Inhibitory neuronal networks are important for brain function, and one of the brain regions where inhibition is well-known to play a pivotal role is the cerebellum. In the cerebellar cortex, GABAergic inhibitory interneurons located in molecular layer
coordinate motor behavior by providing inhibitory inputs to Purkinje cells, the sole output neurons of the cerebellar cortex. Each molecular layer interneuron projects to several different Purkinje cells (divergence) and each Purkinje cell receives input from several individual interneurons (convergence). Although the general anatomical features of cerebellar circuits are relatively well defined, little is known about their spatial organization. For this project I will study the divergence of this circuit. I will study this by: (1) observing the activity of a population of Purkinje cells in response to photostimulation of individual molecular layer inhibitory neurons, by optogenetic stimulation of molecular layer interneurons and voltage-sensitive dye imaging; and (2) examine how the organization of interneuron-Purkinje cell connections varies across cerebellar compartments. This approach will permit a quantitative description of the spatial organization of circuits between inhibitory neurons and Purkinje cells, paving the way for a deeper understanding of the functional dynamics of information processing
by the cerebellum.