Laurent Goffart

Verified

Laurent verified their affiliation via an institutional email.

Learn more

Verified

Laurent verified their affiliation via an institutional email.

Learn more

• PhD
• Researcher at French National Centre for Scientific Research

In this article, we perform a critical examination of assumptions which led to assimilate measurements of the movement of a rigid body in the physical world to parameters encoded within the brain activity. In many neurophysiological studies of goal-directed eye movements, equivalence has indeed been made between the kinematics of the eyes or of a t...

The appearance of an object triggers an orienting gaze movement toward its location. The movement consists of a rapid rotation of the eyes, the saccade, which is accompanied by a head rotation if the target eccentricity exceeds the oculomotor range and by a slow eye movement if the target moves. Completing a previous report, we explain the numerous...

At the turn of the 20th century, Henri Poincaré explained that geometry is a convention and that the properties of space and time are the properties of our measuring instruments. Intriguingly, numerous contemporary authors argue that space, time and even number are “encoded” within the brain, as a consequence of evolution, adaptation and natural se...

The appearance of an object triggers an orienting gaze movement toward its location. The movement consists of a rapid rotation of the eyes, the saccade, which is accompanied by a head rotation if the target eccentricity exceeds the oculomotor range; by a slow eye movement if the target moves. Completing a previous report, we explain the numerous po...

Following previous studies documenting the ability to generate anticipatory responses, we tested whether the repeated motion of a visual target along the same path affected its oculomotor tracking. In six rhesus monkeys, we evaluated how the frequency of a target path influenced the onset, the accuracy and velocity of eye movements. Three hundred m...

The caudal fastigial nuclei (cFN) are the output nuclei by which the medio-posterior cerebellum influences the production of saccades toward a visual target. On the basis of the organization of their efferences to the premotor burst neurons and the bilateral control of saccades, the hypothesis was proposed that the same unbalanced activity accounts...

OPEN ACCESS at https://hal.archives-ouvertes.fr/tel-02968991 In their quest for the mechanisms of thought and action, the cognitive and brain sciences consider "space" as an a priori and necessary entity, inherent in the brain functioning. Its nature and neurobiological basis are not questioned. Posited almost like an axiom, this notion is unfortu...

In their quest for the mechanisms of thought and action, the cognitive and brain sciences consider "space" as an a priori and necessary entity, inherent in the brain functioning. Its nature and neurobiological basis are not questioned. Posited almost like an axiom, this notion is unfortunately not defined. Yet the Neurophysiology has made many adva...

Rigorous behavioral studies made in human subjects have shown that small-eccentricity target displacements are associated with increased saccadic reaction times, but the reasons for this remain unclear. Before characterizing the neurophysiological foundations underlying this relationship between the spatial and temporal aspects of saccades, we test...

Rigorous behavioral studies made in human subjects have shown that small-eccentricity target displacements are associated with increased saccadic reaction times, but the reasons for this remain unclear. Before characterizing the neurophysiological foundations underlying this relationship between the spatial and temporal aspects of saccades, we test...

How do we relate observations and measurements made at different levels of complexity ? Notions of kinematics have been used to “decode” the firing rate of neurons and to explain the neurophysiology underlying the generation of visually-guided eye movements. The appropriateness of their fitting to events occurring within a medium (the brain) radica...

Au cours de leur évolution phylogénétique et ontogénétique, les animaux ont été confrontés à la nécessité de gérer un environnement qui n’est pas composé d’objets stationnaires. Dans leur monde, les événements les plus signifiants se produisent souvent quand les choses (animales ou non, prédateur, proie, congénère ou autre) bougent ou quand eux-mêm...

The caudal fastigial nuclei (cFN) are the output nuclei by which the medio-posterior cerebellum influences the production of saccadic and pursuit eye movements. We investigated the consequences of unilateral inactivation on the pursuit eye movement made immediately after an interceptive saccade toward a centrifugal target. We describe here the effe...

The caudal fastigial nuclei (cFN) are the output nuclei by which the medio-posterior cerebellum influences the production of visual saccades. We investigated in two head-restrained monkeys their contribution to the generation of interceptive saccades toward a target moving centrifugally by analyzing the consequences of a unilateral inactivation (10...

Following the suggestion that a command encoding the current target location feeds the oculomotor system during interceptive saccades, we tested the involvement of the deep superior colliculus (dSC). Extracellular activity of 52 saccade-related neurons was recorded in three monkeys while they generated saccades to targets that were static or moving...

