Organization of climbing fibre projections to the cerebellar cortex from trigeminal cutaneous afferents and from the SI face area of the cerebral cortex in the cat.

Abstract

SUMMARY1. In cats anaesthetized with pentobarbitone, the projection of climbing fibres (CFs) to the cerebellar cortex from trigeminal cutaneous branches and from the face area of the sensorimotor (SI) cortex was mapped, using the technique of laminar field potential analysis.2. The CF projections from both the trigeminal nerve and the SI face area were found to be localized to the same cerebellar folia, viz. chiefly the ipsilateral lobule HVI, with a small overlap on to the adjacent folia of lobule V and crus Ia of HVIIA. Frequently a projection from the superficial radial nerve to part or all of this area, was also found.3. A correspondence in the distribution and amplitudes of CF potentials evoked at most points by stimulation of the trigeminal nerve and the SI cortex was found. This implies a convergence of afferents from these two sources at or before the inferior olive.4. In more than half of the cats, a small area of the cerebellar hemisphere was found, in which contralateral as well as ipsilateral trigeminal stimulation would evoke CF potentials. Usually inputs from the superficial radial nerve and the SI cortex also converged upon this area.5. The organization of CF projections from trigeminal and superficial radial nerve afferents to the cerebellar hemisphere was found to occur in the same 'patchy' pattern of somatotopy that has been described for spinal nerve inputs to the anterior lobe.6. One constant factor was found in the pattern of organization of CF projections to this area from cutaneous afferent nerves. That is, only the afferents from overlapping areas of skin projected to a given recording point: no instance of CF projections from trigeminal branches innervating discontinuous skin areas was observed.

Climbing fibre inputs to cerebellar Purkinje cells from trigeminal cutaneous afferents and the SI face area of the cerebral cortex in the cat.

“…The area of the cerebellum to which trigeminally excited CFs project is described in the preceding paper viz. the Purkinje cell layer of lobule HVI (Larsell, 1953), and of the adjoining folia of lobule V and crus Ia of lobule HVIIA (Miles & Wiesendanger, 1975 Forty-four cells (33 %) responded to electrical stimulation of one ipsilateral branch, sixty-two cells (47 %) to two branches, and twenty-six cells (20 %) to all three. Of the forty-four cells which responded to only one trigeminal branch, seventeen were activated by the infraorbital nerve.…”

“…Much of the data presented in this report was obtained during the course of the preceding field potential investigation (Miles & Wiesendanger, 1975). Hence the general experimental procedures have been described in detail.…”

“…4. The effectiveness of the pulpul stimulus varies from a powerful Convergence from superficial radial nerve The preceding field potential study demonstrated the existence of a partial overlap of the CF projections from forelimb and trigeminal nerves (Miles & Wiesendanger, 1975). Accordingly, 117 cells in which a CF response was evoked by trigeminal stimulation, were tested for an input from the superficial radial nerve, and convergence was found on twentyseven of these cells (Figs.…”

“…Amongst these are the exceptionally high density of innervation of the face area (Darian-Smith, Mutton & Proctor, 1965), which is reflected in the large representation of the face in the sensory cortex (Darian-Smith, Ibister, Mok & Yokota, 1966); the unique sensory properties of the vibrissae (Zucker & Welcker, 1969;Pubols, Donovick & Pubols, 1973) and the dental pulp (Brookhart, Livingston & Haugen, 1953;Anderson, Hannam & Matthews, 1970); and the unique anatomical and physiological properties of the trigeminal sensory nuclei in the brainstem and spinal cord (Olzewski, 1950;Wall & Taub, 1962). In the preceding study, the general localization and overall pattern of CF projection from trigeminal cutaneous afferents and the SI cortex was described, using electrical stimulation of nerve trunks and laminar field potential analysis (Miles & Wiesendanger, 1975). The findings of that study are confirmed and extended in the present investigation, by recording CF responses of single Purkinje cells, using electrical and natural stimulation of the face and forelimb, as well as electrical stimulation of the SI face area of the cerebral cortex.…”

Responses in the posterior lobe of the rat cerebellum to electrical stimulation of cutaneous afferents to the snout.

“…However we neither confirmed nor excluded the existence of bilateral convergence onto individual climbing fibres in the hemisphere. In the cat, however, some Purkinje cells in the hemisphere are supplied by climbing fibres which can be driven from both sides of the face (Miles & Wiesendanger, 1975a).…”