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Retrograde analyses of spinothalamic projections in the macaque monkey: Input to posterolateral thalamus
Author(s) -
Craig A.D. Bud,
Zhang EnTan
Publication year - 2006
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.21155
Subject(s) - spinothalamic tract , thalamus , anterograde tracing , neuroscience , retrograde tracing , macaque , lamina , anatomy , biology , spinal cord , lumbosacral joint , axoplasmic transport , zona incerta , central nervous system , nociception , biochemistry , receptor
The distribution of retrogradely labeled spinothalamic tract (STT) neurons was analyzed in macaque monkeys following variously sized, physiologically guided pressure or iontophoretic injections of cholera toxin subunit B (CTb) in order to determine whether different STT termination sites receive input selectively from different sets of STT cells. This report focuses on posterolateral thalamus, where prior anterograde tracing observations identified the posterior part of the ventromedial nucleus (VMpo) as the major projection target of lamina I STT neurons. Large injections in posterolateral thalamus labeled predominantly STT cells in lamina I throughout the spinal cord. In cases with medium‐sized or small injections centered in VMpo, almost all labeled STT cells (∼90%) were lamina I neurons. Small injections revealed a posteroanterior (foot to hand) somatotopographic organization consistent with that observed in prior anterograde tracing work; injections in posterior VMpo labeled primarily lumbosacral lamina I cells, whereas injections placed more anteriorly in VMpo labeled primarily cervical lamina I cells. These findings support the concept that VMpo is a primate lamina I spinothalamocortical relay nucleus important for pain, temperature, itch, muscle ache, sensual touch, and other interoceptive feelings from the body, and they provide strong evidence for the general hypothesis that the STT consists of several functionally and anatomically differentiable components. J. Comp. Neurol. 499:953–964, 2006. © 2006 Wiley‐Liss, Inc.