When two static visual targets are presented sequentially, the saccades with the shortest latencies land on the location of the first target whereas the later saccades land closer to the second. The transition between the two targets is not abrupt but gradual and continuous. When the two targets are simultaneous, the saccades land on locations situ...

Following the suggestion that a command encoding the expected here-and-now target location feeds the oculomotor system during interceptive saccades, we tested whether this command originates in the deep superior colliculus (SC). Monkeys generated saccades to targets that were static or moving along the preferred axis, away from (outward) or toward...

When two static visual targets are presented sequentially, the saccades with the shortest latencies land on the location of the first target whereas the later saccades land closer to the second. The transition between the two targets is not abrupt but gradual and continuous. When the two targets are simultaneous, the saccades land on locations situ...

Ocular fixation is a dynamic process that is actively controlled by many of the same brain structures involved in the control of eye movements, including the superior colliculus, cerebellum and reticular formation. In this article, we review several aspects of this active control. First, the decision to move the eyes not only depends on target-rela...

The sudden appearance of an object in the visual field triggers an orienting shift of gaze toward its location. This movement consists of an extremely rapid rotation of the two eyes, the saccade. In this article, instead of describing the paths leading from the target-evoked retinal activity to the changes in muscle tension that rotate the eyes, we...

In primates, the appearance of an object moving in the peripheral visual field elicits an interceptive saccade that brings the target image onto the foveae. This foveation is then maintained more or less efficiently by slow pursuit eye movements and subsequent catch-up saccades. Sometimes, the tracking is such that the gaze direction looks spatiote...

Primates heavily rely on their visual system, which exploits signals of graded precision based on the eccentricity of the target in the visual field. The interactions with the environment involve actively selecting and focusing on visual targets or regions of interest, instead of contemplating an omnidirectional visual flow. Eye-movements specifica...

An object moving in the visual field triggers a saccade that brings its image onto the fovea. It is followed by a combination of slow eye movements and catch-up saccades that try to keep the target image on the fovea as long as possible. The accuracy of this ability to track the “here-and-now” location of a visual target contrasts with the spatiote...

The sudden appearance of an object in the visual field triggers an orienting shift of gaze toward its location. This movement consists of an extremely rapid rotation of the two eyes, the saccade. In this article, instead of describing the paths leading from the target-evoked retinal activity to the changes in muscle tension that rotate the eyes, we...

Following the suggestion that a dynamic command encoding the expected here-and-now target location feeds the oculomotor system during interceptive saccades, we tested whether this command originates in the deep superior colliculus (SC). Three monkeys generated saccades to targets which were static or moved along the preferred axis, away from (outwa...

The superior colliculus (SC) is a brainstem structure at the crossroad of multiple functional pathways. Several neurophysiological studies suggest that the population of active neurons in the SC encodes the location of a visual target to foveate, pursue or attend to. Although extensive research has been carried out on computational modeling, most o...

A target that moves smoothly and continuously in the visual periphery triggers interceptive saccades that bring its image within the central field. Thus, the saccades increase the population of neurons (e.g., in the cerebral cortex) whose activity correlates with the visual presence of the object, facilitating its foveal pursuit. This foveation is...

Unlabelled: When an object moves in the visual field, its motion evokes a streak of activity on the retina and the incoming retinal signals lead to robust oculomotor commands because corrections are observed if the trajectory of the interceptive saccade is perturbed by a microstimulation in the superior colliculus. The present study complements a...

A target moving in the visual field triggers an interceptive saccade that brings the target image onto the fovea. This foveation is maintained more or less efficiently by two types of tracking eye movements: low-velocity movements (pursuit) and catch-up saccades. Fleuriet & Goffart (2012) hypothesized that the oculomotor system is driven by an esti...

It is commonly believed that the visual motion signals are used to predict the future position of a moving target. Yet, the signals that drive the oculomotor system actually correspond to an estimate of target position expected here-and-now rather than an estimate of any undefined future position (Fleuriet & Goffart 2012). Therefore, we searched fo...

The neural representation of a moving target undergoes a spatiotemporal “diffusion” while the associated retinal activity propagates toward the motor centers and recruits the appropriate muscles for its interception in the external world. Indeed, the divergent projections within the visual system and the transmissions of signals through multiple re...

During visual fixation, the image of an object is maintained within the fovea. Previous studies have shown that such maintenance involves the deep superior colliculus (dSC). However, the mechanisms by which the dSC supports visual fixation remain controversial. According to one view, activity in the rostral dSC maintains gaze direction by preventin...

