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Papers by Jacques Cremieux

Progress in Brain Research, 1988

This study focuses on how the vestibular system intervenes in the control of locomotion in the ca... more This study focuses on how the vestibular system intervenes in the control of locomotion in the cat, and evaluates the impact of the visual environment on the development and recovery of vestibular functions. Bilateral destruction of the vestibular receptors was therefore combined with selective visual deprivation, both neonatally and in adult animals. The task was specially designed to investigate specific components of goal-directed locomotion, such as dynamic balance, keeping a straight course, and paw guidance during walking, depending on the characteristics of the walking surface. The main criterion of performance was the average walking speed of the animal when subjected to various visual conditions, including stroboscopic illumination. The effects of vestibular deprivation at an early age on locomotion control were found to be no more severe than those of later lesions, which indicates that early developmental processes involving vestibular information do not impinge on nonvestibular functions. As to the vestibular-related functions, they seem to partly develop in conjunction with kinetic visual cues. For instance, navigation in darkness is impaired in strobe-reared subjects. Furthermore, in adult cats, vestibular signals may be used in conjunction with visual reafferent information, since visual paw guidance is impaired in labyrinthectomized cats during walking. However, vestibular control is both necessary and sufficient for dynamic balance, in that it does not depend upon visual experience, and cannot be properly handled by the visual channel in either early or late vestibular-deprived cats. Impairment of this dynamic balance function may partly explain the deficits observed in other components of locomotor control, namely zigzaging or difficulties over irregular ground after labyrinthectomy. The main effect of age in labyrinthectomized cats is visual: in early vestibular-deprived animals, enhanced use is made of positional visual cues to control the direction of locomotion.

Journal of Neurophysiology, 1985

To investigate the dependence of velocity characteristics on spatiotemporal interactions the velo... more To investigate the dependence of velocity characteristics on spatiotemporal interactions the velocity selectivity of 15 geniculate and 72 cortical cells (areas 17 and 18) was examined with light and dark bars before and after masking all but the most sensitive part of the receptive field. The use of a 0.3 degree window proved effective in eliminating enough spatiotemporal interactions to abolish cortical direction selectivity. The same window improved the responsiveness at high velocities in only 26% of the cortical cells preferring low velocities and having a receptive field with nonoverlapping ON and OFF subregions. The remaining 74% showed various degrees of velocity-independent decrease in response amplitude. The only two geniculate cells that had a velocity upper cutoff lost this cutoff when tested with the mask. Cortical units preferring high velocities lost their responsiveness at high velocities in the mask condition, provided that their receptive fields contained nonoverlap...

Journal of Neurophysiology, 1987

The response properties of 196 area 17 cells were studied qualitatively in seven cats reared from... more The response properties of 196 area 17 cells were studied qualitatively in seven cats reared from birth in a stroboscopically illuminated environment (frequency, 2/s; duration, 200 microseconds). Quantitative testing with the multihistogram technique was carried out in 115 cells. As control population, 453 neurons recorded in area 17 of the normal adult cat and tested qualitatively (of which 301 neurons were tested quantitatively) were available. In area 17 of strobe-reared cats, a number of spatial characteristics of receptive fields investigated with hand-held stimuli were found to be abnormal. There was a strong reduction in the encounter frequency both of end-stopped cells and of binocularly driven cells in the strobe-reared cats. Central receptive fields in strobe-reared cats were wider than in normal cats, but the increase in receptive-field width with eccentricity was still observed. More cells than in normal cats showed either no selectivity or only a weak bias for stimulus ...

Annales De Kinesitherapie, 1995

Cet article tente de faire une synthese sur l'evolution des differents aspects sensoriels et ... more Cet article tente de faire une synthese sur l'evolution des differents aspects sensoriels et moteurs associes aux effets de l'entrainement sportif sur le controle postural. Nous proposons, au regard de la litterature et de resultats experimentaux, une discussion sur la variable sensori-motrice controlee par le Systeme Nerveux Central dans le maintien postural en fonction d'un mouvement propose, du choix des afferences sensorielles de surveillance en fonction de la pratique sportive et du principe d'economie qui sous-tend cette selection, et enfin de l'affinement ou de la construction de strategies motrices liees a la pratique sportive et ceci en fonction de la tâche proposee.

