Organization of the forepaw representation in ferret somatosensory cortex.

Little is known about the function and structure of ferret somatosensory cortex. We used anatomical methods and multi-unit recordings to characterize the cytoarchitecture, functional responses and topography of the forepaw representation in ferret somatosensory cortex. The representation of the cutaneous ferret forepaw encompasses approximately the caudal half of the posterior sigmoid gyrus. The posterior sigmoid gyrus and coronal sulcus contain unique cytoarchitectonic fields that conform in large part to earlier descriptions of somatosensory regions in the cat. The cytoarchitectonic regions form mediolateral bands that comprise areas 4, 3a, 3b, 1, and 2 (from rostral to caudal). We studied most extensively areas 3a and 3b for functional responses to somatic stimuli; our data indicate that ferret somatosensory cortex contains at least two representations of the forepaw in these two areas. Our data also suggest that within ferret somatosensory cortex, the morphological and submodality features gradually, rather than abruptly, distinguish themselves as unique cortical fields.