Differential origins of spinothalamic tract projections to medial and lateral thalamus in the rat.

摘要: In an earlier study (Giesler et al., 1976), antidromically identified cells of origin the rat spinothalamic tract (STT) were found to be widely distributed throughout lumbar dorsal horn and intermediate gray zone (IGZ). Interestingly, it appeared that STT neurons located within ventral IGZ, which respond stimuli delivered subcutaneous tissue, tended activated only from midline thalamic structures. contrast, nucleus proprius marginal zone, responded noxious innocuous cutaneous stimuli, lateral The present has investigated this apparent dichotomy in afferents using technique retrograde transport horseradish peroxidase (HRP). Single multiple small injections HRP made various regions. Tissue was reacted with diaminobenzidine (DAB) or o-dianisidine (OD). Our data provide evidence DAB histochemistry yields a more accurate reflection concentrations surrounding injection site are necessary for visible transport. On other hand, OD useful examining labeled spinal cord neurons. With method, 3 5.3 times seen far greater morphological detail evident. Multiple infusions filled entire hemi-thalamus large numbers extensions column nuclei, cervical nucleus, horns IGZ bilaterally C1 C2, at all levels. also seen, but lesser zone. Labeling segments below C3 was, single exception, exclusively contralateral. enlargement contribute number than enlargement. Injections into posterior medial structures produced bilateral labeling upper segments. Within enlargements, restricted contralaterally. exception C2 where marked reduction occurred, anterior identical areas matter comparable those by injections. yielded dense caudal nuclei nucleus. Labeled levels. Together our findings, these suggest is composed two components vary their origin, terminations and, very likely, functions.