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Equilibria and transitions : Neurophysiology of orientation and visuomotor presence

How do activities of interconnected microscopic elements (neurons) enable a macroscopic organism to reach a visual object located in its external physical world ? In other words, how do we relate neuronal activities with kinematic measurements ? How do we relate events which are measured in mediums of different scales and complexity orders ?

During the course of Evolution, most animals were faced with the necessity to cope with a dynamic environment. In the world peculiar to each species (Umwelt), the most significant events happen when things (animal or not, predator, prey, congener or else) move or when they move themselves. Endowed with a sensitivity and a reactivity to motion, the animals managed to interact with the objects of the external world, their interactions consisting of establishing contacts and links around zones of less instabilities; The sensitivity does not resume to the passive contemplation of a streaming landscape ; it is a "combative" engagement, the opportunity for creating spatiotemporally local links, for creating accompaniments, i.e., a sensorimotor presence constituting a relation subject-"object" which is oriented (considering disorientation at the origin of panic reactions and escape).

Our research is aimed at charactering the neurophysiology of this relationship, dynamic and spatial, that an animal establishes with the objects of its visual environment, using the gaze orientation of the monkey as a model for comprehending human neurological disorders and also as an experimental probe. Aware of the stratification of measured phenomenon, we defend the following theoretical viewpoint: the zones of interaction are multipolar equilibria and the movements (saccadic or slow) are their restoration with dynamics which are determined by the intrinsic properties of mobilized sensorimotor channels (Goffart et al. 2018 ; Goffart 2019).

The appearance of an event in the peripheral visual field triggers a transition, a rapid orienting gaze shift (saccade) at the end of which the image of the object becomes more or less well projected onto the retinal area endowed of the greatest visual acuity (the fovea). Thus, brought within the central visual field, the target involves a larger number of neurons. The reached equilibrium is represented by a bilateral cerebral activity whose fluctuations in the superior colliculus are proposed to be the origin of those microsaccades observed during visual fixation (Hafed et al. 2009). We have shown that the symmetry of this unstable equilibrium (Goffart et al. 2012) involves the oculomotor cerebellum through the two caudal fastigial nuclei (Guerrasio et al. 2010). We have also characterized how the neurons of these nuclei intervene in the restoration (saccade) of the equilibrium broken by any symmetrical visual stimulus (Goffart et al. 2004; Quinet & Goffart 2015).

The foveal capture (foveation) also applies to targets that are moving. In this case, for the capture to be accurate, the brain activity must develop signals that correspond to what would be called the "current spatiotemporal coordinates" of the targeted object (Fleuriet et al. 2011). Our works suggest that this neural dynamics defines in the best case, its here-and-now (hic-et-nunc) position (Fleuriet & Goffart 2012; Goffart et al. 2014; Bourrelly et al. 2014, 2015, 2016a,b). How is this physically local and "sharp" representation possible when one considers the multiple delays of neuronal conduction and the distributed encoding of a visual object in the brain? What is the internal structure of this thing that the classical measurements reduce to a point (x,y,z,t)?

Notions of prediction or internal model of the trajectory are sometimes used. But what do these notions mean in neurophysiological language? Our experimental results lead us to consider instead attempts to synchronize with the present and current situation (Bourrelly et al. 2016; Goffart et al. 2017a). The repetition of this visuomotor presence (engagements) yields a dynamic mnemonic "trace" which, in the physical world corresponds to the trajectory, but in the brain activity appears to be a recruitement of resources. We do neither use the notion of prediction because it postulates a notion (the future) which is a cultural concept, likely meaningless at the neuronal level. As a matter of fact, when we study the activity of collicular neurons during interceptive saccades, we discover a "horizon" that does not expand beyond the locus/time of capture (Goffart et al. 2017b). In order to aim at understanding how a memorized experience is being actualized within the action, we prefer to avoid notions of premonition or gamble, and study the construction of sensorimotor schemes which are exact, i.e., efficient for the survival of the macroscopical organism.

Using transient and local perturbation techniques (pharmacological inactivation, microstimulation), this research aims at defining the neuro-functional organization that enables us to generate actions which are spatiotemporally adapted to the on-going external conditions, on the basis of an afferent neuronal dynamics (Quinet & Goffart 2015) and a mnemonic dynamics built upon the past experience but actualized in the on-going action (Bourrelly et al. 2013, 2014, 2015, 2016). We want to understand how this is made possible, neurophysiologically speaking, i.e., to identify the channels and flows of neuronal activity which are hidden behind these multiple shortcuts, often vague and sterile, like internal model, etc., taking care also of avoiding all teleological arguments, even refuting them because we do not think that the nervous system is a "machine" akin to most of those invented by homo faber.

