Linking past to future: contributions of awake hippocampal replay to learning

Memories of past experiences influence how we view the present and how we make predictions about the future. The brain is welltuned to capture and translate precise information about experiences into a set of memory traces arranged in a network of distributed connections. During periods of immobility and sleep, the brain is actively reactivating previously stored memories as evidenced by internally-generated patterns of neuronal activity that reflect recent experiences. These “replay” events are believed to strengthen the integration of new knowledge into the brain’s memory store and support simulation of possible future actions. We aim to elucidate how the expression of internally generated hippocampal replay events, embedded in hippocampal ripples, contribute to neocortical replay, and eventually to the consolidation of memory in the neocortex. For this, we will first detect hippocampal ripples and then immediately perturb prefrontal replay events selectively as a way to probe their specific role in learning. We will further study, through optogenetic silencing, whether and how the hippocampal replay is transferred and integrated to neocortical replay, and eventually consolidated into the neocortex