A single microcircuit with multiple functions: state dependent information processing in the hippocampus

Many neural circuits process information in multiple distinct modes. For example, the hippocampus is involved in memory encoding, retrieval, and consolidation processes. These different mnemonic computations require processing of differing balances of current sensory input and previously stored associations. Here we explore patterns of activity in hippocampal output area CA1 associated with different information processing states. We discuss the evidence linking these patterns to specific inputs to CA1 and describe behavioral factors that are related to the balance of synaptic drive. We suggest that understanding the factors that influence information flow in the hippocampal circuit could provide important new insights into how neural circuits are reconfigured on the fly to perform different functions at different times.

► The hippocampal circuit is critical for multiple memory functions. ► These functions depend on different patterns of drive to output area CA1. ► Patterns of drive change on a moment-by-moment basis during learning. ► The balance of EC/CA2 and CA3 drive of CA1 may set network state and function.