Jozsef Csicsvari, Institute of Science and Technology Austria, Klosterneuburg

Hippocampal Reactivation during Spatial Memory Tasks

In the first part I present result that demonstrate the direct involvement of goal-specific reactivation in the stabilisation of spatial memories. To this end we have developed a method that involved the online identification of cell assemblies and the optogenetic disruption of a selective subgroup of them during reactivation. We trained animals to locate goals in two different environmental context (i.e. two cheeseboards at different location with different distal cues), with each associated with a different goal location. After learning we disrupted the reactivation of assemblies representing one of the goals using our online assembly detection procedure during rest/sleep. Following the disruption, we observed a selective memory impairment of the disrupted goal but not the other. Altogether, these results suggest that reactivation of learned goals during sleep has a role in in the consolidation of spatial memories. The second part covers the results of another project where we examined waking reactivated trajectories during three different radial 8-arm maze spatial tasks. We found that waking reactivated trajectories at the decision point in the central stem of the maze predicted the future arm choice of the animal when the task had a reference memory component but not when it was a pure working memory task. This work suggests that waking trajectory reactivation is involved in decision making in a spatial task when a reference memory is needed to be recalled.

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GRK 1589