Further studies of physiological concomitants of hypnosis: skin temperature,heart rate and skin resistance

Forehead skin temperature, heart rate and palmar skin resistance were recorded during passive hypnosis and compared with corresponding data obtained during the resting awake condition in a group of highly hypnotizable subjects experienced in self-hypnosis. Similar physiological measures were also monitored during experimental periods when subjects were experiencing suggested environmental conditions of cold and heat in hypnosis as compared with imagining the stress conditions. The data from these subjects were also compared with those obtained from a randomly selected group of people who were low in waking suggestibility and had never been hypnotized. The results indicate that the differences in mean physiological parameters were greatest between the two subject groups, although some noteable differences were also apparent between hypnosis and the awake condition within the experimental group.     

Influence of cold pain in the hand on skin impedance, heart rate and skin temperature

Twenty-one healthy volunteers took part in the study, the aim of which was to determine the influence of acute pain on skin impedance, skin temperature and heart rate. Acute pain was induced by cold exposure. Skin impedance, heart rate and facial skin temperature were recorded before, during and after the painful stimulation. The skin impedance increased during the stimulation by 24%, heart rate by 6% and skin temperature by 6%. The results show that changes in skin impedance as a result of acute pain can easily be recorded and could be a useful tool in monitoring acute pain. The technique is better than monitoring heart rate or skin temperature.     

The changes of skin temperature on hands and feet during and after T3 sympathicotomy for palmar hyperhidrosis

Unilateral thoracic sympathectomy in patients with palmar hyperhidrosis causes a skin temperature drop in the contralateral hand. A cross-inhibitory effect by the post-ganglionic neurons innervating hands is postulated as a mechanism of contralateral vasoconstriction. The purpose of our study was to evaluate whether this cross-inhibitory effect also occurs in the feet. Twenty patients scheduled for thoracoscopic sympathicotomy due to palmar hyperhidosis were studied. Right T3 sympathicotomy was performed first, followed by left T3 sympathicotomy. The thenar skin temperatures of both hands and feet were continuously monitored using a thermometer and recorded before induction of anesthesia, during the operation, 4 hr after and 1 week later. Following right T3 sympathicotomy, the skin temperature of the ipsilateral hand gradually increased, however the skin temperature of the contralateral hand gradually decreased. Immediately after bilateral sympathicotomy, the skin temperature differences between hands and feet increased, but these differences decreased 1 week later. Our results show that cross-inhibitory control may exist in feet as well as in the contralateral hand. Thus, the release of cross-inhibitory control following T3 sympathicotomy results in vasoconstriction and decrease of skin temperature on the contralateral hand and feet. One week later, however, the temperature balance on hands and feet recovers.     

Instructed heart rate control in a high heart rate population

Forty college students were selected from a large number of introductory psychology students on the basis of high heart rate during an initial screening session. Subjects were then contacted and participated in two additional sessions during which heart rate, respiration rate, and skin conductance measures were obtained. Each session consisted of a baseline period followed by five trial periods during which subjects attempted to control their heart rate or performed a visual tracking task. Subjects were randomly assigned to one of four groups. One group served as a control and monitored a visual feedback display driven by their own heart rate but received no instructions to decrease their heart rate. In contrast, the three heart rate control groups were instructed to decrease heart rate during the trial periods by utilizing a relaxation procedure, proportional biofeedback, or proportional biofeedback plus criterion information. No group differences were present during the baseline periods. During feedback trials, however, all the training groups differed from the control in heart rate but did not differ from each other. It is suggested that feedback displays may not facilitate heart rate reduction beyond the level achieved by instructing subjects to use a general relaxation procedure.     

