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Laminar and cellular targets of individual thalamic reticular nucleus axons in the lateral geniculate nucleus in the prosimian primate Galago
Author(s) -
Uhlrich Daniel J.,
Manning Karen A.,
Feig Sherry L.
Publication year - 2003
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.10568
Subject(s) - parvocellular cell , galago , thalamic reticular nucleus , lateral geniculate nucleus , magnocellular cell , neuroscience , biology , reticular connective tissue , geniculate , reticular activating system , thalamus , reticular formation , anatomy , laminar organization , nucleus , visual cortex , primate
The visual sector of the thalamic reticular nucleus is the source of the primary inhibitory projection to the visual thalamic relay nucleus, the dorsal lateral geniculate nucleus. The purpose of this study was to investigate laminar and cellular targets of individual thalamic reticular nucleus axons in the highly laminated lateral geniculate nucleus of the prosimian primate Galago to better understand the nature and function of this projection. Thalamic reticular axons labeled anterogradely by means of biotinylated dextran amine were examined by using light microscopic serial reconstruction and electron microscopic analysis in combination with postembedding immunohistochemical labeling for the neurotransmitter γ‐aminobutyric acid (GABA). The synaptic targets of labeled reticular terminal profiles were primarily GABA‐negative dendrites (79–84%) of thalamocortical cells, whereas up to 16% were GABA‐positive dendritic shafts or F2 terminals of interneurons. Reconstructed thalamic reticular nucleus axons were narrowly aligned along a single axis perpendicular to the geniculate laminar plane, exhibiting a high degree of visuotopic precision. Individual reticular axons targeted multiple or all geniculate laminae, with little laminar selectivity in the distribution of swellings with regard to the eye of origin or to the parvocellular, koniocellular, or magnocellular type neurons contained in the separate layers of the Galago lateral geniculate nucleus. These results suggest that cells in the visual thalamic reticular nucleus influence the lateral geniculate nucleus retinotopically, with little regard to visual functional streams. J. Comp. Neurol. 458:128–143, 2003. © 2003 Wiley‐Liss, Inc.