is

necessary to control for the diverse body mass by the appropriate method.

However, qualitative differences in the composition of FFM are plausible, due to

the diverse proportion of metabolically active internal organs in people of

different height, which might be reflected in the higher BMR/kg FFM of the

shorter subjects. The sex- and age-specific FAO/WHO/UNU (1985) equation

significantly overestimates the BMR of both short and tall people, but there is no

simple explanation of this observation. The energy cost of walking is not affected

by stature when expressed as net cost per kg FFM.

43. Chapillon, P.; Lalonde, R.; Jones, N.; Caston, J. Early development of synchronized

walking on the rotorod in rats. Effects of training and handling. Behav-Brain-Res.

1998 Jun; 93(1-2): 77-81; ISSN: 0166-4328.

NETHERLANDS. There is considerable improvement of motor coordination on

the rotorod during the first 3 weeks of development in rats. The purpose of the

present study was to determine some factors implicated in this improvement.

From days 15-22 of age, rats were: (1) extensively trained on the rotorod; (2)

minimally trained on the rotorod; (3) handled daily but not trained on the rotorod;

and (4) neither handled nor trained. All animals were tested on the rotorod on day

23, with separate groups of the naive rats also being tested on days, 19, 20, 21 or

22. Latencies before falling and the percentage of time spent walking in time to the

movement of the rotating rod were recorded. There was a close correspondence

between these two scores during ontogeny. The percentage of time spent walking

was similar among extensively trained, minimally trained, and handled rats and

significantly higher than that measured in rats tested only on 1 day. These results

indicate that the emergence of this postural sensorimotor skill is more dependent

on the maturation of sensorimotor brain region than on previous training on the

apparatus.

44. Chaturvedi, V.; Gisbergen, J. A. Shared target selection for combined version-vergence

eye movements. J-Neurophysiol. 1998 Aug; 80(2): 849-62; ISSN: 0022-3077.

UNITED-STATES. Primates frequently make rapid binocular eye movements to

reorient gaze in both direction and depth. To explain the unequal movements made

by the two eyes, it often is assumed that they result from the combined action of

a conjugate saccadic system and a vergence contribution. Clearly such a scheme

can only yield coordinated binocular movements if both systems are guided by a

shared or coupled target selection mechanism. To investigate the degree of

cooperation at this level, we studied binocular refixations to target-nontarget

double-stimuli in three-dimensional (3-D) space. Binocular eye movements were

recorded in seven subjects using the scleral coil technique. In the experiments,

20% of trials were composed of a green target and a red nontarget, presented at

the same time, but at different locations in 3-D space. These were alternated

randomly with single-target trials (80%) in which the green stimulus was

presented randomly at one of eight possible positions in 3-D space. Instructions

to the subject emphasized either the speed or accuracy of response. Our findings

show that typical features of the saccadic response to double-stimuli (bistability,

averaging, and a speed-accuracy trade-off), as found in earlier two-dimensional

studies, are also prevalent for initial binocular refixations to double stimuli in 3-D

space. When the first saccadic response is directed to one of the two stimuli, the

vergence system almost invariably makes the same choice. Likewise, when the

saccadic system makes a short-latency averaging response, the vergence system

shows a similar compromise. Statistical analysis shows a high correlation between

saccadic and vergence target selection, strongly suggesting that the amplitude

computation process of both subsystems is due to a common target selection

stage that has access to information about stimulus location in 3-D space.

45. Chaturvedi, V.; Gisbergen, J. A. Shared target selection for combined version-vergence

eye movements. J-Neurophysiol. 1998 Aug; 80(2): 849-62; ISSN: 0022-3077.

