DISTURBANCES IN THE PERFORMANCE OF THERMAL DISCRIMINATION TASKS FOLLOWING CORTICAL ABLATIONS IN RATS

Previous studies of the effects of ablating the rat's somatosensory co rtex on temperature discrimination have yielded negative results. Pres ently, it was assumed that (1) the rat's face might possess thermal ac uity comparable to that found in highly sensitive skin regions of prim ates, (2) the rat's facial discriminative capacity for thermal differe nces might be more acute in a cool range well below normal room temper ature (24-degrees-C), and (3) by using more sensitive procedures and f ocusing on the effects of damage to the face areas in the rat's somato sensory cortex, disturbances in the capacity to make discriminations b etween cool stimuli might be revealed that previously went unnoticed. Results of experiments testing these assumptions indicated that rats c an use their snouts to make discriminations of 1-degrees-C or less, th at their acuity is better in the cool than in the warm range, and that somatosensory ablations produce moderate to severe disturbances in th e capacity to discriminate between cool stimuli but only slight transi tory disturbances in this capacity for warm stimuli. Additionally, the results suggest that the sensorimotor cortex may be involved in the r at's thermal discriminative capacity.