Spatial Locations Decoded By Human Hippocampal Wide-band Signals In A Virtual Navigational Environment

Cognitive map theory suggests that hippocampal neural activity is associated with spatiotemporal coding of the spatial environment.However,researchers are still interested in understanding how hippocampal neuronal signals are decoded and how this decoded information further explains the features of spatial memory backtracking.In recent years,the development of deep learning models has provided a powerful,cross-field approach to decoding neuronal signals to a behavioral dimension.For the first time,we have combined this model with electrophysiological signals from human hippocampal signals to investigate human spatial memory recall strategies characterized by hippocampal neural activity under our specific task.We derived electrophysiological signals from the subjects’ hippocampal brain regions using sEEG(stereotactic EEG)and had them passively navigate along a circular path in a virtual environment interspersed with 20 equidistant objects.This was followed by a distance memory judgment task.Using a deep learning approach,we trained a particular model for each subject by using behavioral versus electrophysiological data during passive navigation as a training set.The model projected electrophysiological signals to the behavioral level,and we projected neuronal signals from the human hippocampus in a distance memory judgment task to a behavioral dimension.We recorded trajectories of how the locations of hippocampal neural activity representations in virtual memory space moved.Our results showed a correlation between decoding location and task performance,with subjects more prone to dense backtracking in the virtual space environment surrounding the correct item on the correct trial.Additionally,we found that location exploration in virtual memory space conforms to the Lévy strategy in physical space.Taken together,our decoding results delineate a navigational cognitive exploration map in the human hippocampus and link spatial retrieval trajectories in virtual memory space to Lévy foraging phenomena in physical space.In summary,our decoding results delineate a navigational cognitive exploration map in the human hippocampus and link spatial retrieval trajectories in virtual memory space to Lévy foraging phenomena in physical space.