Representations of the body surface by climbing fiber responses in the dorsal paraflocculus of the cat.

Mechanical stimulation elicited climbing fiber responses in 22% of the 377 Purkinje cells isolated in the dorsal paraflocculus of cats anesthetized with sodium pentobarbital. The responsive units were not evenly distributed throughout the dorsal paraflocculus. In the posterior division, 37% (65/177) of the cells had climbing fiber responses elicited by tactile stimulation, whereas in the lateral and accessory divisions the units were mainly unresponsive to tactile stimulation. Eleven of the 174 cells were responsive to tactile stimulation in the lateral division and only one climbing fiber response was driven in the 26 cells isolated in the accessory division. The climbing fiber representation was mainly of the ipsilateral forelimb and hindlimb with only a few responses representing the face. About half of the hindlimb representation was encountered in a patch located in the most medial part of the posterior division. No consistent location was identified between animals for the rest of the representations, which were intermingled among unresponsive units. The receptive fields of the majority of the forepaw and hindpaw representation included areas of the lateral toes; only a few responses represented the medial parts of the paw.

Widening of inter-Purkinje cell distances in association with corpora amylacea.

Inter-Purkinje cell distances were determined in random routine cerebellums obtained at autopsies of adults over the age of 50. There was a significant increase in the inter-Purkinje cell distances proportionate to the increase in adjacent corpora amylacea. The possibility of replacement of Purkinje cells by corpora amylacea is discussed.

A topographic analysis of limbic and somatic inputs to the cerebellar cortex in the rat.

The effects of electrical stimulation of the fornix, snout, and limbs on the activity of electrophysiologically identified Purkinje cells were investigated. Extracellularly recorded responses were analyzed according to: latency; mode of termination as mossy or climbing fibers; and, whether excitatory or inhibitory responses were evoked. The positions of responsive cells were transposed onto a planar representation of the Purkinje cell layer of the rat cerebellum derived from a series of sagittal sections. Fornix responsive cells were found in the vermis of lobules IV, V, VI, and VII as well as in the paravermal regions of lobules II--VIIb. In addition, some evidence was obtained for a projection to lobulus simplex. Snout stimulation activated cells mainly in the vermis of lobule VI and also in adjacent lobules III, IV, V, and VIIa. A few responsive cells were also found in the paravermal regions of lobules V, VI, and VIIa and in the lateral portion of lobulus simplex. Forelimb responsive cells were located mainly in the vermis of lobules IV--VIa and in the paravermal protion of lobules III--VII. The few hindlimb cells encountered were located in the vermis and paravermis of lobules II--IV. The topographical overlap of the fornix projection with areas in receipt of forelimb, snout, neck, and auditory-visual teleceptor input suggests that the fornix-mediated information may modulate cerebellar circuits involved in postural adjustment, general orienting, and exploratory motor behavior.