Cortical organization in moles: evidence of new areas and a specialized S2

The somatosensory cortex of several mole species (family Talpidae), with di fferent peripheral sensory adaptations, was investigated and compared to de termine common and specialized features of cortical organization. Previousl y unidentified medial representations of the trunk and limbs were found in all species, indicating that S1 in moles occupies a medial to lateral strip of cortex as in most other mammals. This finding suggests a large lateral forelimb representation, previously attributed to S1, is actually part of S 2. In the face representation, evidence was found for three representations of the unusual nose of the star-nosed mole (Condylura cristata). Each of t hese areas was divided into a series of modules (visible in cytochrome oxid ase processed tissue) representing individual nasal appendages on the star. In the closely related but less specialized eastern mole (Scalopus aquatic us) and coast mole (Scapanus orarius), only two nose representations were i dentified in an area of cortex with a more uniform histological appearance. The results indicate that moles have enlarged somatosensory representation s of the glabrous nose as compared to shrews and rats that instead have lar ge vibrissal representations. In addition moles have a very large and speci alized representation of the digging forepaw in S2. Since this part of S2 p rojects directly to the cervical spinal cord, the specialization may provid e adaptive sensorimotor functions related to digging.