Département de Médecine, Unité de Physiologie
Université de Fribourg (Suisse)
Multisensory and motor integration in the non human primate:
anatomical, behavioral and electrophysiological approaches
Céline Cappe
Thèse en co-tutelle avec l’Université Paul Sabatier, F-Toulouse III
In order to interact with the multimodal world which surrounds us, we must integrate simultaneously
various sources of sensory information (vision, hearing, body sensation…). A fundamental question is
thus to know how the brain integrates the separate elements of an object defined by several sensory
components to form a unified percept. The superior colliculus was the main model to study the
polymodal integration. At the cortical level, until recently, polymodal integration appeared to be a
characteristic that only had the associative areas located at the top of the information processing
hierarchy. First of all, our first study related to cortico-cortical connections and showed the existence
of direct projections between cortical areas of different sensorialities in the non human primate. Then,
the study of projections between different sensory and motor cortical areas and the thalamus enabled
us to highlight the existence of thalamic nuclei which, by their connections, could represent an
alternative pathway for the information transfer of different sensory and/or motor cortical areas. The
thalamus could allow a faster transfer and even an integration of information. In addition, at the
behavioral level, multisensory integration allows an improvement of perception. An experiment
conducted in macaques monkeys in a detection task of unimodal and bimodal stimuli showed the
presence of a significant multisensory gain which is highest at threshold level, which decreases for
increasing intensities above threshold and which disappears at high intensities. Lastly, in these
animals showing this multisensory gain on the behavorial side, we explored the mechanisms
underlying multisensory integration at the neuronal level in the auditory cortex. Thus, using
anatomical, behavioral and electrophysiological approaches, our results provide fundamental
elements on the cerebral structures implied in multisensory integration, their connections and the
mechanisms existing in the brain to treat in an effective way different sensory information, in order to
initiate a motor response.
Keywords: multisensory and motor integration, cortico-cortical connections, connections between the
cortex and the thalamus, behavioral, sensory detection, vision and audition, electrophysiological units
recordings, non human primates.
Jury de thèse: Prof. Eric M. Rouiller (directeur de thèse), Université de Fribourg
Dr. Pascal Barone (co-directeur de thèse), Université Paul Sabatier, F-Toulouse III
Prof. Stéphanie Clarke, (experte externe), CHUV, Lausanne
Prof. Robert Kretz, (expert), Université de Fribourg
Prof. Jean-Michel Lassalle, (président du jury), Université Paul Sabatier, F-Toulouse III