Prof. Gilad Silberberg, Department of Neuroscience, Karolinska Institute, Stockholm, Sweden
The striatal microcircuitry consists of the major projecting population, the medium spiny neurons (MSNs), and a diverse population of interneurons. Fast spiking (FS) interneurons provide robust and reliable feed-forward inhibition, targeting both direct and indirect pathway MSNs with high connection probability, and are considered important for the synchronization of their postsynaptic targets. Striatal cholinergic interneurons provide disynaptic inhibition to MSNs and under in vivo conditions display tonic and synchronized discharge. Whether and how FS interneurons control cholinergic interneurons and affect their synchronicity or regulate other striatal interneuron types remains unknown.
We have here combined multiple whole-cell recordings with optogenetics in order to directly characterize the target selectivity of feed-forward inhibition provided by striatal FS interneurons. Using transgenic and viral approaches we have specifically directed expression of ChR2 to FS interneurons to study their connectivity within the striatal microcircuit in acute brain slices. I will also present in-vivo work demonstrating bilateral and multimodal sensory integration by individual striatal projection neurons and interneurons.