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Study of projections from the entopeduncular nucleus to the thalamus of the rat
Author(s) -
Kha Hoa Ton,
Finkelstein David Isaac,
Pow David Vaughan,
Lawrence Andrew John,
Horne Malcom Kenneth
Publication year - 2000
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 - 10.1002/1096-9861(20001023)426:3<366::aid-cne2>3.0.co;2-b
Subject(s) - thalamus , habenula , neuroscience , basal ganglia , pedunculopontine nucleus , basal forebrain , biology , anatomy , cholinergic , central nervous system , medicine , parkinson's disease , deep brain stimulation , disease
The entopeduncular nucleus (EP) is a major outflow nucleus of the basal ganglia and innervates the lateral habenula, parafascicular, pedunculopontine, ventrolateral (VL), ventromedial (VM), and mediodorsal thalamic nuclei. This study investigated the morphology of single axons of entopeduncular neurons projecting to the motor thalamus by placing small injections of dextran biotin into the EP and reconstructing drawings of single axons from serial sections. There were two populations of entopeduncular‐thalamic projection axons: those that projected only to the motor thalamus (VL and VM) and those that projected to both the motor thalamus and other nuclei (e.g., the habenula). The neurochemistry of EP neurons projecting to the thalamus was investigated by injecting the retrograde tracer FluoroGold into the VL and VM thalamic nuclei to retrogradely fill entopeduncular projection neurons. These were subsequently immunohistochemically labeled for choline acetyl transferase, γ‐aminobutyric acid (GABA), and glutamate. Consistent with previous studies, significant proportions of these neurons were GABA immunoreactive. In addition, approximately half of the entopeduncular‐thalamic projecting neurons were found to be cholinergic. This excitatory input is most likely derived from axons that branch as they pass through the motor thalamus to the lateral habenula. J. Comp. Neurol. 426:366–377, 2000. © 2000 Wiley‐Liss, Inc.