Papers by CREMIEUX Jacques
Science & Sports, 2004
Introduction. -L'apnée réalisée en milieu aérien comme aquatique induit des adaptations physiolog... more Introduction. -L'apnée réalisée en milieu aérien comme aquatique induit des adaptations physiologiques ayant pour objectif de maintenir la perfusion des organes « nobles » (cerveau, coeur). Lors de sa réalisation en immersion, la gestion du temps est primordiale afin d'accomplir une performance sans se mettre en situation de danger. Ainsi, on peut se demander dans quelles mesures l'apnée statique peut perturber l'estimation du temps ?
Behavioral Neuroscience, 1992
The aim of this study was to design an animal model of sensory substitution in the case of blindn... more The aim of this study was to design an animal model of sensory substitution in the case of blindness. Six kittens were binocularly enucleated; as adults, they were fitted with an ultrasonic echolocation prosthesis. This device provided the animals with auditory signals that coded distance and direction of obstacles. Animals were trained by operant conditioning to use the prosthesis in various behavioral situation. The results showed that visually deprived animals tried to solve the task using natural information and that they only used artificial information provided by the prosthesis when they were unable to succeed with natural cues. Under these conditions, it was asserted that in a jumping test these animals evaluated depth by means of the prosthesis; in a locomotion task in a maze, it was also demonstrated that they could use the prosthesis for avoiding obstacles.
Experimental Brain Research, 1997
The present paper addresses the question of the possible links between perceptive visual field d... more The present paper addresses the question of the possible links between perceptive visual field dependence-independence and the visual contribution to postural control. In our differential approach, visual field dependent (FD) and independent (FI) subjects were selected on the basis of their score in the Rod and Frame Test (subjective vertical). The hypothesis that we have tested is that the FD subjects use mainly visual cues for estimating not only their subjective vertical but also their body orientation and stability. Moreover, we have postulated that these subjects use mainly dynamic visual cues to control their postural stability. In the postural test, the selected subjects were instructed to stand in the sharpened Romberg position in darkness and under normal or stroboscopic illumination, in front of either a vertical or a tilted frame. Lateral head and body orientation and stability were measured. We found that: (1) all subjects leaned slightly towards the tilted frame (postural frame effect), and this was obtained on the basis of the static visual cues alone; (2) FD subjects were less stable than FI subjects, and their stability required the use of dynamic visual cues, mainly extracted from the vertical frame. In FI subjects, static visual cues may act as a complementary regulation, enhancing stability even with a strobe tilted frame. We thus demonstrate that visual field dependence interacts with the visual contribution to postural control.
Experimental Brain Research, 1984
Classical experiments on the ability of cats to turn in the air during a free fall, the air right... more Classical experiments on the ability of cats to turn in the air during a free fall, the air righting reflex, have shown that vestibular and visual cues can play a role in this behavior. The development of this air righting reflex in kittens blinded since birth has been studied. The results show that the development in the blinded kittens is the same as in normal kittens with vision: mature by 33 days. This result and the comparison with other studies confirm that the air righting reflex is primarily a vestibular controlled reaction.
Journal of Biomechanics, 1994
Neuroscience Letters, 2004
Body sway was studied in standing with eyes closed during quiet breathing and apnoea. The hypothe... more Body sway was studied in standing with eyes closed during quiet breathing and apnoea. The hypothesis was that absence of ventilation improved balance. Performance and control of balance were assessed by centre of gravity and centre of pressure motions respectively. Eight healthy male subjects participated in the study. The analysis was performed for the first 20s when no activity of the diaphragm and no force variation at thoracic and abdominal levels were observed in apnoea condition. Performance and control were significantly improved in apnoea from 17 to 26% for the planar parameters; this improvement was only observed along the medio-lateral axis (around 34%), probably due to upper body asymmetry and diminution of the number of degrees of freedom that can be mobilised along this axis. In conclusion, ventilation in quiet breathing is a perturbing factor in human standing.
