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International audience; Both the gap and overlap paradigm may reveal the interaction between fixating and moving the eyes, but the effects of the overlap paradigm have not been fully characterized yet. Here we present a series of experiments probing how an overlap paradigm, combined with the manipulation of stimuli durations, saliency and transient changes might modulate saccadic reaction time distributions. We recorded saccadic reaction time in four participants in six experiments in which a saccade-target appeared at a pseudo-random amplitude after a fixation period. First, we parametrically manipulated the duration of the overlap using a range of intervals (from 0 to 200 ms). In a second experiment we probed the interaction of various foreperiod intervals (i.e. the duration of the fixation period prior to saccade-target onset) and overlap using two overlap intervals (20 or 140 ms). In two additional experiments we manipulated either the stimuli sizes or their contrast ratio in overlap paradigms (20 or 140 ms). Lastly, we introduced a visual transient during the overlap interval via two manipulations (both with a range of SOA): either a distractor ring appeared around the fixation-target, or a dynamic random noise patch replaced the fixation-target. Results show reliable modifications in the latency distributions depending on the overlap interval as well as idiosyncratic differences. Additional experimental manipulations also affected the latency distributions revealing strong interacting inhibitory processes. We conclude that the effects of overlap intervals may combine with the influence of other stimuli properties affecting decision process.

The objects located straight-ahead of the body are preferentially processed by the visual system. They are more rapidly detected and evoke stronger BOLD responses in early visual areas than elements that are retinotopically identical but located at eccentric spatial positions. To characterize the dynamics of the underlying neural mechanisms, we recorded in 29 subjects the EEG responses to peripheral targets differing solely by their locations with respect to the body. Straight-ahead stimuli led to stronger responses than eccentric stimuli for several components whose latencies ranged between 70 and 350 ms after stimulus onset. The earliest effects were found at 70 ms for a component that originates from occipital areas, the contralateral P1. To determine whether the straight-ahead direction affects primary visual cortex responses, we performed an additional experiment (n = 29) specifically designed to generate two robust components, the C1 and C2, whose cortical origins are constrained within areas V1, V2 and V3. Our analyses confirmed all the results of the first experiment and also revealed that the C2 amplitude between 130 and 160 ms after stimulus onset was significantly stronger for straight-ahead stimuli. A frequency analysis of the pre-stimulus baseline revealed that gaze-driven alterations in the visual hemi-field containing the straight-ahead direction were associated with a decrease in alpha power in the contralateral hemisphere, suggesting the implication of specific neural modulations before stimulus onset. Altogether, our EEG data demonstrate that preferential responses to the straight-ahead direction can be detected in the visual cortex as early as about 70 ms after stimulus onset. Electronic supplementary material The online version of this article (10.1007/s00429-019-01988-5) contains supplementary material, which is available to authorized users.

International audience; In larval xenopus, locomotor-induced oculomotor behavior produces gaze-stabilizing eye movements to counteract the disruptive effects of tail undulation during swimming. While neuronal circuitries responsible for feed-forward intrinsic spino-extraocular signaling have recently been described, the resulting oculomotor behavior remains poorly understood. Conveying locomotor CPG efference copy, the spino-extraocular motor command coordinates the multi-segmental rostrocaudal spinal rhythmic activity with the extraocular motor activity. By recording sequences of xenopus tadpole free swimming, we quantified the temporal calibration of conjugate eye movements originating from spino-extraocular motor coupled activity during pre-metamorphic tail-based undulatory swimming. Our results show that eye movements are produced only during robust propulsive forward swimming activity and increase with the amplitude of tail movements. The use of larval isolated in vitro and semi-intact fixed head preparations revealed that spinal locomotor networks driving the rostral portion of the tail set the precise timing of the spino-extraocular motor coupling by adjusting the phase relationship between spinal segment and extraocular rhythmic activity with the swimming frequency. The resulting spinal-evoked oculomotor behavior produced conjugated eye movements that were in phase opposition with the mid-caudal part of the tail. This time adjustment is independent of locomotor activity in the more caudal spinal parts of the tail. Altogether our findings demonstrate that locomotor feed-forward spino-extraocular signaling produce conjugate eye movements that compensate specifically the undulation of the mid-caudal tail during active swimming. Finally, this study constitutes the first extensive behavioral quantification of spino-extraocular motor coupling, which sets the basis for understanding the mechanisms of locomotor-induced oculomotor behavior in larval frog.

