Reorganization of Hippocampal Place-Selective Patterns During Goal-Directed Learning and Their Reactivation During Sleep

Firing patterns of hippocampal principal cells are thought to participate in the formation of mnemonic representations of place, which ultimately can be used to guide the behavior of animals in space. Past studies have suggested that place-selective activity in the hippocampus can emphasize the representation of discrete locations associated with a strong behavioral salience. In the first part of this book chapter, we review work that has described how that hippocampal neuronal activity patterns reorganize during spatial learning. These studies revealed that new hippocampal maps emerge during spatial learning to represent the location of goal locations and demonstrated that, during recall, the reinstatement of these maps predicts successful memory performance. In the second part of this chapter, we discuss the role of sleep in memory consolidation in the context of goal-oriented spatial learning. We summarize work that has demonstrated the replay of goal-oriented neuronal assembly patterns that predict subsequent memory recall. Moreover, we argue that the initial strengthening of new maps may in fact take place during learning, triggered by waking sharp-wave/ripple patterns occurring at goal locations. These reviewed studies highlight that the reorganization and replay of place cell firing patterns might constitute a circuit signature for the expression of newly acquired hippocampal engrams.