Thalamocortical Radiations - Somatosensory Areas

Somatosensory Areas

Primarily, thalamocortical somatosensory radiation from the VPL VPM and LP nuclei extends to the primary and secondary somatosensory areas, terminating in cortical layers of the lateral postcentral gyrus. S1 receives parallel thalamocortical radiations from the posterior medial nucleus and the VPN. Projections from the VPN to the postcentral gyrus account for the transfer of sensory information concerning touch and pain. Several studies indicate that parallel innervations to S1 and also S2 via thalamocortical pathways result in the processing of nociceptive and non-nociceptive information. Non-specific projections to sensori-motor areas of the cortex may in part have to do with the relationship between non-noci-receptive processing and motor functions. Past research shows a link between S1 and M1, creating a thalamocortical sensori-motor circuit. When this circuit becomes disrupted symptoms are produced similar to those that accompany Multiple sclerosis, suggesting thalamocortical rhythms are involved in regulating sensori-motor pathways in a highly-specialized manner. TC-CT rhythms evident during sleep act to inhibit these thalamocortical fibers so as to maintain the tonic cycling of low frequency waves and the subsequent suppression of motor activity.