International audience; Several studies in adults having observed the effect of eye movements on postural control provided contradictory results. In the present study, we explored the effect of various oculomotor tasks on postural control and the effect of different postural tasks on eye movements in eleven children (7.8 ± 0.5 years) and nine adults (30.4 ± 6.3 years). To vary the difficulty of the oculomotor task, three conditions were tested: fixation, prosaccades (reactive saccades made toward the target) and antisaccades (voluntary saccades made in the direction opposite to the visual target). To vary the difficulty of postural control, two postural tasks were tested: Standard Romberg (SR) and Tandem Romberg (TR). Postural difficulty did not affect oculomotor behavior, except by lengthening adults' latencies in the prosaccade task. For both groups, postural control was altered in the antisaccade task as compared to fixation and prosaccade tasks. Moreover, a ceiling effect was found in the more complex postural task. This study highlighted a cortical interference between oculomotor and postural control systems.

Saccadic intrusions (SIs), predominantly horizontal saccades that interrupt accurate fixation, include square-wave jerks (SWJs; the most common type of SI), which consist of an initial saccade away from the fixation target followed, after a short delay, by a return saccade that brings the eye back onto target. SWJs are present in most human subjects, but are prominent by their increased frequency and size in certain parkinsonian disorders and in recessive, hereditary spinocerebellar ataxias. SWJs have been also documented in monkeys with tectal and cerebellar etiologies, but no studies to date have investigated the occurrence of SWJs in healthy nonhuman primates. Here we set out to determine the characteristics of SWJs in healthy rhesus macaques (Macaca mulatta) during attempted fixation of a small visual target. Our results indicate that SWJs are common in healthy nonhuman primates. We moreover found primate SWJs to share many characteristics with human SWJs, including the relationship between the size of a saccade and its likelihood to be part of a SWJ. One main discrepancy between monkey and human SWJs was that monkey SWJs tended to be more vertical than horizontal, whereas human SWJs have a strong horizontal preference. Yet, our combined data indicate that primate and human SWJs play a similar role in fixation correction, suggesting that they share a comparable coupling mechanism at the oculomotor generation level. These findings constrain the potential brain areas and mechanisms underlying the generation of fixational saccades in human and nonhuman primates., This study was supported by Barrow Neurological Foundation (http://www.thebarrow.org/) to SLM and SMC. National Science Foundations (Awards 0852636 and 1153786 to SMC and Award 0726113 to SLM).

We used the [14C]-2-deoxyglucose method to study the location and extent of primate frontal lobe areas activated for saccades and fixation and the retrograde transneuronal transfer of rabies virus to determine whether these regions are oligosynaptically connected with extraocular motoneurons. Fixation-related increases of local cerebral glucose utilization (LCGU) values were found around the fundus of the inferior limb of the arcuate sulcus (AS) just ventral to its genu, in the dorsomedial frontal cortex (DMFC), cingulate cortex, and orbitofrontal cortex. Significant increases of LCGU values were found in and around both banks of the AS, DMFC, and caudal principal, cingulate, and orbitofrontal cortices of monkeys executing visually guided saccades. All of these areas are oligosynaptically connected to extraocular motoneurons, as shown by the presence of retrogradely transneuronally labeled cells after injection of rabies virus in the lateral rectus muscle. Our data demonstrate that the arcuate oculomotor cortex occupies a region considerably larger than the classic, electrical stimulation-defined, frontal eye field. Besides a large part of the anterior bank of the AS, it includes the caudal prearcuate convexity and part of the premotor cortex in the posterior bank of the AS. They also demonstrate that the oculomotor DMFC occupies a small area straddling the ridge of the brain medial to the superior ramus of the AS. Our results support the notion that a network of several interconnected frontal lobe regions is activated during rapid, visually guided eye movements and that their output is conveyed in parallel to subcortical structures projecting to extraocular motoneurons.

