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Brain Research, 631 (1993) 241-246 241 1993 Elsevier Science Publishers B.V. All rights reserved 0006-8993/93/$06.00

Summary: Brain Research, 631 (1993) 241-246 241
1993 Elsevier Science Publishers B.V. All rights reserved 0006-8993/93/$06.00
BRES 19525
Spinothalamocortical projections to the secondary somatosensory cortex
(SII) in squirrel monkey
Richard T. Stevens *, Susan M. London, A. Vania Apkarian
Department of Neurosurgery, Neurosurgery Research Center, Weiskotten Hall, Rm 3118, SUNY Health Science Center, Syracuse, NY 1321O, USA
(Accepted 27 July 1993)
Key words: Thalamocortical; Spinal cord; Ascending projection; Nociceptive; Pain
Anterograde labeling of the cervical spinothalamic tract was combined with retrograde labeling of thalamocortical cells projecting to the hand
region of the second somatosensory cortex (hSII) to identify likely sites in the thalamus for processing and transmitting nociceptive information
to hSII. Anterograde labeling of terminals was done with 2% WGA-HRP injections in the cervical enlargement; thalamocortical cells were
retrogradely labeled with fluorescent tracers. In one experiment, the contralateral primary somatosensory cortex hand region (hSI) was injected
to provide a direct comparison with hSII thalamic label. Both labeled cells and terminal-likestructures were visualized in single thalamic sections
and their numbers and positions quantitatively analyzed. The number of labeled cells within 100 microns from the STT terminals were counted
as overlapping cells. Four thalamic nuclei, ventroposterior inferior (VPI), ventroposterior lateral (VPL), posterior nucleus (PO) and centrolateral
nucleus (CL) combined to contain 86.5% of all hSII-projectingoverlapping cells. Of all hSII-projectingthalamic overlapping cells, VPI contained
the largest number (36.4% of the total) followed by the anterior portion of the posterior nuclear complex (POa; 20.4%), VPL (18.3%) and CL
(11.4%). Results of the hSI injection show a different pattern of overlap in agreement with our earlier study. The relative distribution of
overlapping cells was dependent on the antero-posterior position of the SII injections. The most anterior injections resulted in small numbers of


Source: Apkarian, A. Vania - Department of Physiology, Northwestern University


Collections: Biology and Medicine