Study of the roles of striatal populations in instrumental learning by optogenetic targeting

Abstract

Event Abstract Back to Event Study of the roles of striatal populations in instrumental learning by optogenetic targeting Muriel Laurent1*, Serge N. Schiffmann1 and Alban De Kerchove D'Exaerde1 1 Université Libre de Bruxelles, ULB Neuroscience Institute, Belgium The basal ganglia, and particularly the dorsal striatum, play a critical role in motor planning and learning processes. The striatum contains a majority of intermingled projection neurons, called the medium spiny neurons (MSN). These MSN are divided in two sub-populations: the striatonigral neurons (forming the direct pathway) and the striatopallidal neurons (forming the indirect pathway). These two parallel basal ganglia pathways exert opposing influences on motor and reward functions[1]. Furthermore, the dorsal striatum can be functionally divided into a medial part (dorsomedial striatum, DMS) and an internal part (dorsolateral striatum, DLS). The aim of our study is to assess the specific contribution of striatal sub-populations in DMS and DLS by selectively manipulating their neuronal activity during operant behaviours. To interrogate this neural circuitry, we are using optogenetic, which allows rapid and reversible control by light of genetically-targeted neural populations at physiological level[2]. First, with our AAV rodent’s models expressing Channelrhodospin2 specifically in both populations, we have shown on living brain slices a specific activation of each neuronal population by light, validating our optogenetic approach. We are using chronic optic fiber implant to deliver light into the brain and we showed that in vivo unilateral optical activation of striatonigral and striatopallidal neurons in the DLS in awake behaving mice induce the predicted turning behaviour. Now, these mice are studied in operant learning paradigms, such as acquisition of serial order, using a two-action sequence task[3]. We showed that activation of both populations in DLS affect the learning of a novel sequence.