Summary Background Self-generated body movements require compensatory eye and head adjustments in order to avoid perturbation of visual information processing. Retinal image stabilization is traditionally ascribed to the transformation of visuovestibular signals into appropriate extraocular motor commands for compensatory ocular movements. During locomotion, however, intrinsic "efference copies" of the motor commands deriving from spinal central pattern generator (CPG) activity potentially offer a reliable and rapid mechanism for image stabilization, in addition to the slower contribution of movement-encoding sensory inputs. Results Using a variety of in vitro and in vivo preparations of Xenopus tadpoles, we demonstrate that spinal locomotor CPG-derived efference copies do indeed produce effective conjugate eye movements that counteract oppositely directed horizontal head displacements during undulatory tail-based locomotion. The efference copy transmission, by which the extraocular motor system becomes functionally appropriated to the spinal cord, is mediated by direct ascending pathways. Although the impact of the CPG feedforward commands matches the spatiotemporal specificity of classical vestibulo-ocular responses, the two fundamentally different signals do not contribute collectively to image stabilization during swimming. Instead, when the CPG is active, horizontal vestibulo-ocular reflexes resulting from head movements are selectively suppressed. Conclusions These results therefore challenge our traditional understanding of how animals offset the disruptive effects of propulsive body movements on visual processing. Specifically, our finding that predictive efference copies of intrinsic, rhythmic neural signals produced by the locomotory CPG supersede, rather than supplement, reactive vestibulo-ocular reflexes in order to drive image-stabilizing eye adjustments during larval frog swimming, represents a hitherto unreported mechanism for vertebrate ocular motor control.

International audience; We are usually unaware of the brief but large illumination changes caused by blinks, presumably because of blink suppression mechanisms. In fMRI however, increase of the BOLD signal was reported in the visual cortex, e.g. during blocks of voluntary blinks (Bristow, Frith and Rees, 2005) or after spontaneous blinks recorded during the prolonged fixation of a static stimulus (Tse, Baumgartner and Greenlee, 2010). We tested whether such activation, possibly related to illumination changes, was also present during standard fMRI retinotopic and visual experiments and was large enough to contaminate the BOLD signal we are interested in. We monitored in a 3T scanner the eyeblinks of 14 subjects who observed three different types of visual stimuli, including periodic rotating wedges and contracting/expanding rings, event-related Mondrians and graphemes, while fixating. We performed event-related analyses on the set of detected spontaneous blinks. We observed large and widespread BOLD responses related to blinks in the visual cortex of every subject and whatever the visual stimulus. The magnitude of the modulation was comparable to visual stimulation. However, blink-related activations lay mostly in the anterior parts of retinotopic visual areas, coding the periphery of the visual field well beyond the extent of our stimuli. Blinks therefore represent an important source of BOLD variations in the visual cortex and a troublesome source of noise since any correlation, even weak, between the distribution of blinks and a tested protocol could trigger artifactual activities. However, the typical signature of blinks along the anterior calcarine and the parieto-occipital sulcus allows identifying, even in the absence of eyetracking, fMRI protocols possibly contaminated by a heterogeneous distribution of blinks.

International audience; The present study investigates the human-specificity of the orienting system that allows neonates to look preferentially at faces. Three experiments were carried out to determine whether the face-perception system that is present at birth is broad enough to include both human and nonhuman primate faces. The results demonstrate that the newborns did not show any spontaneous visual preference for the human face when presented simultaneously with a monkey face that shared the same features, configuration, and low-level perceptual properties (Experiment 1). The newborns were, however, able to discriminate between the 2 faces belonging to the 2 different species (Experiment 2). In Experiment 3, the newborns were found to prefer looking at an upright, compared with an inverted, monkey face, as they do for human faces. Overall, the results demonstrate that newborns perceive monkey and human faces in a similar way. These findings are consistent with the hypothesis that the system underlying face preference at birth is broad enough to bias newborns' attention toward both human and nonhuman primate faces.

International audience; The eyes do not stay perfectly still during attempted fixation; fixational eye movements and saccadic intrusions (SIs) continuously change the position of gaze. The most common type of SI, square-wave jerks (SWJs), consists of saccade pairs that appear purely horizontal on clinical inspection: the first saccade moves the eye away from the fixation target, and after a short interval, the second saccade brings it back toward the target. SWJs are prevalent in certain neurological disorders, including progressive supranuclear palsy (PSP). Here, we developed an objective method to identify SWJs. We found that SWJs are more frequent, larger, and more markedly horizontal in PSP patients than in healthy human subjects. Furthermore, the loss of a vertical component in fixational saccades and SWJs was the eye movement feature that best distinguished PSP patients from controls. We moreover determined that, in PSP patients and controls, the larger the saccade the more likely it was part of a SWJ. Furthermore, saccades produced by PSP patients had equivalent properties whether they were part of a SWJ or not, suggesting that normal fixational saccades (microsaccades) are rare in PSP. We propose that fixational saccades and SIs are generated by the same neural circuit and that, both in PSP patients and in controls, SWJs result from a coupling mechanism that generates a second corrective saccade shortly after a large fixation saccade. Because of brainstem and/or cerebellum impairment, fixational saccades in PSP are abnormally large and thus more likely to trigger a corrective saccade, giving rise to SWJs.

