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Geometry of rubrospinal, rubroolivary, and local circuit neurons in the macaque red nucleus
Author(s) -
Burman Kathleen,
DarianSmith Corinna,
DarianSmith Ian
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(20000724)423:2<197::aid-cne2>3.0.co;2-0
Subject(s) - parvocellular cell , red nucleus , neuroscience , soma , biology , dendrite (mathematics) , neuron , anatomy , spinal cord , nucleus , biocytin , lucifer yellow , retrograde tracing , central nervous system , microbiology and biotechnology , intracellular , geometry , mathematics , gap junction
The primate red nucleus consists of three main neuron subpopulations, namely, rubrospinal neurons in the magnocellular nucleus, rubroolivary cells in the parvocellular nucleus, and local circuit neurons in both subnuclei: Each subpopulation has unique cerebellar and neocortical inputs. The structural framework for the interactions of these rubral subpopulations remains poorly defined and was the focus of this study in six macaques. Somata of rubrospinal neurons, dorsolateral‐spinal (DL‐spinal) neurons, as defined in the accompanying paper (Burman et al. [2000] J. Comp. Neurol., this issue), and rubroolivary neurons were labeled retrogradely first with Fast Blue injected either into the cervical spinal cord or the inferior olive. The soma/dendrite profiles of selected cells (53 rubrospinal, 19 DL‐spinal, and 17 rubroolivary cells) were visualized by the intracellular injection of Lucifer Yellow/biocytin in fixed slices (400 μm thick) of midbrain. The descriptive statistics of the somata and the dendritic arborization of each rubral neuron type were established. Projection neuron subpopulations had similar but differentiable soma/dendrite profiles, with four to six slender, spine‐bearing dendritic trees radiating out ≈400 μm from the soma. Twelve presumed interneurons, all in the parvocellular nucleus, differed from projection neurons in that they had smaller somata and many slender, spine‐bearing segments that constituted the multibranching dendrite profile that radiated out ≈250 μm from the soma. A tentative model of the macaque rubral microcircuitry was developed, and its functional implications were explored. It incorporated 1) the known topography of the nucleus and its connections, 2) our data specifying the soma/dendrite morphology of the three main rubral neuron types, and 3) the ultrastructure reported by other laboratories of intrarubral synaptic connections. J. Comp. Neurol. 423:197–219, 2000. © 2000 Wiley‐Liss, Inc.