UNITED-STATES. Primates frequently make rapid binocular eye movements to

reorient gaze in both direction and depth. To explain the unequal movements made

by the two eyes, it often is assumed that they result from the combined action of

a conjugate saccadic system and a vergence contribution. Clearly such a scheme

can only yield coordinated binocular movements if both systems are guided by a

shared or coupled target selection mechanism. To investigate the degree of

cooperation at this level, we studied binocular refixations to target-nontarget

double-stimuli in three-dimensional (3-D) space. Binocular eye movements were

recorded in seven subjects using the scleral coil technique. In the experiments,

20% of trials were composed of a green target and a red nontarget, presented at

the same time, but at different locations in 3-D space. These were alternated

randomly with single-target trials (80%) in which the green stimulus was

presented randomly at one of eight possible positions in 3-D space. Instructions

to the subject emphasized either the speed or accuracy of response. Our findings

show that typical features of the saccadic response to double-stimuli (bistability,

averaging, and a speed-accuracy trade-off), as found in earlier two-dimensional

studies, are also prevalent for initial binocular refixations to double stimuli in 3-D

space. When the first saccadic response is directed to one of the two stimuli, the

vergence system almost invariably makes the same choice. Likewise, when the

saccadic system makes a short-latency averaging response, the vergence system

shows a similar compromise. Statistical analysis shows a high correlation between

saccadic and vergence target selection, strongly suggesting that the amplitude

computation process of both subsystems is due to a common target selection

stage that has access to information about stimulus location in 3-D space.

46. Chen, R.; Yaseen, Z.; Cohen, L. G.; Hallett, M. Time course of corticospinal

excitability in reaction time and self-paced movements. Ann-Neurol. 1998 Sep;

44(3): 317-25; ISSN: 0364-5134.

UNITED-STATES. We used transcranial magnetic stimulation (TMS) to study

the time course of corticospinal excitability before and after brisk thumb

abduction movements, either in a simple reaction time (RT) paradigm or self-

paced. Premovement increase in corticospinal excitability began about 20 msec

earlier for self-paced compared with simple RT movements. For both simple RT

and self-paced movements after electromyographic (EMG) offset, there was a

first period of increased excitability from 0 to 100 msec, followed by a second

period from 100 to 160 msec. Corticospinal excitability was decreased from about

500 to 1,000 msec after EMG offset for both types of movements. Our results

show that motor preparation that begins 1.5 to 2 seconds before self-paced

movement is not associated with increased corticospinal excitability. The first

phase of increased corticospinal excitability after EMG offset may be due to

activity of motor cortex neuron subthreshold for activating spinal motor neurons,

and the second phase may reflect a subthreshold second agonist burst. The period

of decreased corticospinal excitability after movement corresponds to the onset of

event-related synchronization (ERS) of electroencephalographic signals in the 20-

Hz band, and supports the hypothesis that ERS may be related to an inactive,

idling state of the motor cortex.

47. Cohen, H.; Friedman, E. M.; Lai, D.; Pellicer, M.; Duncan, N.; Sulek, M. Balance in

children with otitis media with effusion. Int-J-Pediatr-Otorhinolaryngol. 1997 Dec

10; 42(2): 107-15; ISSN: 0165-5876.

IRELAND. To determine the presence of balance disorders in young children

who had otitis media with effusion (OME), 25 subjects, aged 13-57 months,

diagnosed by pediatric otolaryngologists, were tested on the gross motor subtest

of the Peabody Developmental Motor Scales, a standardized test of motor

development with established norms. Parents also filled out questionnaires about

their children's balance skills. Subjects with unilateral disease did not differ

significantly from normals. Subjects with bilateral disease, however, were

significantly impaired compared to normals on balance, locomotion and total score

and they were significantly impaired compared to unilateral subjects on all scores.

Parental perceptions of their children's balance correlated poorly with the test

results. These data suggest that young children with bilateral otitis media with

effusion are delayed in developing motor skills that require dynamic balance.

Therefore, in spite of a negative history for balance problems physicians should

consider balance performance when developing a treatment plan. Children with

balance impairments might benefit from more aggressive intervention.

48. Cohen, H.; Friedman, E. M.; Lai, D.; Pellicer, M.; Duncan, N.; Sulek, M. Balance in

children with otitis media with effusion. Int-J-Pediatr-Otorhinolaryngol. 1997 Dec

10; 42(2): 107-15; ISSN: 0165-5876.

