Modulation of memory consolidation by optogenetic induction of spindles and down-states in mice

During wakefulness, the brain receives and integrates a great deal of information from its environment, producing patterns of neuron activation in several cerebral structures. During sleep, all these patterns are replayed, generating phase-specific oscillations. It is during non-REM sleep that down-states and spindles are generated by the thalamus. Another oscillation is also generated by the hippocampus: sharp wave ripples. These 3 oscillations will help to consolidate memory.

 

Down-states are an active process responsible for synchronising the activity of different brain regions. Spindles open a short window of synaptic plasticity across the whole cortex. And finally, sharp wave ripples are essential for the transition from short-term memory (provided by the hippocampus) to long-term memory (provided by the cortex). In addition, the thalamus is a structure of choice for studying this consolidation of long-term memory because it receives and sends projections from the hippocampus and the various cortices.  This communication between these structures will enable the formation of long-term association memory of different sensory information from several cortical areas.

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The aim of my internship will be to use optogenetic stimulation of the thalamus to check whether the induction of down-states or spindles throughout the cortex after the natural generation of sharp wave ripples in the hippocampus will have a positive or negative effect on the memory consolidation effect using behavioural tests.