Fig. 1.

Schematic of the cerebellar circuit shown in sagittal and coronal planes. Climbing fibers, originating in the inferior olive, form excitatory synapses on the dendrites of Purkinje neurons (green). Mossy fibers, which originate in multiple hindbrain and spinal cord nuclei, form excitatory synapses on granule neurons (red) in the cerebellar cortex. The granule cells, in turn, project parallel fiber axons into the molecular layer and form excitatory synapses on the dendrites of Purkinje neurons. Stellate and basket cells (blue), in contrast, form inhibitory synapses on Purkinje neurons, the sole output of the cerebellar cortex, which project inhibitory axons to the deep cerebellar nuclei