International audience; Three- to 4-month-old infants reared by female caregivers display a spontaneous preference for individual adult women's over men's faces. Here we report that this preference extends to prototype girl over boy faces. The findings suggest transfer of gender-diagnostic facial information from individual adult to prototype child faces.

International audience; Gaze aversion could be a central component of the physiopathology of social phobia. The emotions of the people interacting with a person with social phobia seem to model this gaze aversion. Our research consists of testing gaze aversion in subjects with social phobia compared to control subjects in different emotional faces of men and women using an eye tracker. Twenty-six subjects with DSM-IV social phobia were recruited. Twenty-four healthy subjects aged and sex-matched constituted the control group. We looked at the number of fixations and the dwell time in the eyes area on the pictures. The main findings of this research are: confirming a significantly lower amount of fixations and dwell time in patients with social phobia as a general mean and for the 6 basic emotions independently from gender; observing a significant correlation between the severity of the phobia and the degree of gaze avoidance. However, no difference in gaze avoidance according to subject/picture gender matching was observed. These findings confirm and extend some previous results, and suggest that eye avoidance is a robust marker of persons with social phobia, which could be used as a behavioral phenotype for brain imagery studies on this disorder.

Although it is well established that parietal cortex is important in processing sensorimotor transformations, less is known about the neuronal dynamics of this process in humans. Using magnetoencephalography, we investigated the dynamics of parietal oscillatory activity during saccade planning in terms of sensory and motor goal processing. In the experiments, a peripheral stimulus was flashed in either the left or right hemifield, followed by a 1.5 s delay period, after which the subject executed a saccade toward (prosaccade) or away from (antisaccade) the stimulus. In response to stimulus presentation, we observed an initial increase in gamma-band power (40–120 Hz) in a region in the posterior parietal cortex contralateral to the direction of the stimulus. This lateralized power enhancement, which was sustained in a more narrow frequency band (85–105 Hz) during the delay period of prosaccades, mapped to the hemisphere contralateral to the direction of the saccade goal during the delay period of antisaccades. These results suggest that neuronal gamma-band synchronization in parietal cortex represents the planned direction of the saccade, not the memorized stimulus location. In the lower-frequency bands, we observed sustained contralateral alpha (7–13 Hz) power suppression after stimulus presentation in parieto-occipital regions. The dynamics of the alpha band was strongly related to the processing of the stimulus and showed only modest selectivity for the goal of the saccade. We conclude that parietal gamma-band synchronization reflects a mechanism to encode the motor goals in the visuomotor processing for saccades.

International audience; OBJECTIVE: To determine the effect of subthalamic stimulation on visually triggered eye and head movements in patients with Parkinson's disease (PD). METHODS: We compared the gain and latency of visually triggered eye and head movements in 12 patients bilaterally implanted into the subthalamic nucleus (STN) for severe PD and six age-matched control subjects. Visually triggered movements of eye (head restrained), and of eye and head (head unrestrained) were recorded in the absence of dopaminergic medication. Bilateral stimulation was turned OFF and then turned ON with voltage and contact used in chronic setting. The latency was determined from the beginning of initial horizontal eye movements relative to the target onset, and the gain was defined as the ratio of the amplitude of the initial movement to the amplitude of the target movement. RESULTS: Without stimulation, the initiation of the head movement was significantly delayed in patients and the gain of head movement was reduced. Our patients also presented significantly prolonged latencies and hypometry of visually triggered saccades in the head-fixed condition and of gaze in head-free condition. Bilateral STN stimulation with therapeutic parameters improved performance of orienting gaze, eye and head movements towards the controls' level CONCLUSIONS: These results demonstrate that visually triggered saccades and orienting eye-head movements are impaired in the advanced stage of PD. In addition, subthalamic stimulation enhances amplitude and shortens latency of these movements. SIGNIFICANCE: These results are likely explained by alteration of the information processed by the superior colliculus (SC), a pivotal visuomotor structure involved in both voluntary and reflexive saccades. Improvement of movements with stimulation of the STN may be related to its positive input either on the STN-Substantia Nigra-SC pathway or on the parietal cortex-SC pathway.

