Distribution of spinocerebellar Purkinje cell responses to passive forelimb movements in the rat

We recorded Purkinje cell activity throughout the spinocerebellum of anaest hetized rats while imposing circular passive movements to the unrestrained forelimb. The aim was to understand the type of processing of sensory infor mation occurring at the level of the cerebellar cortex, on the basis that p recerebellar sensory neurons have been shown to represent whole limb moveme nt parameters better than single joint movements. We observed that neurons representing sensory aspects of arm movements were scattered throughout the spinocerebellar cortex without a distinct segregation from those that did not respond, albeit the relative density of responsive and unresponsive neu rons was quite variable and depended on the area of the cortex. Furthermore , Purkinje cells that responded significantly to the arm movement cycles al l showed the same response pattern consisting of a firing rate increase dur ing the downward extension of the arm. These results are discussed as sugge sting a coordinate framework for the representation of proprioceptive infor mation in the cerebellum congruent to that observed for encoding motor para meters.