Distribution of Cutaneous Nociceptive and Tactile Climbing Fibre Input to Sagittal Zones in Cat Cerebellar Anterior Lobe.

Climbing fibres projecting to the cerebellar C3 zone (and the related C1 and Y zones) receive spatially well organized tactile and nociceptive inputs from the skin. In the present study, cutaneous tactile and nociceptive input to climbing fibres projecting to the X, B, C2 and D1 zones in lobule V were investigated in pentobarbitone-anaesthetized cats. From the present results and previous studies, it is concluded that the X, C1, CX, C3 and Y zones receive cutaneous nociceptive climbing fibre input. By contrast, climbing fibres to the B, C2 and D1 zones lack cutaneous nociceptive input. Tactile input was found in all zones. The spatial organization of receptive fields of climbing fibres projecting to the X and D1 zones was similar to that in the C3 zone. They were located on the ipsilateral forelimb, mainly its lateral and distal parts, and their proximal borders were located close to joints. In the B zone, more than half of the receptive fields of climbing fibres were confined to the ipsilateral hind- or forelimb. However, frequently more than one limb and parts of the trunk were included. In the C2 zone, the majority of climbing fibres had distal ipsi- or bilateral receptive fields on the forelimbs, often also including the head/face. Some of the bilateral forelimb receptive fields additionally included the hindlimbs ipsi- or bilaterally. The results indicate that each zone has a characteristic set of climbing fibre receptive fields, which is probably related to its efferent control functions.