MOVE

Object recognition in the human medial temporal lobe: latencies from single neurons and local field potentials

This talk will address findings from electrophysiological recordings from the human medial temporal lobe (MTL), compris-ing both clinical depth electrodes and microwires). Recent research has shown that the hippocampus and the entorhinal cortex in humans exhibit independent theta rhythms. The processing of visual stimuli causes a broad-band phase reset of ongoing theta activity in both structures. Single-neurons in the human MTL encode explicit and invariant representations of visual objects. The latencies of these explicit representations are substantially longer that those of a stimulus-related phase reset, indicating a role of this phase reset in the generation of these single-neuron responses. We observed a highly significant correlation between the latency and the selectivity of these neurons: the longer the latency the greater the selectivity. Particularly, parahippocampal neurons were found to respond significantly earlier and less selectively than those in the other three regions. These findings provide direct evidence for hierarchical processing of sensory information at the interface between the visual pathway and the limbic system, by which increasingly refined and specific representations of stimulus identity are generated over time along the anatomic pathways of the MTL.