Neuroscience, 2010
The causes of the interindividual differences (IDs) in how we perceive and control spatial orient... more The causes of the interindividual differences (IDs) in how we perceive and control spatial orientation are poorly understood. Here, we propose that IDs partly reflect preferred modes of spatial referencing and that these preferences or "styles" are maintained from the level of spatial perception to that of motor control. Two groups of experimental subjects, one with high visual field dependency (FD) and one with marked visual field independency (FI) were identified by the Rod and Frame Test, which identifies relative dependency on a visual frame of reference (VFoR). FD and FI subjects were tasked with standing still in conditions of increasing postural difficulty while visual cues of self-orientation (a visual frame tilted in roll) and self-motion (in stroboscopic illumination) were varied and in darkness to assess visual dependency. Postural stability, overall body orientation and modes of segmental stabilization relative to either external (space) or egocentric (adjacent segments) frames of reference in the roll plane were analysed. We hypothesized that a moderate challenge to balance should enhance subjects' reliance on VFoR, particularly in FD subjects, whereas a substantial challenge should constrain subjects to use a somatic-vestibular based FoR to prevent falling in which case IDs would vanish. The results showed that with increasing difficulty, FD subjects became more unstable and more disoriented shown by larger effects of the tilted visual frame on posture. Furthermore, their preference to coalign body/VFoR coordinate systems lead to greater fixation of the head-trunk articulation and stabilization of the hip in space, whereas the head and trunk remained more stabilized in space with the hip fixed on the leg in FI subjects. These results show that FD subjects have difficulties at identifying and/or adopting a more appropriate FoR based on proprioceptive and vestibular cues to regulate the coalignment of posturo/exocentric FoRs. The FI subjects' resistance in the face of altered VFoR and balance challenge resides in their greater ability to coordinate movement by coaligning body axes with more appropriate FoRs (provided by proprioceptive and vestibular co-variance). (B. Isableu). Abbreviations: AI, anchoring index; FD, field dependency; FI, field independency; FOR, frame of reference; HSTS, head stabilization on the trunk strategy; IDs, interindividual differences; MR, monopodal Romberg; NR, normal Romberg; RFT, rod and frame test; SR, sharpened Romberg; TC, tilted frame continuous vision; TS, tilted frame strobe vision; VC, vertical frame continuous vision; VFOR, visual frame of reference; VS, vertical frame strobe vision.
Neuroscience Letters, 2004
The purpose of this study was to investigate the transfer of postural ability by comparing the le... more The purpose of this study was to investigate the transfer of postural ability by comparing the level of performance and postural control of elite gymnasts in postures specifically trained or not. Fifteen elite gymnasts were asked to stand as still as possible with eyes opened in three conditions: bipedal, unipedal and handstand. Surface and mean velocity of the centre of pressure motions were used to quantify respectively performance and postural control. A ranking was made for each parameter to determine the level of each subject. As a whole, the subject's level of postural performance and control in one condition was not correlated to the corresponded level in another condition. Therefore, postural ability of elite gymnasts in the handstand is not transferable to upright standing postures. q
Archives of Physiology and Biochemistry, 1984
ABSTRACT
Archives of Physiology and Biochemistry, 1984
... The apparatus was a modification of the ma-zes designed by FISH & ROBINSON (1971), andCRA... more ... The apparatus was a modification of the ma-zes designed by FISH & ROBINSON (1971), andCRABTREE & RIESEN (1979). The cats ... References CRABTREE, JW & RIESEN, A. H. (1979) Dev. Psychobiol. 12, 291-303. FISH, S. E. & ROBINSON, J. S. (1971) Psychon. Sci. ...
Neuroscience Letters, 1999
We studied the degree of dependence on vision, for postural control and for perception, among mal... more We studied the degree of dependence on vision, for postural control and for perception, among male adult dancers and untrained subjects. First, body sways were analyzed on a free seesaw platform. Fast Fourier transform processing allowed spectral frequency analysis of the platform sways recorded by an accelerometer. Secondly, a visual dependence test, the rod and frame test (RFT) was used. Professional dancers were signi®cantly more stable and less dependent on vision for postural control and for perception than untrained subjects. Presumably, professional dance training strengthens the accuracy of proprioceptive inputs and shifts sensorimotor dominance from vision to proprioception. For the dancers, there was interaction between the RFT visual dependence and the visual control of posture: the less visualdependent they were for the RFT, the more stable they were in dynamic balance conditions. q
Experimental Brain Research, 1985
The differential contributions of static versus dynamic visual cues to postural control were stud... more The differential contributions of static versus dynamic visual cues to postural control were studied in human subjects. Lateral body oscillations were measured with accelerometers located at head, hips and ankle levels, while subjects righted their balance under various mechanical conditions: i) on either a soft (foam rubber) support or a hard one, and ii) in either the classical or the sharpened Romberg stance. The visual pattern (horizontal or vertical rectangular grating) was illuminated with either a stroboscopic bulb or a normal one, and control measurements were also taken in darkness for each mechanical condition. Acceleration signals were processed into their frequency power spectra, the mean area and shape of which were taken to characterize the postural skills involved and the effects of either the visual suppressions or the mechanical destabilizations. Although dynamic visual cues have already been found to play a major role in the control of lateral body sway (Amblard and Crémieux 1976), we demonstrate here that static visual cues, the only ones available under stroboscopic illumination, also make a clear though minor contribution. Hence we suggest the existence of two modes of visual control of lateral balance in man, which are well separated in terms of the frequency range of body sway: the first mechanism, which operates below 2 Hz and is strobe-resistant, seems to control the orientation of the upper part of the body; the second mechanism, which operates above 4 Hz, centers on about 7 Hz and is strobe-vulnerable, seems to immobilize the body working upwards from the feet. Thus static visual cues may slowly control re-orientation or displacement, whereas dynamic visual cues may contribute to fast stabilization of the body. In between the frequency ranges at which these two visuomotor mechanisms come into play, at about 3 Hz, there is what we call a “blind frequency”, a visually neutral sway frequency which may arise from the incompatibility of visual reorientation with visual stabilization, and where vision appears unable to reduce postural sway to any marked extent. Transmission of the destabilization produced by suppression of visual cues or by mechanical methods from one anatomical level to another is also briefly discussed in terms of bio-mechanical constraints, and the correlations between various pairs of levels are considered.
