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The tectopontine projection in the cat: An experimental anatomical study with comments on pathways for teleceptive impulses to the cerebellum
Author(s) -
Kawamura Koki,
Brodal Alf
Publication year - 1973
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/cne.901490306
Subject(s) - superior colliculus , pontine nuclei , pons , neuroscience , inferior colliculus , cerebellum , biology , anatomy , paramedian pontine reticular formation , nucleus , visual system , reticular formation , midbrain , visual cortex , central nervous system
Following lesions of different sizes and locations of the superior colliculus the distribution of degenerating fibers in the pontine nuclei was determined in the cat in Nauta and Fink and Heimer impregnated sections. The superior colliculus projects exclusively to most of the dorsolateral nucleus in the ipsilateral pontine nuclei. There appears to be some degree of topical arrangement in the projection. Three cases with lesions of the superior colliculus on one side and of the inferior colliculus, the cerebral auditory or cerebral visual areas, respectively, on the other side, permit comparisons between the projections of the superior colliculus with those from the other structures mentioned. The inferior colliculus projects onto the dorsolateral nucleus of the pons in an area which overlaps to some extent with that of the superior colliculus. Confirming more systematic studies of P. Brodal it is found that the pontine projection area of the auditory cortex to a large extent coincides with that of the superior colliculus, while the pontine projection area of the visual cortex is entirely different. These findings, together with other data from the literature, strongly suggest that the pathway for optic impulses to the vermal visual area of the cerebellum passes via the superior colliculus and the dorsolateral pontine nucleus. Direct tectocerebellar fibers or pathways via the reticular formation are scarcely involved in this process. Anatomically there is evidence for another route for visual impulses to the cerebellum: via the visual cerebral cortex and the pons to regions in the cerebellar hemisphere. This is in agreement with physiological findings and suggests that there may be at least two visual areas in the cerebellum. The anatomical data show that there are ample possibilities for an integration of optic, acoustic and other impulses in the superior colliculus as well as in its projection area in the pons.