IRELAND. To determine the presence of balance disorders in young children

who had otitis media with effusion (OME), 25 subjects, aged 13-57 months,

diagnosed by pediatric otolaryngologists, were tested on the gross motor subtest

of the Peabody Developmental Motor Scales, a standardized test of motor

development with established norms. Parents also filled out questionnaires about

their children's balance skills. Subjects with unilateral disease did not differ

significantly from normals. Subjects with bilateral disease, however, were

significantly impaired compared to normals on balance, locomotion and total score

and they were significantly impaired compared to unilateral subjects on all scores.

Parental perceptions of their children's balance correlated poorly with the test

results. These data suggest that young children with bilateral otitis media with

effusion are delayed in developing motor skills that require dynamic balance.

Therefore, in spite of a negative history for balance problems physicians should

consider balance performance when developing a treatment plan. Children with

balance impairments might benefit from more aggressive intervention.

49. Courage, M. L.; Howe, M. L. The ebb and flow of infant attentional preferences:

evidence for long-term recognition memory in 3-month-olds. J-Exp-Child-

Psychol. 1998 Jul; 70(1): 26-53; ISSN: 0022-0965.

UNITED-STATES. Using paired-comparisons, 3-month-olds' (n = 148)

recognition of dynamic visual events was investigated after retention intervals of 1

minute, 1 day, and 1 and 3 months (Experiment 1) and 1 minute, 1 day, and 1

week (Experiment 2). Participants were either tested at each retention interval

(Multiple Tests) or tested at one interval (Single Test). The proportion of total

looking time to the novel event and the length of the longest look to novel and

familiar events in the first 15 s of the retention test revealed significant novelty

preferences at 1 minute and 1 day and a null preference at 1 week for Multiple-

and Single-Test groups. At 1 month, Multiple- (Proportion of Total Looking

Time and Longest Look) and Single-Test groups (Longest Look only) preferred

the familiar event. The 3-month test revealed a familiarity preference (both

measures) for Single- and a null preference for Multiple-Tests groups. This

changing pattern of attentional preferences is consistent with models of infant

recognition memory in which novelty, familiarity, and null preferences are

considered conjointly and hypothesized to reflect the accessibility of novel and

familiar event representations in memory. Copyright 1998 Academic Press.

50. Crego, F.; Galindo, J.; Quesada, P.; Naches, S.; Pinas, J.; Vila, J.; Pollan, C.; Raguer,

N. [Recurrent peripheral facial paralysis. Our case load from 1995]. Paralisis

facial periferica recidivante. Nuestra casuistica del ano 1995. Acta-

Otorrinolaringol-Esp. 1998 May; 49(4): 280-2; ISSN: 0001-6519.

SPAIN. Of 117 cases of peripheral facial palsy seen in our emergency room in

1995, 10 (8.5%) were relapses. Seven were males and 3, females. Mean age at the

first appearance was 23.6 years. The mean interval between the first facial palsy

and the first recurrence was 10.1 years, and between the first and second

recurrence, 4.6 years. Five of the 10 patients (50%) had a second recurrence. Two

of the 10 patients (20%) had a family history of facial palsy. Only 1 (10%) was

diabetic. Seven of 10 patients achieved a complete functional recovery and 3 had

sequelae. Computed tomography was normal in every patient. In our series, a

family history of facial palsy and low ENoG results were related with a poorer

prognosis. ENoG scan was used as a prognostic and follow-up factor.

51. Cruz Martinez, A.; Munoz, J.; Palacios, F. The muscle inhibitory period by

transcranial magnetic stimulation. Study in stroke patients. Electromyogr-Clin-

Neurophysiol. 1998 Apr; 38(3): 189-92; ISSN: 0301-150X.

BELGIUM. Motor evoked potentials (MEPs) elicited over hand muscles by

transcranial magnetic stimulation (TMS) were studied in healthy individuals and,

bilaterally, in patients with cerebral infarction. Conduction time of the central

motor pathways (CMCT), threshold intensity, and amplitude of the MEPs were

correlated with recovery motor hand function after stroke. Following MEPs by

TMS during tonic muscle contraction, there is a transient suppression of muscle

action. This inhibitory period (IP) was significantly shorter in the upper paretic

limb of stroke patients with spasticity than in normal limb of the patients and

healthy individuals. Shortening of the IP duration was correlated to degree of

upper limb spasticity (Ashworth scale) and may be due to supraspinal level

reduction of the inhibitory function. The IP study contributes to a better

quantification of the hand function in stroke patients.