International audience; INTRODUCTION: We examined the effect of attentional load on attentional capture in schizophrenia. On the basis of the ''resource limitations hypothesis'' in schizophrenia, we propose that attentional capture by an irrelevant distractor will be differentially affected by the attentional load for patients and healthy controls. METHOD: 70 patients with schizophrenia, 15 schizotypals, and 54 controls were asked to attend to a central task while a lateral distractor moved. Participants were instructed either (i) to localise a black square (low-load condition), or (ii) to locate the larger number between two 1-digit numbers (medium-load condition), or (iii) to locate the larger number between two several-digit numbers (high-load condition). In the baseline condition, no distractor moved. RESULTS: All groups showed attentional capture in the low-load condition. Patients and schizotypals resisted interference from the distractor in the medium and highload conditions. Controls resisted interference in the high-load condition. CONCLUSION: The results suggest that attentional modulation is impaired in schizophrenia and in the schizophrenia spectrum.

International audience; This study investigated the link between drivers' gaze positioning and steering behavior when negotiating bends. This was conducted by directing the driver's point of gaze toward a target situated in the vicinity of the tangent point (TP), a region known to attract a significant amount of ocular fixations and thought to provide some useful input for anticipatory steering (M. F. Land & D. N. Lee, 1994). The orientation of gaze relative to the TP was manipulated and the resulting steering behavior was compared to that obtained with a free-gaze strategy. The data revealed that constraining eye movements did not impair steering behavior. On the contrary, the continuous tracking of the fixation point promoted smoother steering control, irrespective of the position of that point. This confirms that previewing the road curvature by tracking a distant point contributes to the stability of steering. The direction of the TP does not appear to be an essential parameter in that process (D. D. Salvucci & R. Gray, 2004). The results also indicate that continuously looking at the TP or further inside the bend yielded a deviation of the trajectory. This is consistent with the hypothesis that drivers look inside the lane boundaries to determine the future path (R. M. Wilkie & J. P. Wann, 2006).

International audience; The perceived strength of darkness enhancement in the centre of surfaces surrounded or not surrounded by illusory contours was investigated as a function of proximity of the constituent elements of the display and their angular size. Magnitude estimation was used to measure the perception of the darkness phenomenon in white-on-grey stimuli. Darkness enhancement was perceived in both types of the stimuli used, but more strongly in the presence of illusory contours. In both cases, perceived darkness enhancement increased with increasing proximity of the constituent parts of the display and with their angular size. These results suggest that the occurrence of darkness (or brightness) enhancement phenomena in the centre of the displays is not directly related to illusory contour formation.

Previous ultra-rapid go/no-go categorization studies with manual responses have demonstrated the remarkable speed and eYciency with which humans process natural scenes. Using a forced-choice saccade task we show here that when two scenes are simultaneously Xashed in the left and right hemiWelds, human participants can reliably make saccades to the side containing an animal in as little as 120 ms. Low level diVerences between target and distractor images were unable to account for these exceptionally fast responses. The results suggest a very fast and unexpected route linking visual processing in the ventral stream with the programming of saccadic eye movements.  2005 Elsevier Ltd. All rights reserved.

Humans are fast and accurate at performing an animal categorization task with natural photographs briefly flashed centrally. Here, this central categorization task is compared to a three position task in which photographs could appear randomly either centrally, or at 3.6 degrees eccentricity (right or left) of the fixation point. A mild behavioral impairment was found with peripheral stimuli with no evidence in support of hemispheric superiority; but enlarging the window of spatial attention to three possible stimuli locations had no behavioral cost on the processing of central images. Performance in the central categorization task has been associated with a large difference between the potentials evoked to target and non-target correct trials, starting about 150 ms after stimulus onset on frontal sites. Present results show that this activity originates within extrastriate visual cortices and probably reflects perceptual stimuli differences processed within areas involved in object recognition. Latencies, slopes, and peak amplitudes of this differential activity were invariant to stimulus position and attentional load. Stimulus location uncertainty and lateralization did not affect speed of visual processing.

