Microelectrode study of dorsal spino-cerebellar tract.

Abstract

The dorsal spinocerebellar tract (DSCT) at C-1, C-2, and the lower medulla level was studied with microelectrodes in lightly anesthetized cats. All responses were obtained from the stimulation of the ipsilateral side of the body. The sensory modalities activating the total of 242 fibers studied were touch (53%), pressure (31%), touch and pressure (2%), and joint movement (14%). Responses to touch were more numerous for the forelimb, while responses to pressure and to joint movement were more numerous for the hind limb. Regardless of modalities the trunk was significantly less represented in the DSCT than the limbs. Tactile and pressure peripheral fields were restricted (i.e., a few hairs of a paw) and large (i.e., more than one segment of a limb). The ratio of restricted to large fields for touch was 7 to 1, and for pressure 5 to 1. Fibers activated by joint movements adjusted their frequency of firing to the degree of displacement and to the rate of the movement. There was no evidence for a separate anatomical segregation of fibers responding to a single sensory modality.