Animals can make saccadic eye movements to intercept a moving object at the right place and time. Such interceptive saccades indicate that, despite variable sensorimotor delays, the brain is able to estimate the current spatiotemporal (hic et nunc) coordinates of a target at saccade end. The present work further tests the robustness of this estimat...

When generating a saccade toward a moving target, the target displacement that occurs during the period spanning from its detection to the saccade end must be taken into account to accurately foveate the target and to initiate its pursuit. Previous studies have shown that these saccades are characterized by a lower peak velocity and a prolonged dec...

When primates maintain their gaze directed toward a visual target (visual fixation), their eyes display a combination of miniature fast and slow movements. An involvement of the cerebellum in visual fixation is indicated by the severe gaze instabilities observed in patients suffering from cerebellar lesions. Recent studies in non-human primates hav...

The sudden appearance of an object in the visual field triggers an orienting shift of the line of sight toward its location. This movement consists of an extremely rapid rotation of the two eyes, the saccade. In this article, instead of describing the path leading from the target-evoked retinal activity to the changes in muscle tension that rotate...

It has been shown that inactivation of the caudal fastigial nucleus (cFN) by local injection of muscimol leads to inaccurate gaze shifts in the head-unrestrained monkey and that the gaze dysmetria is primarily due to changes in the horizontal amplitude of eye saccades in the orbit. Moreover, changes in the relationship between amplitude and duratio...

During fixation, the eyes are not still but often exhibit microsaccadic movements. The function of microsaccades is controversial, largely because the neural mechanisms responsible for their generation are unknown. Here, we show that the superior colliculus (SC), a retinotopically organized structure involved in voluntary-saccade target selection,...

The primate superior colliculus (SC) is often viewed as composed of two distinct motor zones with complementary functions: a peripheral region that helps generate saccades to eccentric targets and a central one that maintains fixation by suppressing saccades. Here, we directly tested the alternative interpretation that topography in the SC is not s...

The effects of unilateral cFN inactivation on horizontal and vertical gaze shifts generated from a central target toward peripheral ones were tested in two head unrestrained monkeys. After muscimol injection, the eye component was hypermetric during ipsilesional gaze shifts, hypometric during contralesional ones and deviated toward the injected sid...

The influence of background illumination on saccades towards small target LEDs was examined in three rhesus monkeys. In darkness, fixational saccades and those aimed at horizontal targets had a trajectory that was biased upward. This bias was not observed in the illuminated condition. For horizontal saccades, the magnitude of the vertical final err...

Lesions in the caudal fastigial nucleus (cFN) severely impair the accuracy of visually guided saccades in the head-restrained monkey. Is the saccade dysmetria a central perturbation in issuing commands for orienting gaze (eye in space) or is it a more peripheral impairment in generating oculomotor commands? This question was investigated in two hea...

L’orientation saccadique du regard est le comportement par lequel l’animal explore le monde autour de lui. L’objectif de cet article est de montrer comment la neurophysiologie révèle petit à petit la formidable organisation qui sous tend ce comportement fondamental pour la cognition spatiale. Cette recherche effectuée chez l’animal illustre la néce...

The caudal fastigial nucleus (cFN) is a major nucleus by which the cerebellum influences the accuracy of saccades. In head-restrained monkeys generating saccades from a fixation light-emitting diode (LED) toward a flashed target LED, we analyzed the effects of unilateral pharmacological inactivation of cFN on horizontal, vertical, and oblique sacca...

The production of a goal‐directed saccadic gaze shift involves the specification of movement amplitude and direction, and the decision to trigger the movement. Behavioural and neurophysiological data suggest that these two functions involve separate processes which may interact. The medio‐posterior cerebellar areas are classically assigned a major...

The caudal fastigial nucleus (cFN) is the output nucleus by which the medioposterior cerebellum influences the brainstem saccade generator. In the monkey, inactivation of one cFN by local injection of muscimol impairs all saccades: ipsiversive saccades become hypermetric, contraversive saccades become hypometric, and saccades aimed at a target loca...

The contribution of the cerebellar vermal lobules Vic/VII and of the caudal part of the fastigial nucleus (cFN) to the control of saccadic eye movements has been established by converging neurophysiological approaches. The precise delineation of these saccade-related territories in the medio-posterior cerebellum (MPC) has stimulated the development...

The cerebellar areas involved in the control of saccades have recently been identified in the medio-posterior cerebellum (MPC). Unit activity recordings, experimental lesions and electrical microstimulation of this region in cats and monkeys have provided a considerable amount of data and allowed the development of new computational models. In this...

