Extracellular and intracellular recordings from cat's cortical whisker projection area: thalamocortical response transformation

Publisher Website
Google Scholar
Abstract
Transmission properties of cortical cells and of afferent thalamocortical fibers (t-c-fibers) of the whisker system in the cat were investigated under barbiturate anesthesia. After electrical stimulation of the infraorbital nerve t-c-fibers responded with latencies of 2.0-4.5 ms (cortical cells 3-8 ms) and could be driven at much higher frequencies (up to 200/s) than cortical cells (mostly up to 20-30/s). During whisker displacement, nearly 50% of the t-c-fibers showed tonic response components, in cortical cells such responses were rare and much weaker. Intracellularly strong inhibitory polarization could be demonstrated following the initial excitatory response. Cortical cells showed a limited dynamic range of responses to quantitative stimulus variations in contrast to t-c-fibers. About 50% of the latter were essentially excited from only 1 whisker, while this was the case in only 20% of the cortical cells. Multi whisker input to cortical cells was typically graded. In 1 instance, it could be shown by double recording that a cortical cell could receive its essential excitatory input from only 1 t-c-fiber.