Ice-water hand immersion causes a reflex decrease in skin temperature in the contralateral hand

Cutaneous receptors stimulated by ice-water immersion of one hand will increase sympathetic nerve activity to the palm skin in the nonimmersed contralateral hand and reduce blood flow, reflecting on a decrease in skin surface temperature under a constant ambient environment. To test the hypothesis that gender might affect the contralateral vasoconstrictor response, we analyzed the spatiotemporal pattern of palm skin surface temperature during ice-water immersion for 10 min using thermography in eight males and eight females. As soon as the left hand was immersed in ice-water, palm skin temperature in the nonimmersed right hand quickly decreased in all subjects, particularly in the periphery of the digits and palm. The reduction in skin temperature was short-lasting in 63% of males and 38% of females, but it lasted throughout immersion in the remaining subjects. The average decrease in palm skin temperature was not significantly different between males and females, though it tended to be greater in males. The mean arterial blood pressure significantly increased and heart rate decreased during immersion in males, whereas no substantial cardiovascular changes were observed in females. Cold sensation was well coincident with the appearance of a reduction in the palm skin temperature. In consideration of all these results, we suggest that cutaneous cold stimuli increased skin sympathetic nerve activity in the nonimmersed hand and reduced skin blood flow. We also contend that gender difference in the contralateral vasoconstrictor response was denied because the time course and magnitude of the decrease in palm skin temperature were not different between males and females.     

Effect of ambient temperature on the thermal profile of the human forearm,hand, and fingers

Forearm, hand, and finger skin temperatures were measured on the right and left sides of seven resting men. The purpose was to determine the bilateral symmetry of these segmental temperature profiles at ambient temperatures from 10 to 45°C. Thermistors placed on the right and left forearms, hands, and index fingers were used to monitor the subjects until equilibration was reached at each ambient temperature. Additionally, thermal profiles of both hands were measured with copper-constantan thermocouples. During one experimental condition (23°C ambient), rectal, ear canal, and 24 skin temperatures were measured on each subject. Average body and average skin temperatures are given for each subject at the 23°C ambient condition. Detailed thermal profiles are also presented for the dorsal, ventral, and circumferential left forearm, hand, and finger skin temperatures at 23°C ambient. No significant differences were found between the mean skin temperatures of the right and left contralateral segments at any of the selected ambient temperatures.     

Digital Temperature Autoregulation and Associated Cardiovascular Changes

Two studies were designed to explore the extent to which individuals can learn to control their digital skin temperature and how such learning might be associated with changes in cardiovascular functioning. In the first experiment, 8 male and 8 female subjects were assigned to two experimental conditions in which either increases or decreases in digital skin temperature were rewarded. Subjects were given 2 baseline days and either 5 or 9 days of training. Analysis of the temperature data indicated that the differences between conditions were due to changes primarily in the decrease direction. All changes were bilateral. Analysis of heart rate revealed a sex difference in the cardiac response to voluntary vasodilation. Data from two plethysmographic measures are also presented. In the second experiment, it was demonstrated that lowering the ambient temperature decreased the ability of 8 subjects to voluntarily vasodilate.     

The effects of intention and mental imagery on the learning of peripheral skin temperature control

This study aimed to examine the effects of intention to raise the skin temperature and the use of warm imagery as a strategy for the control of skin temperature without biofeedback. Thirty-two adult female subjects were assigned to either one of following four groups: intention-imagery (It-Im), intention-no imagery (It-NIm), no intention-imagery (NIt-Im), and no intention-no imagery (NIt-NIm) groups. The finger-tip skin temperature was measured during following sessions: first trial, first rest, second trial, and second rest sessions. Results were as follows: the It-Im group was able to raise its skin temperature in the first and the second trial sessions, the It-NIm and NIt-Im groups were not able to raise their skin temperature in any sessions, and the skin temperature of the NIt-NIm group was raised during the first trial session, but it was stopped at the second trial session. These results suggest that both intention and strategy are necessary for the control of skin temperature without biofeedback.     