This research is primarily performed in the non-human primate (macaque monkey) in order to identify the underlying neurophysiology and promote the neurology of sensorimotor disorders. Efforts have also been developed to extend it to other animal varieties such as the insect (hyperlien), in collaboration with Drs Y. Yamawaki and T. Carle (Kyushu University, Japan), with the aim to define more fundamentally, with neurobiological terms, the visuomotor presence, i.e., the locus and the instant of sensorimotor interaction which, once again, must not be considered as a point but as a dynamical equilibrium.

A selection of publications :

Synthesis works

Goffart L. Saccadic eye movements: Basic neural processes. Reference Module in Neuroscience and Biobehavioral Psychology 2017. hyperlien

Goffart L, Bourrelly C & Quinet J. Synchronizing the tracking eye movements with the motion of a visual target: basic neural processes. Progress in Brain Research 2017. hyperlien

Goffart L. De la représentation cérébrale spatio-temporellement distribuée à la capture ici-et-maintenant d’un objet visuel en mouvement. In: L’avenir de la complexité et du désordre, Lévy J-C S & Ofman S Editions matériologiques 2018. hyperlien

Goffart L, Bourrelly C & Quinton J-C. Neurophysiology of visually-guided eye movements: Critical review and alternative viewpoint. Journal of Neurophysiology 2018 hyperlien

Goffart L. Kinematics and the neurophysiological study of visually-guided eye movements. Progress in Brain Research 2019 hyperlien

Neural basis of spatiotemporal congruence (here-and-now)

Bourrelly C, Quinet J & Goffart L. Equilibria and transitions during visual tracking: Learning to track a moving visual target in the monkey. Society for Neuroscience Abstracts 2013. hyperlien

Bourrelly C, Quinet J & Goffart L. Unsupervised dynamic morphing of a spatiotemporal visual event during its oculomotor tracking. Journal of Vision 2014. hyperlien

Bourrelly C, Quinet J & Goffart L. Evolution of the oculomotor tracking with an accelerating or decelerating target Journal of Vision 2015. hyperlien

Bourrelly C, Quinet J, Cavanagh P & Goffart L. Learning the trajectory of a moving visual target and evolution of its tracking in the monkey. Journal of Neurophysiology 2016a. hyperlien

Bourrelly C, Quinet J, Cavanagh P & Goffart L. Abstraction of 2D head-centered positions from tracking a moving visual target: A study in the non-human primate. Soc. Neurosci. Abstr. 2016b. hyperlien

Bourrelly C, Quinet J & Goffart L. The caudal fastigial nucleus and the steering of saccades toward a moving visual target. Journal of Neurophysiology 2018. hyperlien

Bourrelly C, Quinet J & Goffart L. Pursuit disorder and saccade dysmetria after caudal fastigial inactivation in the monkey. Journal of Neurophysiology 2018. hyperlien

Fleuriet J & Goffart L. Saccadic interception of a moving visual target after a spatiotemporal perturbation. Journal of Neuroscience 2012. hyperlien

Fleuriet J, Hugues S, Perrinet L & Goffart L. Saccadic foveation of a moving visual target in the rhesus monkey. Journal of Neurophysiology 2011. hyperlien

Goffart L. Parallel and continuous visuomotor processing of simultaneously moving targets.Journal of Vision 2017. abstract hyperlien poster hyperlien

Goffart L, Cecala A & Gandhi N. The superior colliculus and the steering of saccades toward a moving visual target. Journal of Neurophysiology 2017b. hyperlien

Goffart L, Chen LL & Sparks DL. Saccade dysmetria during functional perturbation of the caudal fastigial nucleus in the monkey. Annals of the New York Academy of Sciences 2003. hyperlien

Goffart L, Chen LL & Sparks DL. Deficits in saccades and fixation during muscimol inactivation of the caudal fastigial nucleus in the rhesus monkey. Journal of Neurophysiology 2004. hyperlien

Goffart L & Fleuriet J. Hic-et-nunc (here-and-now) encoding of a moving target for its saccadic foveation. i-Perception 2012. hyperlien

Goffart L & Fleuriet J. Dynamic morphing of a spatiotemporal event for the orienting reaction. In: Ladislav Tauc & GDR MSPC Neurosciences Conference 2010.

