Localization of the Cells of Origin of the Ventral Spino-Cerebellar Tract

Abstract

THE location of the cells of origin of the ventral spino-cerebellar tract has never been determined conclusively by anatomical investigations¹. We have now systematically searched for these cells in the lumbar segments of the cat spinal cord. Cells were identified as ventral spino-cerebellar tract neurones if they were monosynaptically excited by Golgi tendon organ (Ib) afferents and antidromically activated on stimulation of fibres in the dissected spinal half (at Th 13 or L1), contralateral to the nerve supplying Ib excitation². The position of cells encountered was derived from the co-ordinates shown by the stereotactic instrument used for insertion of the microelectrode, and histologically controlled. Fig. 1 shows the position of the 39 ventral spino-cerebellar tract neurones (five experiments) from which successful intra-cellular recordings were obtained. All these cells were activated from ipsilateral nerves and antidromically invaded from the contralateral side. Almost all units activated from the hamstring nerve were found in the upper part of the L ₅ or lower part of the L ₄ segment.