This document contains the author index of the 16th European Conference on Eye Movements, August 21-25 2011 in Marseille, France

This document contains all abstracts of the 16th European Conference on Eye Movements, August 21-25 2011 in Marseille, France. It was a real honour and a great pleasure to welcome more than 500 delegates to Marseille for the 16th edition of the European Conference on Eye Movements. The series of ECEM conferences started in 1981 under the auspices...

A method for constructing a simple, durable injection-microelectrode (injectrode) is described. The injectrode can record neuronal activity, stimulate neuronal tissues, or inject substances locally through its tip. The injectrode is lightweight and is easy to construct from commercially available parts, and it can be used repeatedly for multiple re...

During the course of previous recordings of visually-triggered gaze shifts in the head-unrestrained cat, we occasionally observed small head movements which preceded the initiation of the saccadic eye/head gaze shift toward a visual target. These early head movements (EHMs) were directed toward the target and occurred with a probability varying bet...

It is known that the medio-posterior cerebellar lobules VI/VII of the vermis and caudal part of the fastigial nucleus (cFN) are involved in the control of saccadic displacements of the visual axis in space (gaze). We have recently shown in the head-unrestrained cat that inactivation of the cFN severely impairs the accuracy of orienting gaze shifts...

Le cervelet médio-postérieur joue un rôle critique dans le contrôle des mouvements saccadiques oculaires vers une cible visuelle. Son dysfonctionnement perturbe sévèrement l'amplitude de toutes les saccades : les saccades sont dysmétriques. Le Noyau Fastigial caudal (NFc) est le noyau de sortie par lequel s'exerce ce contrôle cérébelleux. Son activ...

In the model proposed by Findlay & Walker, the programming of saccadic eye movements is achieved by two parallel processes, one dedicated to the coding of saccade metrics (Where) and the other controlling saccade initiation (When). One outcome of the “winner-take-all” characteristics of the salience map, the main node of the model, is an independen...

The implication of the caudal part of the fastigial nucleus (cFN) in the control of saccadic shifts of the visual axis is now well established. In contrast a possible involvement of the rostral part of the fastigial nuceus (rFN) remains unknown. In the current study we investigated in the head-unrestrained cat the contribution of the rFN to the con...

Muscimol injection in the caudal part of the fastigial nucleus (cFN) leads, in the head-unrestrained cat, to a characteristic dysmetria of saccadic gaze shifts toward visual targets. The goal of the current study was to test whether this pharmacological cFN inactivation impaired the ability to compensate for unexpected perturbations in gaze positio...

The cerebellar control of orienting behavior toward visual targets was studied in the head-unrestrained cat by analyzing the deficits of saccadic gaze shifts after unilateral injection of muscimol in the caudal part of the fastigial nucleus (cFN). Gaze shifts are rendered strongly inaccurate by muscimol cFN inactivation. The characteristics of gaze...

We have shown in the companion paper that muscimol injection in the caudal part of the fastigial nucleus (cFN) consistently leads to dysmetria of visually triggered gaze shifts that depends on movement direction. Based on the observations of a constant error and misdirected movements toward the inactivated side, we have proposed that the cFN contri...

1. The production of a goal-directed saccadic gaze shift involves the specification of movement amplitude and direction, and the decision to trigger the movement. Behavioural and neurophysiological data suggest that these two functions involve separate processes which may interact. 2. The medio-posterior cerebellar areas are classically assigned a...

We investigated whether short-term saccadic adaptation modifies hand pointing. Subjects were presented with double-step targets, the second target jump occurring during the saccade to the first one and bringing the target back to 66% of the first target eccentricity, in order to reduce the gain of their gaze saccades. Before and after this adaptati...

Prior studies have led to the gaze feedback hypothesis, which states that quick orienting movements of the visual axis (gaze shifts) are controlled by a feedback system. We have previously provided evidence for this hypothesis by extending the original study of Mays and Sparks (1980) to the cat with unrestrained head (Pélisson et al. 1989). We show...

1. Cerebellar saccadic dysmetria may result from a disturbance in the processes that ensure correct execution of gaze displacement. Alternatively, an impairment in the preparatory processes that lead to the specification of the movement goal may also produce this deficit. 2. We report here on a pharmacologically induced dysmetria that suggests a ce...

Cat eye movements were recorded during wakefulness and paradoxical sleep with the technique of the scleral search coil in a magnetic field. During waking, eye movements consisted of a succession of saccades and fixation phases. During paradoxical sleep, the pattern of eye movements displayed drifts of variable velocity and direction and short fixat...