52. Cruz Martinez, A.; Munoz, J.; Palacios, F. The muscle inhibitory period by

transcranial magnetic stimulation. Study in stroke patients. Electromyogr-Clin-

Neurophysiol. 1998 Apr; 38(3): 189-92; ISSN: 0301-150X.

BELGIUM. Motor evoked potentials (MEPs) elicited over hand muscles by

transcranial magnetic stimulation (TMS) were studied in healthy individuals and,

bilaterally, in patients with cerebral infarction. Conduction time of the central

motor pathways (CMCT), threshold intensity, and amplitude of the MEPs were

correlated with recovery motor hand function after stroke. Following MEPs by

TMS during tonic muscle contraction, there is a transient suppression of muscle

action. This inhibitory period (IP) was significantly shorter in the upper paretic

limb of stroke patients with spasticity than in normal limb of the patients and

healthy individuals. Shortening of the IP duration was correlated to degree of

upper limb spasticity (Ashworth scale) and may be due to supraspinal level

reduction of the inhibitory function. The IP study contributes to a better

quantification of the hand function in stroke patients.

53. Csibra, G.; Tucker, L. A.; Johnson, M. H. Neural correlates of saccade planning in

infants: a high-density ERP study. Int-J-Psychophysiol. 1998 Jul; 29(2): 201-15;

ISSN: 0167-8760.

NETHERLANDS. Neural correlates of saccade planning in 6-month-old infants

were investigated by high-density event-related potentials. Subjects made

saccades to a target stimulus following a time gap from fixation stimulus offset

(gap trials) or with the fixation stimulus still present (overlap trials). Like adults,

infants were slower to make a saccade to the target when the fixation stimulus was

still present. Strikingly, infants did not show clear evidence of the pre-saccadic

components observed in adults which are thought to reflect cortical saccade

planning processes. They did, however, show a left frontal positivity, which we

suggest reflects cortical disinhibition of the colliculus initiated by fixation stimulus

offset, and clear post-saccadic lambda waves. These results indicate that the

frontal cortex already plays a role in action control by 6 months of age, while

other aspects of cortical action planning may not yet be present in certain task

situations.

54. Csibra, G.; Tucker, L. A.; Johnson, M. H. Neural correlates of saccade planning in

infants: a high-density ERP study. Int-J-Psychophysiol. 1998 Jul; 29(2): 201-15;

ISSN: 0167-8760.

NETHERLANDS. Neural correlates of saccade planning in 6-month-old infants

were investigated by high-density event-related potentials. Subjects made

saccades to a target stimulus following a time gap from fixation stimulus offset

(gap trials) or with the fixation stimulus still present (overlap trials). Like adults,

infants were slower to make a saccade to the target when the fixation stimulus was

still present. Strikingly, infants did not show clear evidence of the pre-saccadic

components observed in adults which are thought to reflect cortical saccade

planning processes. They did, however, show a left frontal positivity, which we

suggest reflects cortical disinhibition of the colliculus initiated by fixation stimulus

offset, and clear post-saccadic lambda waves. These results indicate that the

frontal cortex already plays a role in action control by 6 months of age, while

other aspects of cortical action planning may not yet be present in certain task

situations.

55. Davey, N. J.; Rawlinson, S. R.; Maskill, D. W.; Ellaway, P. H. Facilitation of a hand

muscle response to stimulation of the motor cortex preceding a simple reaction

task. Motor-Control. 1998 Jul; 2(3): 241-50; ISSN: 1087-1640.

