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Cerebellar corticonuclear and corticovestibular fibers of the flocculonodular lobe in a prosimian primate ( Galago senegalensis )
Author(s) -
Haines D. E.
Publication year - 1977
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.901740405
Subject(s) - prosimian , flocculus , galago , anatomy , biology , lobe , primate , neuroscience , cerebellum , lemur
Efferent projections from the flocculonodular lobe and the ventral part of the uvula were studied in a prosimian primate ( Galago senegalensis ) utilizing the Fink and Heimer (1967) method. Corticonuclear and corticovestibular fibers of the flocculonodular lobe and ventral uvula are ipsilateral. Fibers from both the flocculus and nodulus appear to terminate in cell group y (of Brodal and Pompeiano, 1957) although there is little evidence of other projections beyond the vestibular complex. The cortex of the flocculus sends numerous fibers into ventral portions of the NL, central areas of the SVN, and rostral and ventral regions of the MVN and fewer fibers into dorsal and medial SpVN. Many fibers from the nodulus terminate in ventrocaudal NM, peripheral areas of the SVN, and dorsal and caudal MVN. Fewer fibers course into ventral areas of the ipsilateral NL and in approximately the dorsal half of the SpVN and in its ventrolateral area at caudal levels. The LVN receives few, if any, fibers from the flocculonodular lobe. When present they appear to end almost exclusively in those areas of the LVN which border the SVN, MVN, or SpVN. The ventral uvula sends fibers mainly to the dorsomedial SVN, throughout the dorsal SpVN and in its ventrocaudal area, and to a limited region of the ventrolateral MVN at caudal levels. A few fibers from the ventral uvula distribute to dorsolateral SVN, to central areas of the caudal SpVN, and to the ventral MVN at caudal levels. Corticonuclear and corticovestibular fibers of the flocculus, nodulus and ventral uvula are (1) topographically organized with respect to their specific nuclei of termination and (2) have terminal fields in the cerebellar nuclei and vestibular complex which are partially coextensive (with the terminal field of one or both of the other lobules) and partially exclusive (to that particular lobule). Projections are seen into ventral portions of the ipsilateral NL from both floccular (hemisphere) and nodular (vermis) cortices. It is postulated that this may represent a direct route through which the flocculonodular cortex may assist in the regulation of eye movement since the primate NL, expecially its ventral part, sends fibers to certain of the contralateral oculomotor nuclei via the crossed ascending limb of the brachium conjunctivum (Carpenter and Strominger, 1964; Martin et al., 1974; Chan‐Palay et al.,1976).