The effect of skin temperature on performance during a 7.5-km cycling time trial

Aerobic exercise performance is seriously compromised in the heat. Possibly, a high skin temperature causes a rating of perceived exertion (RPE)-mediated decrease in exercise intensity. The purpose of this study was to determine the effect of skin temperature on power output during a 7.5-km cycling time trial. Thirteen well-trained male subjects performed a 7.5-km cycling time trial at 15°C and 50% relative humidity (CONTROL), with radiative heat stress during the time trial, and with (PRECOOL) or without (HEAT) precooling. Heat stress was applied by infrared heaters positioned in front of the cycle ergometer between 1.5 and 6.0 km. Skin, rectal, and pill temperature, power output, heart rate, and RPE were measured during the trial. Despite the lower mean skin temperature at the start of the time trial for PRECOOL compared to HEAT (-2.1 ± 0.7°C; P < 0.01) and CONTROL (-1.8 ± 0.6°C; P < 0.05), and a greater increase in mean skin temperature during the heat stress period for PRECOOL (4.5 ± 1.0°C) and HEAT (3.9 ± 0.8°C) than for CONTROL (-0.3 ± 0.6°C; P < 0.01), no differences in power output were found between HEAT (273 ± 45 W) and CONTROL (284 ± 43 W; P = 0.11) and between HEAT and PRECOOL (266 ± 50 W; P = 0.47). Power output during the time trial was greater for CONTROL than for PRECOOL (P < 0.05). Additionally, no differences were observed in core temperature measures, HR, and RPE. Skin temperature does not affect the selection and modulation of exercise intensity in a 7.5-km cycling time trial.     

Electrodermal Nonresponding Among College Undergraduates: Temporal Stability, Situational Specificity, and Relationship To Heart Rate Change

Based on a large screening project, 24 electrodermal nonresponders to nonsignal tones were chosen from an undergraduate population and compared on multiple electrodermal, heart rate, and personality measures to an equal number of randomly selected control subjects. Questions addressed in this study included the reliability of the nonresponder category with repeated testing, its stability across situations, its concurrent relationship with other psychophysiological measures, and its ability to predict scores on more standardized measures of individual differences. It was determined that nonresponders continued to produce smaller specific skin conductance responses (SCRs) during a second testing session two weeks after the initial screening, and these differences remained when subjects were tested under signal conditions. However, 50% of the initial nonresponders did produce SCRs by the completion of all testing. Nonresponders and controls differed on other electrodermal measures as well, with nonresponders producing fewer spontaneous fluctuations under all conditions and lower skin conductance levels during initial screening and under signal conditions. Nonresponders and control subjects also differed in heart rate response during the signal procedure. Control subjects produced the anticipated cardiac deceleration, whereas nonresponders produced a pronounced heart rate increase. The two groups did not differ on measured personality characteristics, but when nonresponders were divided into subgroups based on consistency of response pattern, several differences did emerge.     

BILATERAL DIFFERENCES IN SKIN RESISTANCE AND VASOMOTOR ACTIVITY

Bilateral basal skin resistance (BSR) and bilateral photoplethysmographic vasomotor measures were obtained for 16 Ss. Ten Ss were found to have bilateral differences in BSR. The direction of these differences was not related to handedness. Bilateral differences in vasomotor resting levels, variability, and reactivity were also observed in the majority of Ss. Some relationships among bilateral patterns of vasomotor responsivity and BSR emerged. Thus, the side of the body having lower BSR was identical to the side with the lesser vasomotor constriction during experimental stress (breath holding). Also, the side of the body having the lower vasomotor amplitude had less vasomotor variability. The findings suggest that asymmetry of autonomic activity is typical rather than atypical for the normal individual, and that various autonomic variables form patterns of asymmetry.     

Effect of non-uniform skin temperature on thermoregulatory response during water immersion

