An analysis of boluntary control of skin temperature using the cross-correlation technique

Abstract

Using the cross correlation technique, the relation among finger skin temperatures during voluntary control training was examined. Ten female undergraduates were asked to decrease the skin temperature of their index finger on the dominant hand. The skin temperature of both hands was remotely measured by infrared telethermography. The subjects received five training sessions. Each session consisted of 3 periods. The pretraining period (about 10 minutes) was given for the purpose of stabilizing their finger temperature. In the training period, the thermographic display was presented for 15 minutes as the feedback stimulus and each subject was instructed that rewards (\100) were given when they lowered the finger temperature with every 1℃. Then the post training period was given for five minutes. The results showed training effects in eight out of ten subjects. The cross correlation technique, however, revealed that the only two examples showed gradual temperature changes session by sesion. In the case of the subject(MM), who showed gradual decrease in skin temperature of index finger through the sessions, the skin temperature of all the fingers changed simultaneously and the cross correlation coeffecients among fingers were significantly high in the earlier sessions. But in the 3rd session, the coeffecients among fingers that innervate the same motor nerve became higher than those that innervate different motor nerves. These results indicate the possibility of the mediation by skeletal muscles in the biofeedback training of skin temperature. In the 4th session, however, the coefficients among fingers that innervate the same motor nerve also became lower. This suggests the skin temperature of the index finger decreased independently of other fingers during this session. The subject(KK)also showed gradual decrease in skin temperature, but the temperature of all his fingers decreased simultaneously and his index finger temperature decreased dependently on other fingers in the later sessions. These findings suggest that the changes of autonomic response are established by the mediation of skeletal muscles first, then the autonomic response alone changes.