C‐FOS expression in the visual system of tree shrews after monocular inactivation. Issue 1 (19th June 2016)

• Record Type: Journal Article
• Authors: Takahata, Toru; Kaas, Jon H.
• Is Part Of: Journal of comparative neurology. Volume 525:Issue 1(2017)
• Page Start: 151
• Page End: 165
• Publication Date: 2016-06-19
• Subjects: ZIF268 -- tetrodotoxin -- ocular dominance -- in situ hybridization -- Tupaia -- striate cortex; Comparative neurobiology -- Periodicals; Neurology -- Periodicals; 616
• DOI: 10.1002/cne.24053
• Languages: English
• ISSNs: 0021-9967

Abstract

ABSTRACT: Tree shrews possess an unusual segregation of ocular inputs to sublayers rather than columns in the primary visual cortex (V1). In this study, the lateral geniculate nucleus (LGN), superior colliculus (SC), pulvinar, and V1 were examined for changes in c‐FOS, an immediate‐early gene, expression after 1 or 24 hours of monocular inactivation with tetrodotoxin (TTX) in tree shrews. Monocular inactivation greatly reduced gene expression in LGN layers related to the blocked eye, whereas normally high to moderate levels were maintained in the layers that receive inputs from the intact eye. The SC and caudal pulvinar contralateral to the blocked eye had greatly (SC) or moderately (pulvinar) reduced gene expressions reflective of dependence on the contralateral eye. c‐FOS expression in V1 was greatly reduced contralateral to the blocked eye, with most of the expression that remained in upper layer 4a and lower 4b and lower layer 6 regions. In contrast, much of V1 contralateral to the active eye showed normal levels of c‐FOS expression, including the inner parts of sublayers 4a and 4b and layers 2, 3, and 6. In some cases, upper layer 4a and lower 4b showed a reduction of gene expression. Layers 5 and sublayer 3c had normally low levels of gene expression. The results reveal the functional dominance of the contralateral eye in activating the SC, pulvinar, and V1, and the results from V1 suggest that the sublaminar organization of layer 4 is more complex than previously realized. J. Comp. Neurol. 525:151–165, 2017. © 2016 Wiley Periodicals, Inc. Abstract : Tree shrews have a unique organization of the visual system compared with other species. The expression of c‐FOS, an immediate‐early gene, reveals laminar arrangement of ocular dominance of tree shrews, which is mostly consistent with previous studies but also suggests more complex sublaminae in the primary visual cortex.