Disturbances in the performance of thermal discrimination tasks following cortical ablations in rats

Previous studies of the effects of ablating the rat's somatosensory cortex on temperature discrimination have yielded negative results. Presently, it was assumed that (1) the rat's face might possess thermal acuity comparable to that found in highly sensitive skin regions of primates, (2) the rat's facial discriminative capacity for thermal differences might be more acute in a cool range well below normal room temperature (24 degrees C), and (3) by using more sensitive procedures and focusing on the effects of damage to the face areas in the rat's somatosensory cortex, disturbances in the capacity to make discriminations between cool stimuli might be revealed that previously went unnoticed. Results of experiments testing these assumptions indicated that rats can use their snouts to make discriminations of 1 degree C or less, that their acuity is better in the cool than in the warm range, and that somatosensory ablations produce moderate to severe disturbances in the capacity to discriminate between cool stimuli but only slight transitory disturbances in this capacity for warm stimuli. Additionally, the results suggest that the sensorimotor cortex may be involved in the rat's thermal discriminative capacity.