UNITED-STATES. Transcranial magnetic stimulation (TMS) of the motor

cortex was used to produce compound motor evoked potentials (cMEPs) in the

first dorsal interosseus (FDI) muscle. The size of cMEPs was measured as an

index of corticospinal excitability before and after initiation of a simple reaction

task (SRT). The SRT, consisting of an abduction of the right index finger against a

vertical support in response to a 1 kHz cueing tone, was performed in 6 healthy

male subjects. cMEPs were facilitated when timed to occur just before the fastest

simple reaction time (fSRT). When the cMEP was placed 15.5 +/- 1.5 ms before

the fSRT, its amplitude increased to 176 +/- 36% of the control response seen in

the relaxed state (no SRTs). Facilitation of the cMEP increased to 382 +/- 43% of

the control when it was placed 11.9 +/- 1.5 ms after the fSRT. The facilitation of

cMEP responses prior to the SRT is discussed with particular reference to the

premovement potential that may be recorded over the cortex prior to a voluntary

movement.

56. David, T.; Smye, S.; Dabbs, T.; James, T. A model for the fluid motion of vitreous

humour of the human eye during saccadic movement. Phys-Med-Biol. 1998 Jun;

43(6): 1385-99; ISSN: 0031-9155.

ENGLAND. During saccadic motion the eyewall moves in a manner similar to a

sinusoid or at least can be represented by a sine Fourier series. Motion of the

vitreous is induced by the saccade and the vitreo-retinal interface is subjected to a

time-dependent shear. This force may be a significant factor for retinal tearing in

the neighbourhood of small retinal holes or tears. An analytical viscoelastic model

and a numerical, Newtonian model of the motion of the vitreous are presented and

compared. Under sinusoidal boundary motion the analytical model shows that a

viscous wave propagates inward toward the axis of rotation and the characteristic

length of this wave is a function of the Womersley number. The numerical

solution indicates that the vitreous moves similarly to the analytical result with

small secondary motion; however, this motion allows complete recirculation of

the vitreous over large timescales. Excellent agreement is found between the

analytical and numerical models. The time-dependent fluid shear is evaluated and

from the analytical solution the maximum value of this is found to be proportional

to R0 square root of v(omega)3, where R0 is the eye radius, v the modified

complex viscosity and omega the sinusoidal frequency. This indicates that

myopes have a larger shear force exerted on them by virtue of the larger eye size.

Further work is directed toward a model which links the stress found in the sclera

to that exerted on the vitreo-retinal interface by the vitreous fluid motion.

57. David, T.; Smye, S.; Dabbs, T.; James, T. A model for the fluid motion of vitreous

humour of the human eye during saccadic movement. Phys-Med-Biol. 1998 Jun;

43(6): 1385-99; ISSN: 0031-9155.

ENGLAND. During saccadic motion the eyewall moves in a manner similar to a

sinusoid or at least can be represented by a sine Fourier series. Motion of the

vitreous is induced by the saccade and the vitreo-retinal interface is subjected to a

time-dependent shear. This force may be a significant factor for retinal tearing in

the neighbourhood of small retinal holes or tears. An analytical viscoelastic model

and a numerical, Newtonian model of the motion of the vitreous are presented and

compared. Under sinusoidal boundary motion the analytical model shows that a

viscous wave propagates inward toward the axis of rotation and the characteristic

length of this wave is a function of the Womersley number. The numerical

solution indicates that the vitreous moves similarly to the analytical result with

small secondary motion; however, this motion allows complete recirculation of

the vitreous over large timescales. Excellent agreement is found between the

analytical and numerical models. The time-dependent fluid shear is evaluated and

from the analytical solution the maximum value of this is found to be proportional

to R0 square root of v(omega)3, where R0 is the eye radius, v the modified

complex viscosity and omega the sinusoidal frequency. This indicates that

myopes have a larger shear force exerted on them by virtue of the larger eye size.

Further work is directed toward a model which links the stress found in the sclera

to that exerted on the vitreo-retinal interface by the vitreous fluid motion.

58. Davids, J. R.; Bagley, A. M.; Bryan, M. Kinematic and kinetic analysis of running in

children with cerebral palsy. Dev-Med-Child-Neurol. 1998 Aug; 40(8): 528-35;

ISSN: 0012-1622.

