A neural code for spatiotemporal context

Abstract

Time and space are principle organizing dimensions of human experience. Whereas separate lines of study have identified neural correlates of time and space, little is known about how these representations converge during self-guided experience. Here we asked how neurons in the human brain represent time and space concurrently. Subjects fitted with intracranial microelectrodes played a timed navigation game where they alternated between searching for and retrieving objects in a virtual environment. Significant proportions of both time- and place-selective neurons were present during navigation, and distinct time-selective neurons appeared during task-free delays absent movement. We find that temporal and spatial codes are dissociable, with time cells remapping between search and retrieval tasks while place cells maintained stable firing fields. Other neurons tracked the context unique to each task phase, independent of time or space. Together these neuronal classes comprise a biological basis for the cognitive map of spatiotemporal context.