Convergence of skin and hypothalamic temperature signals on the sulcal prefrontal cortex in the rat.

Single unit activities in the sulcal prefrontal cortex (S-PEC) were recorded during thermal stimulation of scrotal skin and the hypothalamus in urethane-anesthetized rats. (1) Of all the 146 S-PFC units tested, 126 (86%) units changed the firing rate in response to changes in scrotal skin temperature (Tsc), and 98 (67%) units to alterations in hypothalamic temperature (Thyp). Sixty-five percent of the S-PFC units responded to both Tsc and Thyp changes. (2) Response characteristics of Tsc-responding S-PFC units were modified when the hypothalamus was warmed or cooled. (3) Microinjection of procaine into the dorsomedial nucleus of the thalamus reversibly blocked the response of S-PFC units to changes in Tsc and/or Thyp. (4) The high degree of convergence of thermal signals from scrotal skin and the hypothalamus on the S-PFC suggests that the S-PFC neurons play a role in processing and integrating thermal signals arising from different parts of the body, probably in connection with the emotional and/or motivational aspect of neural sensation and thermoregulatory behavior.