The present study investigated the effect of non-uniform skin temperature distribution on thermoregulatory responses and subjective thermal sensation during water immersion. Ten healthy male subjects carried out 60 min water immersion twice, once with uniform (UST) and once with non-uniform (NUST) skin temperature. In UST condition, subjects immersed at 29 degrees C in naked condition, while in NUST condition, subjects immersed at 26 degrees C with partial coverage wetsuit (PCWS). The PCWS covers trunk region, upper arms, and thighs. The non-uniform skin temperature distribution, higher at trunk and lower at distal extremities, was observed in NUST condition. Shivering thermogenesis was not influenced by the skin temperature distribution at the experimental condition of this study. On the other hand, the tissue insulation (I (tissue)) was significantly higher in NUST condition compared to the UST condition. The increment of I (tissue) might have been caused by the peripheral vasoconstriction induced by the cold input from the distal extremities in NUST condition. The higher I (tissue) in NUST condition might lead to the significantly higher esophageal temperature compared to UST condition. No difference was observed in thermal sensation between the two conditions. Subjects felt slightly more comfortable in NUST condition than in UST condition. In conclusion, the non-uniform skin temperature distribution, higher at trunk and lower at distal extremities, might affect the peripheral vasoconstriction to increase the I (tissue). On the other hand, shivering thermogenesis and subjective thermal sensation were not affected by the non-uniform skin temperature distribution at the present experimental condition.     

The metabolic response to skin temperature

Experiments were done to assess that fraction of the metabolic response to external cold exposure, which is attributable to skin temperature. In 5 conscious and closely clipped goats the metabolic rate was determined at various stable levels of skin temperature in the range from 13 to 41°C, while core temperature was kept constant at 38.8°C. Skin temperature was manipulated by a rapidly circulating shower bath, while core temperature was controlled by means of heat exchangers acting on arterial blood temperature in a chronic arteriovenous shunt. The metabolic response to skin temperature fell into two clearly discernible sections: a first zone with skin temperatures above 25–30°C, within which the metabolic rate rose at a rate of –0.34±0.07 W/kg·°C with decreasing skin temperature, and a second zone with skin temperatures below 25–30°C, within which the metabolic rate either plateaued or even grew smaller with further decreasing skin temperature. It is concluded that the relationship between skin temperature and metabolic rate does not directly reproduce the temperature-response curve of cutaneous cold receptors but also reflects a complex interaction of several factors, including an unspecific temperature effect on muscle metabolism.     

Autonomic Activity During Anticipation of An Aversive Tone in Noninstitutionalized Sociopaths

Fifteen noninstitutionalized, compulsive-gambler sociopaths and 15 controls were run in a modification of Hare's (1965b) gradient of fear paradigm. Both heart rate and bilateral skin conductance were averaged during 8 3-sec intervals prior to the presentation of a 95dB tone. The controls showed both earlier and larger electrodermal anticipation of the tone than the sociopaths. For both groups of subjects, electrodermal anticipation of the tone began sooner and was larger in amplitude in the right hand than in the left hand. There were no significant heart rate differences between the two groups of subjects.     

Laterality of Body Focus and Digital Skin Temperature in Patients with Raynaud''s Disease

The purpose of the present study was to assess the relationship between lateralization of body image and right versus left vasomotor activity. Fifteen right-handed female patients suffering from idiopathic Raynaud's disease demonstrated a relationship between the extent of right lateralization of body image and bilateral digital skin temperature during a controlled temperature stress test. In addition, subjects showing a reliable right side awareness demonstrated more unilateral vasospastic attacks in their right hand than their left hand white subjects showing no clear right lateralization by body image reported more left hand attacks than right hand attacks. These results were taken as consistent with previous work on the relationship between skin conductance and lateralization of body image.     

Changes in rectal and mean skin temperature in response to suggested heat during hypnosis in man

Rectal temperature, mean skin temperature and heart rate were recorded in 7 subjects during hypnosis, induced either alone or while sensations of heat were suggested. During hypnosis alone, a fall in the heart rate of about 10 beat·min^?1 was the only autonomic response observed; body temperatures were unaltered. In contrast, during hypnosis with suggestion of heat, the following changes occurred: (1) Mean rectal temperature decreased 0.20°C (p<0.05) within 50 min. Its mean time course differed significantly from that for hypnosis alone (p<0.001). (2) Comparison of individual rectal temperature time sequences showed that in fact this temperature only declined in 4 subjects out of 7, and tended to form a plateau located 0.35°C below the value of the preceding waking state. Despite reinforcement of heat suggestion, the plateau continued until the end of the hypnotic trance. (3) Mean skin temperature tended to rise. (4) When hypnosis with suggestion ceased, both rectal and skin temperatures very slowly returned to their levels during the preceding waking state.     

