Projections from cortical area SmII and claustrum to two functional subdivisions of SmI forepaw digit cortex of the raccoon.
The retrograde HRP tracer method was used to study the projections from cortical area SmII and the claustrum to two electrophysiologically defined, functionally distinct subdivisions of the SmI forepaw cortex of the raccoon. Individual SmI cortical digit zones were found to receive ipsilateral projections from SmII and immediately adjoining cortical regions; the projections to the "heterogeneous" (hairy skin and claw) functional subdivision of a given digit zone were considerably more extensive than those to the glabrous skin functional subdivision of that zone. HRP-filled neurons within SmII were located primarily in layers VI and V, often formed clusters, and were distributed antero-posteriorly in a manner consistent with a loosely topographic representation of the digits. The SmI cortical digit zones received ipsilateral projections from approximately the middle 1/3 of the anterior-posterior extent of the insular claustrum; no clear difference was found in the projections to the two functional subdivisions of a given digit zone. Labeled neurons were typically scattered throughout much of the claustrum but were more numerous in its dorsal regions, tended to aggregate in clusters, and were distributed antero-posteriorly in an overlapping but roughly topographic fashion.
Standage
G P
GP
Department of Anatomy, Medical College of Georgia, Augusta 30912.
Doetsch
G S
GS
D000818:Animals; D001479:Basal Ganglia / Q000166:cytology*; D009434:Neural Pathways / Q000166:cytology; D009474:Neurons / Q000166:cytology; D011821:Raccoons; D013003:Somatosensory Cortex / Q000166:cytology*