title: Ventral medial nucleus neurons send thalamocortical afferents more widely and more preferentially to layer 1 than neurons of the ventral anterior-ventral lateral nuclear complex in the rat.
abstract: Not only inhibitory afferent-dominant zone (IZ) of the ventral anterior-ventral lateral thalamic complex (VA-VL) but also the ventral medial nucleus (VM) is known to receive strong inputs from the basal ganglia and send axons to motor areas. We previously reported differences in axonal arborization between IZ neurons and the other VA-VL neurons in rats by single-neuron tracing with viral vectors. In the present study, the axonal arborization of single VM neurons was visualized by the same method, and compared with that of IZ neurons. VM neurons formed fewer axon collaterals in the striatum, but sent axon fibers more widely and more preferentially (79% of fibers) to layer 1 of cortical areas than IZ neurons. Furthermore, the VM seemed to contain at least 2 types of neurons; a major population of VM neurons sent axon fibers principally to motor-associated areas as VA-VL neurons did, and the other population projected mainly to orbital or cingulate areas. Although both VM and IZ neurons receive strong basal ganglia inputs, these results suggest that VM neurons, at a single neuron level, innervate the apical dendrites of cortical pyramidal neurons more intensely and more widely than IZ neurons.
authors: Department of Morphological Brain Science, Graduate School of Medicine, Kyoto University, Kyoto 606-8501, Japan.
authors: Eriko
authors: E
authors: Kuramoto
authors: Department of Morphological Brain Science, Graduate School of Medicine, Kyoto University, Kyoto 606-8501, Japan Department of Dental Anesthesiology, Graduate School of Medicine and Dentistry, Kagoshima University, Kagoshima 890-8544, Japan.
authors: Sachi
authors: S
authors: Ohno
authors: Department of Morphological Brain Science, Graduate School of Medicine, Kyoto University, Kyoto 606-8501, Japan.
authors: Takahiro
authors: T
authors: Furuta
authors: Department of Morphological Brain Science, Graduate School of Medicine, Kyoto University, Kyoto 606-8501, Japan.
authors: Tomo
authors: T
authors: Unzai
authors: Department of Morphological Brain Science, Graduate School of Medicine, Kyoto University, Kyoto 606-8501, Japan.
authors: Yasuhiro R
authors: YR
authors: Tanaka
authors: Department of Morphological Brain Science, Graduate School of Medicine, Kyoto University, Kyoto 606-8501, Japan.
authors: Hiroyuki
authors: H
authors: Hioki
authors: Department of Morphological Brain Science, Graduate School of Medicine, Kyoto University, Kyoto 606-8501, Japan.
authors: Takeshi
authors: T
authors: Kaneko
mesh_terms: D000344:Afferent Pathways / Q000166:cytology; D000818:Animals; D001369:Axons / Q000648:ultrastructure; D002540:Cerebral Cortex / Q000166:cytology*; D003712:Dendrites / Q000648:ultrastructure; D008297:Male; D009474:Neurons / Q000166:cytology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D020651:Ventral Thalamic Nuclei / Q000166:cytology*
keywords: layer 1; motor thalamic neurons; sindbis viral vector; single-neuron tracing; ventral medial thalamic nucleus