PROCESSING OF SPINAL SOMATOSENSORY INFORMATION IN ANTERIOR AND POSTERIOR CEREBELLUM OF THE PIGEON

Birds have a well-developed cerebellum which serves sensorimotor contr ol of flight and other movements. In contrast to anatomical investigat ions there are only preliminary electrophysiological studies of somato sensory representation in the anterior avian cerebellum and none in th e posterior cerebellum Therefore, processing of spinal somatosensory i nformation in the cerebellum of the pigeon was studied in detail by me ans of single unit recordings from the cerebellar cortex of both anter ior and posterior cerebellum. Responses of both the mossy fibre system and of the climbing fibre system were studied utilizing both electric al stimulation of peripheral nerves and natural cutaneous and deep (pr oprioceptive) stimuli. Response latencies point to a direct input from spinal pathways in most cases. As in mammalian species there was a se parate representation of the body both in anterior and posterior cereb ellum. Although there was a large overlap of the representation of var ious parts of the body, wings and legs dominated in different lobules. Whereas proprioceptive input was dominant in anterior cerebellum (lob ules II-VI) posterior cerebellum (lobule IX) seems to process predomin antly cutaneous input.