THERMAL IMAGES OF SOMATIC SENSORY CORTEX OBTAINED THROUGH THE SKULL OF RAT AND GERBIL

Infrared images of the skull surface were obtained in urethane-anesthe tized rats and gerbils before, during and after mechanical stimulation of the face and mystacial vibrissae on one side. Areas of increased t emperature on the skull, localized mainly over the face area of the pr imary somatosensory cortex contralateral to the side of stimulation, a ppeared within 4-5 s after the onset of stimulation. Rarely, such temp erature change was recorded bilaterally. Temperatures did not remain h igh on the intact skull in rats, but fell to baseline within minutes a fter stimulus onset regardless of stimulus duration. In rats in which the skull had been thinned and in gerbils with intact skull, temperatu res remained elevated during the course of stimulation. We were unable to resolve the activation of individual vibrissae.