International audience; The present study investigated the influence of eye orientation upon the experience of pain. Quasi continuous electrocutaneous stimuli which slowly increased in intensity were delivered to 32 healthy females volunteers. Participants were instructed to direct the eyes at locations that were ipsilateral or contralateral to the stimulated hand. Unpleasantness threshold and pain threshold were significantly higher when the eyes were oriented ipsilateral towards the stimulated hand. In a second experiment phase, the pain intensity increased until tolerance. There was no effect of eye orientation upon pain threshold and tolerance. Results of the first experimental part are in line with the counterintuitive idea that selective monitoring reduces pain distress. The lack of significant results in the second experiment phase is discussed in terms of statistical power and a change in coping induced by the expectation of high intensity pain.

International audience; Lateral shifts in overt attention have been previously shown to modulate reaction times to lateral electrocutaneous stimuli, as well as perception or unpleasantness thresholds. A response bias can play a role in the elicitation of these lateral differences. Therefore, the present experiment aimed at investigating whether eye orientation induces a decision bias in favour of the ipsilateral hemispace. Participants were asked whether or not they suspected subliminal electrocutaneous shocks, whereas no subliminal stimulation was actually delivered. A secondary visual task led participants to direct their eyes ipsi- or contralateral to the stimulated area. Differences between experimental conditions in the amount of subliminal shocks participants acknowledge to receive (number of positive responses) are thought to reflect decision biases. Low and high trait anxiety participants were involved. Results showed an interaction between the eye orientation and the tested hand. The number of positive responses was smaller in right-hand tests with contralateral eye orienting. This effect fits those described previously with real electrocutaneous stimuli. This interaction is related to hemispheric differences in spatial attention. In contrast to thresholds studies, this study failed to replicate that a lateral difference arises in the low but not in the high trait anxiety individuals, suggesting that this interaction was mostly due to the neurosensory processing of the electrocutaneous stimuli.

International audience; Our eyes move constantly, even when we try to fixate our gaze. Fixational eye movements prevent and restore visual loss during fixation, yet the relative impact of each type of fixational eye movement remains controversial. For over five decades, the debate has focused on microsaccades, the fastest and largest fixational eye movements. Some recent studies have concluded that microsaccades counteract visual fading during fixation. Other studies have disputed this idea, contending that microsaccades play no significant role in vision. The disagreement stems from the lack of methods to determine the precise effects of microsaccades on vision versus those of other eye movements, as well as a lack of evidence that microsaccades are relevant to foveal vision. Here we developed a novel generalized method to determine the precise quantified contribution and efficacy of human microsaccades to restoring visibility compared with other eye movements. Our results indicate that microsaccades are the greatest eye movement contributor to the restoration of both foveal and peripheral vision during fixation. Our method to calculate the efficacy and contribution of microsaccades to perception can determine the strength of connection between any two physiological and/or perceptual events, providing a novel and powerful estimate of causal influence; thus, we anticipate wide-ranging applications in neuroscience and beyond.

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The purpose of this study was to examine whether an over-stimulation of the vestibular system, induced by thousands of time saccadic head stimulations, affects the vestibular sensitivity, and consequently if such a phenomenon could contribute to the deterioration of postural stability observed after a long distance running exercise. Eighteen athletic subjects performed a 20.5 km over ground race with an average speed of 15 km.h − 1 , corresponding roughly to 7,500 strides shocks with associated saccadic accelerations transmitted to the head. A preliminary validation of the exercise protocol was realized to confirm the effect of the sustained exercise on body balance by recording standard postural parameters. A visually perceived eye level (VPEL) task was used to indirectly assess otolithic sensitivity motionless or undergoing low centrifugation conditions, before and after exercise. Results obtained from body balance analysis confirmed a decreased postural stability illustrated by increased postural oscillations after the 20.5 km run. Under low centrifugation conditions, results showed a lowering of the VPEL with the increase of the gravito-inertial acceleration in accordance with the literature. However, no significant change in the VPEL after a sustained running exercise was observed. In conclusion, the vestibular sensitivity at the otolithic level does not seem to be altered by an intensive running exercise and then failed to play a key role in the post-exercise deterioration of postural stability.