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Projections of physiologically defined subdivisions of the inferior colliculus in the mustacbed bat: Targets in the medial geniculate body and extrathalamic nuclei
Author(s) -
Wenstrup Jeffrey J.,
Larue David T.,
Winer Jeffery A.
Publication year - 1994
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.903460204
Subject(s) - biology , inferior colliculus , medial geniculate body , superior colliculus , neuroscience , geniculate , geniculate body , anatomy , nucleus , visual cortex
This study examined the output of the central nucleus of the inferior colliculus to the medial geniculate body and other parts of the nervous system in the mustached bat ( Pteronotus parnellii ). Small deposits of anterograde tracers (horseradish peroxidase, [ 3 H]leucine, Phaseolus vulgaris leucoagglutinin, wheat germ agglutinin conjugated to horseradish peroxidase, or biocytin) were made at physiologically defined sites in the central nucleus representing major components of the bat's echolocation signal. The topography, frequency specificity, and axonal morphology of these outputs were studied. The medial geniculate body was a major target of inferior collicular neurons, with three distinct input patterns. The projection to the ventral division was tonotopically organized, but had a relatively sparse contribution from neurons representing frequency modulated components of the biosonar pulse. The second input was to the rostral medial geniculate body, in which projections from inferior collicular neurons representing constant frequency sonar components were separated from those representing frequency modulated components. A third input was to the suprageniculate nucleus, which received strong, topographically arranged projections. Inputs to the dorsal nucleus and medial division were also observed. Extrathalamic regions receiving input included the pontine gray, external nucleus of the inferior colliculus, pericollicular tegmentum, nucleus of the brachium of the inferior colliculus, and pretectum. These central nucleus projections differed in organization and the structure of axon terminals, suggesting different physiological influences on their target nuclei. These results demonstrate that the central nucleus has divergent projections to various sensory and premotor nuclei, besides its well‐established projection to the medial geniculate body. © 1994 Wiley‐Liss, Inc.