نبذة مختصرة : Spatial navigation. Beneath these two words, lie a multitude of cognitive processes that operate in our daily lives, each manifesting through distinct behaviours and specific neural activities. Those processes have been classified into different strategies, which rely to varying degrees on the integration, or “surveying”, of the spatial coordinates of every element in the environment, including one’s own position in a cognitive map. At the neuronal level, this position encoding, referred to as “allocentric”, is manifested through the rat place, grid and head-direction cells. However, the model of the metric cognitive map faces contradictions, arising on one hand from the poor performances of humans in orientation tests, and on the other from the differing exploration strategies between rodents and primates, that analyse their environment remotely, through gaze. Moreover, lesion and inactivation studies targeting the hippocampus (HPC), presumed seat of the cognitive map, overall fail to fully disrupt navigation in subjects This implies that other structures, upstream would also play a critical part in spatial navigation. The posterior parietal cortex (PPC) is a good candidate for such role, since its lesion results in hemispatial neglect syndromes and route-based wayfinding impairments. We directed our interest toward VIP and LIP (ventral and lateral intraparietal areas), multimodal associative areas that play a role in the continuous and unified perception of space, as well as in the programming of ocular saccades in link with attention and motivation, that have, nevertheless, never been recorded during goal-directed navigation. Hence, the following questions have been the focus of this thesis: 1) what are the navigation strategies used by primates during a memory spatial task? 2) is the macaque an appropriate model for the study of spatial navigation? 3) how is hippocampal activity linked to visual exploration in primates? 4) how are sensory signals represented in the PPC to ultimately give rise to place-like ...
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