Anatomy Department Neuroscience Seminar Series

1 Mar 2011

Abstract

Cerebellum is Latin for 'little brain',  however the cerebellum contains over halfof the total number of neurons in our brain. If it follows that size matters, it isobviously a very important structure. Traditionally, the cerebellum was thoughtto be involved in motor coordination and little else. However, in the last 20years, we have discovered that the cerebellum plays a role in everything fromvisual processing to attention and even higher cognitive functions like emotion.The more we study the cerebellum, the more we discover we know very littleabout its complexity. In Nissl stained tissue sections, the cerebellar cortexdisplays a uniform morphology throughout and lacks distinguishing boundaries.However, if we look closer, at the expression of various molecules, theanatomical connections and the type of stimuli that elicit physiological responsesin the cerebellum, we see very specific patterns. The cerebellum is organized into a series of parasagittal zones. One well studied pattern in the cerebellumcomes from a molecule which is expressed in a subset of Purkinje cells creatinga striped pattern in the cerebellum. This molecule was named Zebrin becausethese stripes reminded the researches of zebra stripes. We now know of over 20different molecules that label a striped pattern in the cerebellum, some of themoverlapping, some opposite, and some with seemingly no relationship. We alsoknow that cerebellar afferent input is organized in a zonal pattern, as well asPurkinje cell electrophysiological response properties. But how do all thesepatterns relate to each other and what causes this parasagittal organization?  How does this organization transform a simple uniform morphology into a complex working cerebellum and allow for the cerebellums involvement in many more functions then we have historically given it credit for.