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Agressologie: revue internationale de physio-biologie et de pharmacologie appliquées aux effets de l'agression, 1976

L'objectif de cette recherche etait d'examiner si les facteurs impliques dans la variabil... more L'objectif de cette recherche etait d'examiner si les facteurs impliques dans la variabilite de la contribution sensorielle au controle postural (orientation et stabilisation) etaient plus relies a la typologie perceptive des sujets (dependance-independance au champ) ou a la typologie des sujets concernant la pratique sportive. L'hypothese etait que les typologies perceptives pourraient expliquer la variabilite du controle postural et correspondre a des typologies sensori-motrices equivalentes. Dans une experience de controle postural, 18 sujets masculins etaient selectionnes a priori sur la base de leur score au test du cadre et de la baguette (RFT). Ces sujets ont ete ensuite testes au test du disque et de la baguette (RDT), en vue d'etablir leur dependance relative aux signaux visuels dynamiques. Ils ont ete alors regroupes selon trois approches differentielles. Dans les deux premieres, ils etaient regroupes selon leur dependance perceptive aux indices visuels statiques ou dynamiques. Dans une derniere approche differentielle, les sujets etaient regroupes en fonction de leur experience sportive (experts vs novices). Dans l'epreuve posturale, les sujets devaient se tenir dans la position Romberg sensibilisee devant un cadre oriente verticalement ou inclinee a 18°, et eclaire en lumiere normale ou stroboscopique (3 eclairs/s). L'obscurite constituait la condition controle. L'orientation et la stabilite laterale du corps et de la tete etaient enregistres au moyen d'un systeme ELITE. Le resultat principal est que les sujets dependants ont des strategies differentes des sujets independants dans le controle de l'orientation et de la stabilisation. Les sujets dependants etaient plus sensibles au cadre incline et etaient beaucoup moins stables que les sujets independants. Les sujets dependants emploient des indices essentiellement visuels, non seulement pour estimer leur verticale subjective, mais encore pour controler la stabilite et l'orientation du corps. Les performances posturales sont correlees avec la dependance aux indices visuels statiques et dynamiques. Ces resultats montrent l'existence d'interactions, entre les styles perceptifs et la contribution visuelle au controle postural, qui contribuent a la variabilite inter-sujets dans les habiletes d'equilibre postural.

Perceptual and Motor Skills, 1994

Decreasing the visual sampling rate by reducing the stroboscopic frequency affected the postural ... more Decreasing the visual sampling rate by reducing the stroboscopic frequency affected the postural performance of human subjects. At low strobe frequencies of up to 2 flashes/sec., at which only static visual cues were available, no decrease in subjects' mean postural sway was previously observed as compared to their equilibrium behavior without vision. In this experiment, to test the hypothesis that there may be a differential sensitivity to static visual cues in the control of postural equilibrium, we examined the possible effects of subjects' sex and previous sports training on this sensitivity. The static postural equilibrium abilities of 70 subjects of both sexes were tested in a sharpened Romberg position. Performance was measured with accelerometers within a vertical cylinder under normal illumination, 2-Hz stroboscopic light, and darkness. Comparisons between the average postural performances under 2-Hz strobe light and darkness showed no significant differences betwee...

Neuroscience Letters, 1999

Neuroscience Letters, 1979

Journal of Biomechanics, 1994

Human Movement Science, 1998

The present study addresses the question of the links between visual perceptual dependenceindepe... more The present study addresses the question of the links between visual perceptual dependenceindependence and the visual contribution to postural control. In our differential approach, the effects of both static and dynamic visual cues on body posture (orientation ...