ENGLAND. Computer-based analysis of gait was used to study walking and

running in 19 children with spastic-diplegic cerebral palsy (CP) and 15 healthy

control children. Temporospatial parameters, kinematic and kinetic data were

compared and contrasted between groups for both types of gait. The majority of

children with diplegic CP, who are independent ambulators, are able to run. These

children increase their velocity by increasing their cadence, a mechanism that is

distinct (and presumably less energy efficient) from that used by healthy children.

Sagittal-plane kinematic and kinetic profiles at the ankle in children with CP were

more similar to normal profiles in running than in walking, suggesting that the

primary deviations at the ankle associated with CP are better tolerated at greater

velocities. Relative power analysis showed that, like healthy children, those with

CP depend more upon the proximal musculature about the hip for power

generation as the velocity of gait increases. Children with CP achieve energy

transfer between adjacent joints during walking and running in a manner

comparable to unaffected children. Running is an important activity for children

and should be considered in the functional assessment of those with CP.

59. de Zeeuw, C. I.; van Alphen, A. M.; Koekkoek, S. K.; Buharin, E.; Coesmans, M. P.;

Morpurgo, M. M.; van, den Burg J. Recording eye movements in mice: a new

approach to investigate the molecular basis of cerebellar control of motor learning

and motor timing. Otolaryngol-Head-Neck-Surg. 1998 Sep; 119(3): 193-203;

ISSN: 0194-5998.

UNITED-STATES. The vestibulocerebellum is involved in the control of

compensatory eye movements. To investigate its role in learning and timing of

motor behavior, we investigated compensatory eye movements in mice with the

use of search coils. Wild-type mice showed the ability to increase the gain of their

vestibulo-ocular reflex by visuovestibular training. This adaptation did not occur

in lurcher mice, a natural mouse mutant that completely lacks Purkinje cells.

During the optokinetic reflex the phase of the eye movements of lurcher mice in

reference to the stimulus lagged behind that of wild-type littermates, whereas

during the vestibulo-ocular reflex it led that of the wild-type mice. During

combined optokinetic and vestibular stimulation, the phase of the lurcher mice

lagged behind that of the wild-type mice at the low stimulus frequencies, whereas

it led the phase of the wild-type mice at the high frequencies. In addition, the

optokinetic response of the lurcher mice showed a significantly longer latency

during constant-velocity step stimulation than that of the wild-type mice. We

conclude that Purkinje cells are necessary for both learning and timing of

compensatory eye movements in mice. The present description of gain adaptation

and phase dynamics provides the basis for studies in which the molecular

mechanisms of cerebellar control of compensatory eye movements are

investigated with the use of genetically manipulated mice.

60. Dejardin, S.; Dubois, S.; Bodart, J. M.; Schiltz, C.; Delinte, A.; Michel, C.; Roucoux,

A.; Crommelinck, M. PET study of human voluntary saccadic eye movements in

darkness: effect of task repetition on the activation pattern. Eur-J-Neurosci. 1998

Jul; 10(7): 2328-36; ISSN: 0953-816X.

FRANCE. Using H2(15)O 3D Positron Emission Tomography (PET), regional

cerebral blood flow (rCBF) was measured in six human subjects under two

different conditions: at rest and while performing self-paced horizontal saccadic

eye movements in darkness. These two conditions were repeated four times each.

First, the comparison between the four saccadic and four resting conditions was

investigated in a group and a single subject analysis. Saccades elicited bilateral

rCBF increases in the medial part of the superior frontal gyrus (supplementary

eye field), precentral gyrus (frontal eye field), superior parietal lobule, anterior

medial part of the occipital lobe involving striate and extrastriate cortex (lingual

gyrus and cuneus), and in the right inferior parietal lobule. At the subcortical level,

activations were found in the left putamen. These results mainly replicate

previous PET findings on saccadic control. Second, the interaction between the

experimental conditions and their repetition was examined. When activations

throughout repetition of the same saccadic task are compared, the supplementary

eye fields show a progressive increase of activation. On the contrary, the

activation in the cerebellum, left superior parietal lobule and left occipital cortex

progressively decreases during the scanning session. Given the existence of such

an interaction, the pattern of activations must be interpreted as a function of task

repetition. This may be a factor explaining some apparent mismatch between

different studies.

