Motivational State Influences the Content of Hippocampal Sequences

Abstract

Hippocampal sharp wave-ripple (SWR) associated sequence activity, commonly referred to as replay, has generally been thought of as mediating the transfer of recent experience into the neocortex. However, a number of recent studies have shown that the content of sequences is not limited to recent experience. To investigate whether internally generated stimuli, such as appetitive motivational states, affect the content of SWR-associated spiking activity, we recorded from ensembles of CA1 place cells while rats were performing a motivational shift task on a simple T-maze. Rats were food restricted or water restricted on alternating days and trained to make a left turn for food and right turn for water. We found that SWR-associated spiking activity recorded prior to task performance was correlated with motivational state and overall behavioural choices, suggesting that it also mediates retrieval of past behavioural episodes to facilitate planning for motivationally relevant outcomes.