Dr. Marcus MISSAL
Professeur à l'Université catholique de Louvain.
Institute of Neurosciences IoNs . Groupe COSY.
53 av. Mounier
Boîte B1.53.4 COSY
1200 Bruxelles
Belgique
Research interests:
The neural correlate of anticipatory pursuit movements in the Supplementary Eye Fields.
Anticipatory movements are actions starting before the occurrence of likely sensory events. In an experimental setting, this can be studied by having subjects pursue a moving dot of light appearing on a visual display. If the visual stimulus moves consistently in the same direction during a few presentations, subjects anticipate that it will likely continue to do so during the next presentation and the eyes will start to move in advance of the beginning of the next stimulus appearance. Anticipatory pursuit is a smooth movement of the eye occurring before the appearance of an expected moving target (an example of anticipatory pursuit in human: Anticipation.avi). The expectation of the subject is based on a subjective estimation of the probability that the target will move in a given direction. Although human subjects can be informed of the objective probability that a target will move in a given direction, they tend to rely heavily on past experience to guide their decision to move. Anticipatory pursuit has been extensively studied at the behavioral level. However, the neural mechanisms allowing this important behavior are unknown. Recently, it has been suggested that the SEF could play a role in using past experience to guide anticipatory pursuit. This hypothesis is currently being tested at the single neuron level. Indeed, it has been shown that neurons in the SEF are active during smooth pursuit in the absence of saccades (Heinen 1995), especially when predictable changes in target motion occur (Heinen and Liu 1997). In the behaving monkey, it has been shown that electrical microstimulation in the SEF can facilitate smooth pursuit initiation towards a moving target, suggesting that activation of the SEF might change the internal gain of the smooth pursuit pathway (Missal and Heinen 2001). Expectation of future target events could be altering the internal gain of smooth pursuit. We are currently investigating this hypothesis.
See:
Brainstem physiology.
Causality attribution and anticipatory eye movements.
When viewing one object move after being struck by another, humans perceive that the action of the first object “caused” the motion of the second, not that the two events occurred independently. Although established as a perceptual and linguistic concept, it is not yet known whether the notion of causality exists as a fundamental, preattentional “Gestalt” that can influence predictive motor processes. Therefore, eye movements of human observers were measured while viewing a display in which a launcher impacted a tool to trigger the motion of a second “reaction” target. The reaction target could move either in the direction predicted by transfer of momentum after the collision (“causal”) or in a different direction (“noncausal”), with equal probability. Control trials were also performed with identical target motion, either with a 100 ms time delay between the collision and reactive motion, or without the interposed tool. Subjects made significantly more predictive movements (smooth pursuit and saccades) in the causal direction during standard trials, and smooth pursuit latencies were also shorter overall. These trends were reduced or absent in control trials. In addition, pursuit latencies in the noncausal direction were longer during standard trials than during control trials. The results show that causal context has a strong influence on predictive movements.
Reference:
Jeremy Badler, Philippe Lefèvre, and Marcus Missal (2010)
History of previous scientific positions:
01/10/1989 - 30/09/1992: PhD student, Laboratoire de Neurophysiologie (NEFY), Université Catholique de Louvain (UCL).
01/10/1992 - 30/09/1994: Research assistant UCL, FDS (Fonds de développement scientifique, UCL), Laboratoire de Neurophysiologie.
01/10/1994 - 30/09/1996: Wetenschapelijk medewerker. Kathol. Universiteit Leuven, Laboratorium voor Neuro- en Psychofysiologie.
01/10/1996 - 30/09/1998: Research assistant UCL, Laboratoire de Neurophysiologie, UCL.
01/10/1998 - 30/09/2000: Fellow of the Human Frontier Science Program (HFSP), Smith-Kettlewell Eye Research Institute, San Francisco, CA, USA.
01/10/2000 - 30/09/2001: Fellow of the Smith-Kettlewell Eye Research Institute, San Francisco, CA, USA.
01/10/2001 - 30/09/2002: Scientific collaborator FNRS, Laboratoire de Neurophysiologie, UCL.
30/09/2002 - Present: Chercheur qualifié du FNRS, Professeur chargé de cours UCL.
Scientific awards:
Médaille de l'Académie Royale de Médecine de Belgique. Concours ordinaire régulier de la 1ère Section (1993-1994).
Member of the following societies:
Society for Neuroscience, Neural Control of Movement, Belgian Society for Neuroscience.
Reviewer for the following journals:
Journal of Neuroscience, Journal of Neurophysiology, Experimental Brain Research.
My favorite web sites:
Well-Tempered Clavier: analysis, scores, and digital sound