Séminaire ISCMJ par Uta Noppeney

Mercredi, 21 Juin, 2017 - 11:00

Suliann Ben Hamed est ravie de recevoir Prof. Uta Noppeney de l'Université de Birmingham, elle donnera une conférence sur:

L'intégration audiovisuelle dans la hiérarchie corticale.

To form a coherent percept of the environment the brain needs to integrate sensory signals from a common source and segregate those from different sources. The ubiquity of multisensory influences at all stages of cortical processing requires us to move beyond designating an area as multisensory towards characterizing its functional characteristics and computational operations. In the first part, I will explore the potential of laminar analyses of 7T fMRI to characterize the neural mechanisms underlying multisensory and attentional influences at the primary cortical level. Laminar activation profiles reveal different mechanisms for multisensory influences operating from vision to audition and vice versa as well as top-down attentional influences. In the second part, I will focus on how the human brain arbitrates between sensory integration and segregation in the face of uncertainty about the world’s causal structure. Combining Bayesian modeling, multivariate decoding and EEG/fMRI we show that the brain integrates sensory signals in line with Bayesian Causal Inference by encoding multiple perceptual estimates along the cortical hierarchy. Only at the top of the hierarchy, in anterior intraparietal sulcus, at about 300-500 ms the uncertainty about the world’s causal structure is taken into account and sensory signals are combined weighted by their sensory reliabilities and task-relevance as predicted by models of Bayesian Causal Inference. Informed by causal inference in dorsolateral prefrontal cortex, the intraparietal sulcus generates audiovisual spatial representations to guide behavioural choices and motor responses. IPS also enables recalibration of auditory spatial representations in planum temporale to reconcile persistent sensory discrepancies.

Salle du Conseil de l'ISCMJ - à partir de 11h