Cerebral cortical areas associated with the activation of climbing fibre input to cerebellar Purkinje cells
Rowe, M.J.
Archives Italiennes de Biologie 115(2): 79-93
1977
ISSN/ISBN: 0003-9829 PMID: 879958 Document Number: 115320
Purkinje cells within the anterior lober of the cerebellum were identified by stimulation of the periphery of the contralateral cerebral cortex. Over 90% of cells received activation over their climbing fiber afferents from both these sources. Each Purkinje cell was tested for climbing fiber activation from many cortical locations including the various somatic projection foci. Of the Purkinje cells, 30% displayed climbing fiber responses from only the hindlimb or forelimb division of the primary somatic projection area, SI. The remaining cells were activated from more than 1 cortical location, the site of lowest threshold was always associated with the SI area. Purkinje cells with lowest threshold for climbing fiber activation from the forelimb area of SI were all located within lobules IV and V of the cerebellum and in almost all cases were activated from the periphery by forelimb inputs. Those activated at lowest threshold from the hindlimb area of SI were all activated by the sciatic nerve and were predominantly within lobules II and III in the pars intermedia, but extended from lobule II to V in the vermis. Somatotopic organization of climbing fiber inputs from the SII and SIII cortical areas was also apparent for some cells. Discontinuities in some of the wider cortical fields from which climbing fiber responses were evoked indicated that current spread to the most effective SI site did not account for responses arising from other cortical areas. The latter responses were obtained following the removal of the pericruciate cortex suggesting that descending pathways responsible for climbing fiber activation emerge, not only from the pericruciate area but also from other regions of the somatosensory cortex.