Goffart L, Quinet J & Bourrelly C. Foveating a moving target, here-and-now. Journal of Vision 2014. hyperlien

Hafed ZM, Goffart L, Krauzlis RJ. Superior colliculus inactivation causes stable offsets in eye position during tracking. Journal of Neuroscience 2008. hyperlien

Quinet J & Goffart L. Head unrestrained gaze shifts after muscimol injection in the caudal fastigial nucleus of the monkey. Journal of Neurophysiology 2007. hyperlien

Quinet J & Goffart L. Electrical microstimulation of the fastigial oculomotor region in the head unrestrained monkey. Journal of Neurophysiology 2009. hyperlien

Quinet J & Goffart L. Cerebellar control of saccade dynamics: contribution of the fastigial oculomotor region. Journal of Neurophysiology 2015. hyperlien

Quinet J & Goffart L. Does the brain extrapolate the position of a transient moving target? Journal of Neuroscience 2015. hyperlien

Quinton J-C & Goffart L. A unified neural field model of the dynamics of goal-directed eye movements. Connection Science 30: 20-52, 2018. hyperlien

Visual fixation as unstable equilibrium

Goffart L, Hafed ZM & Krauzlis RJ. Visual fixation as equilibrium: evidence from rostral superior colliculus inactivation. Journal of Neuroscience 2012. hyperlien

Goffart L, Quinet J, Chavane F & Masson GS Influence of background illumination on fixation and visually guided saccades in the rhesus monkey. Vision Research 2006. hyperlien

Guerrasio L, Quinet J, Büttner U & Goffart L. The fastigial oculomotor region and the control of foveation during fixation. Journal of Neurophysiology 2010. hyperlien

Hafed ZM, Goffart L, Krauzlis RJ. Superior colliculus inactivation causes stable offsets in eye position during tracking. Journal of Neuroscience 2008. hyperlien

Hafed ZM, Goffart L & Krauzlis RJ. A neural mechanism for microsaccade generation in the primate superior colliculus. Science 2009. hyperlien

Taouali W, Goffart L, Alexandre F & Rougier N. A parsimonious computational model of visual target position encoding in the superior colliculus. Biological Cybernetics 2015. hyperlien

Krauzlis R, Goffart L. & Hafed ZM (2017) Neuronal control of fixation and fixational eye movements. Philosophical Transactions of the Royal Society B, 20160205, 2017.

Internet links:

ORCID : 0000-0001-8767-1867


Goffart L. Brain processes for foveating a visual target here-and-now. Séminaire Los Angeles UCLA 2016: hyperlien

Goffart L. Neural processes underlying the accurate foveation and tracking of a visual target. Séminaire pour Kolloquium der Abteilung Allgemeine Psychologie/ Current Topics in Perception and Cognition, Prof. Karl Gegenfurtner, Giessen, Allemagne, 2018. hyperlien




Biography :

  • 2016: master degree in History and Philosophy of Fundamental Sciences (Aix-Marseille Université); Research report: Contribution critique à la recherche des fondements neuro-psycho-physiologiques de la notion d’espace (Prof. G. Crocco, Dr I. Ly)
  • 1996: Philosophiae Doctor in Neurosciences (Claude Bernard University Lyon I); Thesis: L’orientation saccadique du regard vers une cible: étude de la contribution du cervelet médio-postérieur chez le chat en condition "tête libre" no 70-96 (Committee: Prof. W. Becker, Prof. A. Berthoz, Prof. J.M. Coquery, Dr G. Gauthier, Prof. M. Jeannerod, Dr D. Pelisson, Prof. A. Roucoux)
  • 1991: master degree in Physiology (Lille University of Science and Technology - Lille I)
  • 1990: master degree in Psychology (Charles de Gaulle University – Lille III); Research report: Posture oculaire et facilitation cutanée du réflexe de Hoffmann (Prof. J.M. Coquery, Dr J. Honoré)

My scientific engagement starts in 1983 with the discovery of the kantian conceptions of space (S), time (T) and knowledge acquisition. The piagetian constructivism, the catastroph theory and the Physiology led me to focus on the saccadic orienting reaction and to the morphogenesis. Pellionisz-Llinas (1982) was seminal in my search for the neurobiological foundations of S & T. The reflections of Henri Poincaré lead to the idea that these notions might merely be social conventions (concepts): S-T are then being replaced by a "lattice" of neuronal activation trajectories "weaved" (or "paved") by processes triggered whenever an external object is captured (contact here-and-now).

Current perspectives: learning, memory, real-time immersion, dynamic morphing, neuro-epistemology, sensorimotor presence, contact, link, spatial synchronization ...

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