Psychophysiological responses to the Stroop Task after a maximal cycle ergometry in elite sportsmen and physically active subjects.

Physical fitness moderates the psychophysiological responses to stress. This study attempts to determine whether the degree of fitness could affect the response to physical and psychological stress after comparing two groups of men with good physical fitness. Saliva samples from 18 elite sportsmen, and 11 physically active subjects were collected to determine hormonal levels after carrying out a maximal cycle ergometry. Heart rate and skin conductance level were continuously recorded before, during, and after a modified version of the Stroop Color-Word Task. With similar scores in trait anxiety and mood, elite sportsmen had lower basal salivary testosterone, testosterone/cortisol ratio, and HR before an ergometric session than physically active subjects, but no differences were found in salivary cortisol and blood pressure. Salivary testosterone and cortisol responses were lower and testosterone/cortisol ratio responses higher in elite sportsmen. During the Stroop Task, elite subjects showed lower heart rate and skin conductance level over the entire measurement period, and greater heart rate recovery with respect to the baseline values than physically active subjects. The effects of two standardised laboratory stressors on a set of psychophysiological variables were different when elite sportsmen and physically active subjects were compared.     

Bidirectional changes in digital skin temperature using biofeedback in a cold room

The ability to increase digital skin temperature (DST) of cold extremities or to prevent decreases in DST in a cold environment may be useful clinically in the treatment of Raynaud's disease or in the alleviation of the effects of stressful stimuli. Ten Ss, each of whom participated in five sessions, were studied in a room at 20°C. Each session was divided into 5-minute trials during which Ss either received auditory biofeedback of DST and tried to increase or decrease DST or received no feedback and merely sat quietly (Baseline trials). There were significant changes in DST during Baseline trials; these changes were different at different times during the session. The difference between Increase and Decrease trials was significant. The DST decrease during Decrease trials was significantly different from the change during corresponding Baseline trials, while the Increase trial DST, although of the same magnitude as the decrease trial, did not differ significantly from its corresponding Baseline trials DST.     

Body temperature and heart rate relationships during submaximal bicycle ergometer exercises

Summary Twenty-three male subjects performed submaximal exercise at approximately 80% max on a bicycle ergometer. Rectal temperature, skin temperatures, and heart rate measurements were taken during the exercise and during the corresponding recovery periods. The lag in body temperature (rectal temperature and mean body temperature) responses at the onset of exercise or recovery from exercise was shown in comparison with heart rate. Certain differences existed in the relationship between body temperature and heart rate during the exercise and the recovery period. The correlation coefficient of body temperature with heart rate was high from the 24th min of exercise until the 21st min of the recovery period. The regression equation of post-work rectal temperature on heart rate at moderate work loads (approximately 80% max) in the present study was similar to the equation at light work loads (25∼35% max) for data reported from different laboratories. However, at the termination of exercise the regression equation of rectal temperature on heart rate at light work loads from different laboratories does not agree with the equation of rectal temperature on heart rate at moderate exercise, in the present study. There is good agreement with the equation from the maximum state at a moderate exercise (times of maximum heart rate against maximum body temperature). The correlation coefficients for rectal temperature on heart rate at the maximum state were high. The relationship between body temperature and heart rate at the termination of light exercise is similar to that between these two parameters at the maximum state for moderate exercise.     

Electrodermal Activity Recorded Concomitantly From the Subject's Two Hands

Electrodermal activity is the most frequently monitored psychophysiological and most investigators assume that the activity recorded from one hand is representative of the whole system. A few earlier studies of possible bilateral differences in this activity frequently noted such differences in response magnitude and pre-response level. The present study examines bilateral differences not only in response magnitude and pre-response level but also in response latency, recruitment time, and recovery. Relationships with handedness are also considered. It is concluded that although bilateral differences were often noted, the activity from one hand is strongly related to the activity concomitantly recorded from the other hand.