Experimental Brain Research, 2006
Static roll head tilt induces bias in the trajectory of upper limb voluntary movements. The aim o... more Static roll head tilt induces bias in the trajectory of upper limb voluntary movements. The aim of the experiment was to investigate whether this bias is dependant on the perception of body configuration rather than on its actual configuration. We used the ‘return’ phenomenon as a method to produce dissociation between perceived and actual head tilt. Static roll head tilt in supine subjects was sustained for 15 min during which subjects were periodically required to estimate verbally the tilt of their head respective to their trunk and draw, with their right index finger, straight lines aligned with their trunk. After 15 min, subjects’ head were realigned with the trunk, and subjects continued to give verbal estimate of head position and perform the motor task. Results showed that the initial angular deviation of the lines in the direction opposite to head tilt gradually diminished. The adaptation was noticeable within the first 3–5 min of tilt and subsequently diminished. Verbal estimates confirmed the return phenomenon, i.e. subjects perceived their head as slowly returning towards its neutral position after a few minutes of sustained tilt. When realigned with the trunk, subjects experienced the illusion that their head was tilted in the opposite direction to the initial head tilt and a line deviation in the opposite direction to those made on initial exposure was observed (after-effect). These results indicate that the angular deviation in motor production observed in condition of static head tilt were largely related to the perceived body configuration and therefore favour the hypothesis that the conscious perception of body configuration plays a key role in organising sensorimotor tasks.
Archives of Physiology and Biochemistry, 1984
ABSTRACT Receptive field (RF) width was measured as a function of retinal eccentricity in areas 1... more ABSTRACT Receptive field (RF) width was measured as a function of retinal eccentricity in areas 17 and 18 of normal and strobe-reared animals. In the normal animal RF width increases with eccentricity both in areas 17 and 18 but more steeply in area 18 than in area 17. The latter fact is in keeping with the smaller dimension of area 18 compared to area 17 (see Orban, 1984, for review). In normal animals there is an inverse relationship between receptive field (RF) width and cortical magnification (Hubel & Wiesel, 1974; Albus, 1975; Dow et al., 1981).
International Journal of Sports Medicine, 2005
Vision Research, 1984
We have compared responses of cat visual cortical cells of area 17 to continuously illuminated mo... more We have compared responses of cat visual cortical cells of area 17 to continuously illuminated moving slits and to moving slits illuminated stroboscopically at different rates (70-Z Hz) using quantitative multihistogram techniques. At strobe rates over 30 Hz response characteristics of cortical cells are almost identical under both conditions. except for a lower response level under stroboscopic illumination. As strobe rates decrease below 30 Hz. direction selectivity and velocity tuning are severely impaired and some crfls start responding to the individual strobe flashes rather than to the motion of the slit.
International Journal of Sports Medicine, 2005
The physiological effects of increasing exercise duration at moderate intensity are well known. W... more The physiological effects of increasing exercise duration at moderate intensity are well known. When exercise lasts more than 2 h, a decrease in muscular performance is commonly reported even in well-trained subjects (e.g. ). The mechanisms underlying these reductions in performance are related to either peripheral (alteration in muscular function) or central (impairment in central nervous system drive) fatigue phenomena (for review, see ). Little is known about any possible detrimental effects of prolonged exercise on mood or cognitive performance. Whether deterioration in cognitive performance occurs when exercise is prolonged exercise is not clear .
Vision Research, 1989
Spectacle refraction of eyes of strobe.-reared animals was compared to that of normal cats. Strob... more Spectacle refraction of eyes of strobe.-reared animals was compared to that of normal cats. Strobe reared cats were found to be significantly more myopic than normal cats.
Uploads
Papers by CREMIEUX Jacques