Sequence and Place Interplay for space Coding, in Epilepsy and Dystonia – SPICED

Even in a familiar city, we may get momentarily lost when exploring districts we had never visited before. Have you ever stumbled into a known place completely unexpectedly and felt that the whole environment had to be reorganized and reoriented to fit the representation you had?
Our project questions whether the striatum or the hippocampus, two cerebral structures involved in memory and navigation, could trigger the strategy switches occurring when external information does not match our internal representation anymore. We hypothesize that the used of these strategies reflect a computational choice between two functioning modes of the navigation and memory systems: A “memory-driven” mode in which the hippocampo-striatal circuit mainly uses self-motion monitoring to update self-location with respect to our internal representation of the environment, and a “senses-driven” mode in which the striatum and hippocampus retrieve allothetic information to (re-)anchor behavior and internal representations with respect to external landmarks. To address this question we will take advantage of deep brain electrodes implanted around the hippocampus for pre-surgical assessment in patients with epilepsy, or in the globus pallidus, output of the striatum, for therapeutic stimulation purpose in patients with dystonia. We also stimulate the cerebellum, a structure functionally connected to the striatum and the hippocampus. We hypothesize it may have an impact on the choice of one strategy over another, and thus possibly facilitate learning in a navigation task. Hopefully such cerebellar stimulation may be able to enhance the motor and spatial memory often affected in these pathologies.