61. Dejardin, S.; Dubois, S.; Bodart, J. M.; Schiltz, C.; Delinte, A.; Michel, C.; Roucoux,

A.; Crommelinck, M. PET study of human voluntary saccadic eye movements in

darkness: effect of task repetition on the activation pattern. Eur-J-Neurosci. 1998

Jul; 10(7): 2328-36; ISSN: 0953-816X.

FRANCE. Using H2(15)O 3D Positron Emission Tomography (PET), regional

cerebral blood flow (rCBF) was measured in six human subjects under two

different conditions: at rest and while performing self-paced horizontal saccadic

eye movements in darkness. These two conditions were repeated four times each.

First, the comparison between the four saccadic and four resting conditions was

investigated in a group and a single subject analysis. Saccades elicited bilateral

rCBF increases in the medial part of the superior frontal gyrus (supplementary

eye field), precentral gyrus (frontal eye field), superior parietal lobule, anterior

medial part of the occipital lobe involving striate and extrastriate cortex (lingual

gyrus and cuneus), and in the right inferior parietal lobule. At the subcortical level,

activations were found in the left putamen. These results mainly replicate

previous PET findings on saccadic control. Second, the interaction between the

experimental conditions and their repetition was examined. When activations

throughout repetition of the same saccadic task are compared, the supplementary

eye fields show a progressive increase of activation. On the contrary, the

activation in the cerebellum, left superior parietal lobule and left occipital cortex

progressively decreases during the scanning session. Given the existence of such

an interaction, the pattern of activations must be interpreted as a function of task

repetition. This may be a factor explaining some apparent mismatch between

different studies.

62. Delgado Garcia, J. M. Output-to-input approach to neural plasticity in vestibular

pathways. Otolaryngol-Head-Neck-Surg. 1998 Sep; 119(3): 221-30; ISSN: 0194-

5998.

UNITED-STATES. Some thoughts on current interpretations of available data

regarding vestibular compensation at functional, network, and neural levels are

presented. Basic concepts related to neural plasticity (or elasticity) underlying

motor learning and regeneration also are discussed briefly. Modifiability in

vestibular pathways, at both the functional and structural levels, after peripheral

and central axotomy, and subsequent to transient or permanent chemical target

removal, is presented as an experimental ground to explain similarities and

differences between regenerative, compensatory, and adaptive mechanisms in the

mammal central nervous system.. 0.

63. Dell'Osso, L. F.; Williams, R. W.; Jacobs, J. B.; Erchul, D. M. The congenital and see-

saw nystagmus in the prototypical achiasma of canines: comparison to the human

achiasmatic prototype. Vision-Res. 1998 Jun; 38(11): 1629-41; ISSN: 0042-6989.

ENGLAND. We applied new methods for canine eye-movement recording to the

study of achiasmatic mutant Belgian Sheepdogs, documenting their nystagmus

waveforms and comparing them to humans with either congenital nystagmus (CN)

alone or in conjunction with achiasma. A sling apparatus with head restraints and

infrared reflection with either earth- or head-mounted sensors were used. Data

were digitized for later evaluation. The horizontal nystagmus (1-6 Hz) was similar

to that of human CN. Uniocular and disconjugate nystagmus and saccades were

recorded. See-saw nystagmus (SSN), not normally seen with human CN, was

present in all mutants (0.5-6 Hz) and in the one human achiasmat studied thus far.

This pedigree is an animal model of CN and the SSN caused by achiasma or

uniocular decussation. Given the finding of SSN in all mutant dogs and in a human,

achiasma may be sufficient for the development of congenital SSN and, in human

infants, SSN should alert the clinician to the possibility of either achiasma or

uniocular decussation. Finally, the interplay of conjugacy and disconjugacy

suggests independent ocular motor control of each eye with variable yoking in the

dog.