The corticopontine projection in the cat. II. The projection from the orbital gyrus

Abstract

Following large and small lesions of the orbital gyrus in adult cats the ensuing degeneration in the pontine nuclei was studied with the silver impregnation methods of Nauta and of Fink and Heimer. Lesions were produced by transdural thermocoagulation. The main results are as follows :All parts of the orbital gyrus give off fibers to the pontine nuclei. The density of projection is less than from the anterior ectosylvian gyrus (second somatosensory area).The orbital gyrus projects upon four longitudinal columns within the pontine nuclei. One is located medially, one ventromedially, one ventrolaterally and one dorsolaterally.The exact localization of these columns has been compared with the localization of the columns projected upon by the anterior ectosylvian gyrus. Three of the columns (the medial, ventrolateral and dorsolateral) appear to be projected upon by both gyri, while the fourth one receives afferents from the orbital gyms only.A topical localization exists within the projection from the orbital gyms insofar as the anterior part of the gyrus projects onto the medial, ventrolateral and dorsolateral columns, while the posterior part projects onto the ventromedial column mainly.Whether a somatotopical localization is present within the projection to some or all of the columns can not be decided from the material. 1. 2. 3. 4.This paper is the fourth in a series which deals with the pontine projection from different parts of the cerebral cortex in the cat. It has been possible to demonstrate a precise organization within this projection from the primary sensorimotor (P. Brodal, '68a) and second somatosensory cortex (P. Brodal, '68b). Each region projects i n a somatotopical fashion upon several longitudinally oriented, differently situated cell columns in the pontine nuclei. In view of these findings it was deemed of interest to study in the same detailed manner the pontine projection from other cortical regions. In a preceding paper (P. Brodal, '71) it was shown that the proreate gyrus projects onto the same pontine areas as does the motor cortex. The present study deals with the projection from the orbital gyrus.Of the three most important brain stem nuclei relaying impulses from the cerebral cortex to the cerebellum (the pontine nuclei, the lateral reticular nucleus and the J. COMP. NEUR., 142: 141-152.inferior olive), in the cat only the pontine nuclei have been shown to receive fibers from the orbital gyrus (Mizuno, Sauerland and Clemente, '68). However, information of the sites of termination is not given by Mizuno et al. Other authors studying projections from the orbital gyrus to subcortical regions in the cat (Hirata, '65; Valverde, '65) do not mention efferent fibers to the pontine nuclei.Jansen ('57) studying the evoked potentials in the cerebellar hemisphere following electrical stimulation of the cerebral cortex of the cat, found that stimulation of the anterior part of the orbital gyrus evoked long and short latency potentials in the dorsal paraflocculus, crus I and 11, and the anterio...

Impact of cerebellar atrophy on cortical gray matter and cerebellar peduncles as assessed by voxel-based morphometry and high angular resolution diffusion imaging

“…Similarly, the significantly smaller GM volume in Broca's area also corroborates suggestions that the cerebellum is involved in memory retrieval and language (Silveri et al, 1998;Murdoch, 2010). Finally, as for the orbitofrontal cortex, this region has been shown in animal studies to be connected to the cerebellum through corticopontine fibers (Brodal, 1971) while in humans it has been related to cerebellar activity in various diseases and conditions (e.g. Fumal et al, 2006;Frodl et al, 2010).…”

Unique Features of the Human Brainstem and Cerebellum

“…The expansion of the cerebral cortex and the cerebellum are functionally linked: the cerebellum and the cerebral cortex are highly interconnected. As shown in many studies, the cerebellum receives topographically organized input from many functional regions of the cerebral cortex via relays in the pontine nuclei (Kuypers and Lawrence, 1967; Brodal, 1968a,b, 1971a,b, 1978; Gibson et al, 1978; Glickstein et al, 1980, 1985, 1990, 1994; Cohen et al, 1981; Baker et al, 1983; Bjaalie and Brodal, 1983; Thangnipon et al, 1983; Leergaard et al, 2006; Suzuki et al, 2012). Cortical input can also influence other pre-cerebellar nuclei (references and discussion in Kuypers and Lawrence, 1967; Suzuki et al, 2012).…”