Understanding Motor Networks

Synaptic Circuit Organization of the Rubro-Olivary System
2009 Seed Grant
Gordon Shepherd, M.D., Ph.D.
Northwestern University

In mammals, the control of movement relies on networks of neurons in many different brain regions. A major pathway linking different motor circuit is in the brainstem, linking ‘upstream’ neurons in the red nucleus (RN) to ‘downstream’ neurons in the inferior olive (IO) nucleus. The IO neurons project onward to the cerebellum, which projects back to the RN to form a loop, and RN also receives signals from the cerebral cortex. Pathology of rubro-olivary (RN-to-IO) connectivity causes profound loss of motor control, and degeneration of IO neurons. The rubro-olivary projection is clearly of major importance for motor control, but, remarkably, the actual function of this projection remains highly controversial, especially because of an almost complete lack of data about the connectivity and synaptic physiology underlying this projection. We propose to use a novel combination of cutting-edge circuit analysis tools to elucidate the synaptic organization of the rubro-olivary pathway, as a first step towards developing paradigms for analyzing subcortical motor circuits in general.