Dreaming in context – Role of context in sensory cortico-hippocampal interactions during consolidation

In sleep, neural activity patterns associated with learned behaviours are reactivated, consolidating the fragile memory traces established during the day. The standard view is that reactivation begins in hippocampus and spreads to downstream higher order cortices. Compared to higher order cortical consolidation, little is known about memory consolidation in upstream sensory cortices. Here reactivation precedes, rather than follows, that in hippocampus, raising fundamental questions about the role of hippocampus in this consolidation. We hypothesize that sensory memory representation is influenced by hippocampus-dependent relational/spatial context. To test this hypothesis, we will use sounds to study learning-associated reactivation in primary auditory cortex and hippocampus and its effect on memory representation. Taking advantage of state-of-the-art high-density Neuropixels probes and optogenetics we will sample neural activity in all cortical layers and hippocampus of behaving and sleeping mice. The combination of these approaches will allow us to explore how reactivation and cortico-hippocampal interactions depend on acoustic (work package 1), spatial (WP2), and schema (WP3) contextual information, with the aim to better understand sensory consolidation, and its connection with neuronal representation.

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