Interações hipocampo-prefrontais durante a tomada de decisão espacial

Abstract

The hippocampus has been linked to memory encoding and spatial navigation, while the prefrontal cortex is associated with cognitive functions such as decision-making. These regions are hypothesized to communicate in tasks that demand both spatial navigation and decision-making processes. However, the electrophysiological signatures underlying this communication remain to be better elucidated. To investigate the dynamics of the hippocampal-prefrontal interactions, we have analyzed local field potentials and spikes recorded from rats performing an odor-cued spatial alternation task in an 8-shaped maze. We found that the phase coherence of both theta (6-10 Hz) and beta (23-30 Hz) peaked around the choice point area of the maze. Moreover, Granger causality revealed a hippocampus->prefrontal cortex directionality of information flow at theta frequency, peaking at starting areas of the maze, and on the reverse direction at delta frequency, peaking near the turn onset. Additionally, the patterns of phaseamplitude cross-frequency coupling within and between the regions showed spatial selectivity. Lastly, we found that the theta rhythm dynamically modulated neurons in both regions; interestingly, prefrontal cortex neurons were more strongly modulated by the hippocampal theta rhythm than by its LFP. In all, our results reveal maximum electrophysiological interactions between the hippocampus and the prefrontal cortex near the decision-making period of the spatial alternation task. These results corroborate the hypothesis that a dynamic interplay between these regions takes place during spatial decisions.