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Pallidal and cerebellar afferents to pre‐supplementary motor area thalamocortical neurons in the owl monkey: A multiple labeling study
Author(s) -
Sakai Sharleen T.,
Stepniewska Iwona,
Qi Hui Xin,
Kaas Jon H.
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/(sici)1096-9861(20000207)417:2<164::aid-cne3>3.0.co;2-6
Subject(s) - biotinylated dextran amine , globus pallidus , deep cerebellar nuclei , wheat germ agglutinin , neuroscience , cerebellum , anatomy , cytoarchitecture , ventral pallidum , biology , parvocellular cell , anterograde tracing , cuneate nucleus , nucleus , cerebellar cortex , central nervous system , basal ganglia , biochemistry , lectin
In the present study, we determined where thalamic neurons projecting to the pre‐supplementary motor area (pre‐SMA) are located relative to pallidothalamic and cerebellothalamic inputs and nuclear boundaries. We employed a triple‐labeling technique in the same owl monkey ( Aotus trivirgatus ). The cerebellothalamic projections were labeled with injections of wheat germ agglutinin conjugated to horseradish peroxidase, and the pallidothalamic projections were labeled with biotinylated dextran amine. The pre‐SMA was identified by location and movement patterns evoked by intracortical microstimulation and injected with the retrograde tracer cholera toxin subunit B. Brain sections were processed sequentially using different chromogens to visualize all three tracers in the same section. Alternate sections were processed for Nissl cytoarchitecture or acetylcholinesterase chemoarchitecture for nuclear boundaries. The cerebellar nuclei primarily projected to posterior (VLp), medial (VLx), and dorsal (VLd) divisions of the ventral lateral nucleus; the pallidum largely projected to the anterior division (VLa) of the ventral lateral nucleus and the parvocellular part of the ventral anterior nucleus (VApc). However, we also found zones of overlapping projections, as well as interdigitating foci of pallidal and cerebellar label, particularly in border regions of the VLa and VApc. Thalamic neurons labeled by pre‐SMA injections occupied a wide band and were especially concentrated in the VLx and VApc, cerebellar and pallidal territories, respectively. Labeled thalamocortical neurons overlapped cerebellar inputs in the VLd and VApc and overlapped pallidal inputs in the VLa and the ventral medial nucleus. The results demonstrate that inputs from both the cerebellum and globus pallidus are relayed to the pre‐SMA. J. Comp. Neurol. 417:164–180, 2000. ©2000 Wiley‐Liss, Inc.