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Somatosensory Nuclei of the Manatee Brainstem and Thalamus
Author(s) -
Sarko Diana K.,
Johnson John I.,
Switzer Robert C.,
Welker Wally I.,
Reep Roger L.
Publication year - 2007
Publication title -
the anatomical record: advances in integrative anatomy and evolutionary biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.678
H-Index - 62
eISSN - 1932-8494
pISSN - 1932-8486
DOI - 10.1002/ar.20573
Subject(s) - thalamus , somatosensory system , neuroscience , brainstem , anatomy , biology , cuneate nucleus , nucleus
Florida manatees have an extensive, well‐developed system of vibrissae distributed over their entire bodies and especially concentrated on the face. Although behavioral and anatomical assessments support the manatee's reliance on somatosensation, a systematic analysis of the manatee thalamus and brainstem areas dedicated to tactile input has never been completed. Using histochemical and histological techniques (including stains for myelin, Nissl, cytochrome oxidase, and acetylcholinesterase), we characterized the relative size, extent, and specializations of somatosensory regions of the brainstem and thalamus. The principal somatosensory regions of the brainstem (trigeminal, cuneate, gracile, and Bischoff's nucleus) and the thalamus (ventroposterior nucleus) were disproportionately large relative to nuclei dedicated to other sensory modalities, providing neuroanatomical evidence that supports the manatee's reliance on somatosensation. In fact, areas of the thalamus related to somatosensation (the ventroposterior and posterior nuclei) and audition (the medial geniculate nucleus) appeared to displace the lateral geniculate nucleus dedicated to the subordinate visual modality. Furthermore, it is noteworthy that, although the manatee cortex contains Rindenkerne (barrel‐like cortical nuclei located in layer VI), no corresponding cell clusters were located in the brainstem (“barrelettes”) or thalamus (“barreloids”). Anat Rec, 290:1138–1165, 2007. © 2007 Wiley‐Liss, Inc.