Parallel fiber receptive fields: a key to understanding cerebellar operation and learning.

In several theories of the function of the cerebellum in motor control, the mossy-fiber-parallel fiber input has been suggested to provide information used in the control of ongoing movements whereas the role of climbing fibers is to induce plastic changes of parallel fiber (PF) synapses on Purkinje cells. From studies of climbing fibers during the last few decades, we have gained detailed knowledge about the zonal and microzonal organization of the cerebellar cortex and the information carried by climbing fibers. However, properties of the PF input to Purkinje cells and inhibitory interneurones have been largely unknown. The present review, which focuses on the C3 zone of the cerebellar anterior lobe, will present and discuss recent data of the cutaneous PF input to Purkinje cells, interneurons and Golgi cells as well as novel forms of PF plasticity.