Skin Temperature Levels Research Articles

Determining the different phases of torpor from skin- or body temperature data in heterotherms

Technological innovations have made heat-sensitive data-loggers smaller, more efficient and less expensive, which has led to a growing body of literature that measures the skin- or body temperatures of small animals in their natural environments. Studies of this type on heterothermic endotherms have prompted much debate regarding how to best define ‘torpor’ expressions from skin- or body temperature data alone. We propose a new quantitative method for defining torpor ‘entries’, ‘arousals’ and ‘stable torpor periods’ whilst comparing the results to ‘torpor bout’ durations identified using only the torpor cut-off method. By decomposing a torpor bout into ‘entries’, ‘stable torpor periods’, and ‘active arousals’, we avoid biases introduced by using strict threshold temperature values for the onset of torpor, thereby allowing better insight into individual use of torpor. We present our method as an easy-to-use function written in R-code, offering an un-biased and consistent methodology to be applied on skin- or body temperature measurements across datasets and research groups. When testing the function on a large dataset of skin temperature data collected on three bat species in Norway (Plecotus auritus: Nind = 39; Eptesicus nilssonii: Nind = 11; Myotis brandtii: Nind = 10), we identified 461 complete torpor bouts across species. More than 40% of the torpor bouts (Nbouts = 192) did not contain stable torpor periods, because the bats aroused before they had reached a stable skin temperature level. Furthermore, only considering ‘torpid’ and ‘euthermic’ temperature values by applying strict cut-off thresholds led to potentially large underestimations of torpor bout durations compared to our quantitative determination of the onset and termination of each torpor bout. We highlight the importance of differentiating between torpor phases, especially for active arousals that can be very energetically expensive and may alter our evaluation of the actual energetic savings gained by an individual employing torpor.

Impact of thermal stress on physiological, behavioural and biochemical parameters in native and crossbred goats

The present study was undertaken to investigate the association of the temperature-humidity index with physiological, biochemical and behavioural responses in Malabari, crossbred and Attappady black goats of Kerala, India. A positive correlation was noticed between in-house temperature (IT) and temperature-humidity index (THI) with respiration rates, rectal temperatures, heart rate and skin temperature levels of breeds at 2.00 PM and 5.00 PM. Biochemical and endocrines parameters, blood gases and electrolytes were analysed during the 2nd, 32nd and 60th day of the study. Alterations in physiological parameters were more significant in Malabari goats. However, a negative correlation was observed between in-house relative humidity and all physiological parameters during all the different times. Behavioural patterns were influenced by increased IT and THI and the breeds spent more time in standing position during heat stress. A significant difference was observed within the study period in the pO2, Na+, HCO3- and blood pH. A significant difference was observed between the breeds for K+, Cl- and HCO3- levels. A significantly higher glucose level on the 32nd day and a lower total cholesterol level in the latter half of the experimental period were noticed in Malabari and crossbred. Mean total protein levels of all the breeds were significantly increased on the 32nd day. Increased GGT levels were observed in the first half of the experimental period in all breeds. Higher cortisol levels in Malabari and crossbred could be estimated in the first half of the experiment. Although Malabari showed higher T3 levels on the 32nd day compared to other breeds, within the breeds no significant difference in T3 levels could be noticed. However, significantly higher T4 values were recorded on the 32nd day and 60th day only in Crossbred breeds when the IT and THI were high. Thus it has been shown that heat stress was affecting the physiology, metabolism and behaviour of breeds. The increase in respiratory rate and rectal temperature were the first signs of heat stress in these breeds. The physiological manifestations of stress were the greatest for Malabari goats and the least for Attappady black.

Autonomic changes as reaction to experimental social stress in an inpatient psychosomatic cohort.

ObjectivesPatients with psychosomatic disorders suffer from social isolation that might further lead to destabilization and exacerbation of bodily symptoms via autonomic pathways. We aimed to investigate the influence of controlled social stress (model of social ostracism) on the autonomic nerve system (ANS) in an inpatient cohort with psychosomatic disorders.MethodsWe examined heart rate variability (HRV), skin conductance (SC) and skin temperature (ST) as well as ECG-derived respiration rate (EDR) and subjective reports on stress during exposure to experimental social stress (cyberball game). Data were collected from 123 participants (f:m = 88:35, 42.01 ± 13.54 years) on admission and upon discharge from the university psychosomatic clinic. All data were recorded during baseline, inclusion and exclusion phases of the cyberball game as well as during the recovery phase.ResultsWe found significant changes between admission and discharge with a decline in parasympathetic-related HRV parameters (SDRR −3.20 ± 1.30 ms, p = 0.026; RMSSD: −3.77 ± 1.28 ms, p = 0.007) as well as a decrease in SC (−0.04 ± 0.17 μS, p = 0.019) and EDR (−0.01 ± 0.01 Hz, p = 0.007), suggesting a drop in sympathetic tonus, with no changes in ST (p = 0.089) and subjective stress levels (p = 0.322). HRV parameters decreased during the cyberball game (SDRR p = 0.026; RMSSD p = 0.002; lnHF p < 0.001). In contrast, both SC (p < 0.001) and EDR (p < 0.001) increased during the game with SC being slightly lower during the exclusion phase. This can point toward a stimulation of sympathetic nervous system during game participation, which was concordant with the rise in subjective stress values (p < 0.001). ST showed a continuous, unspecific rise over time (p < 0.001).ConclusionOur data demonstrate the decrease of ANS parameters during experimental social stress when data upon discharge were compared to those upon admission. These results are partially contradictory to previous studies that showed a rise in HRV in a psychiatric cohort over the course of (outpatient) treatment. Further research is required to help attributing these differences to effects of treatment or acute states relating to admission to or discharge from a psychosomatic department.

Thermal imaging in total knee replacement and its relation with inflammation markers.

Total knee replacement is an end-stage surgical treatment of osteoarthritis patients to improve their quality of life. The study presents a thermal imaging-based approach to assess the recovery of operated-knees. The study focuses on the potential of thermal imaging for total knee replacement and its relation with clinical inflammatory markers. A total of 20 patients with bilateral knee replacement were included for thermal imaging and serology, where data was acquired on pre-operative day and five post-operative days. To quantify the inflammation, the temperature-based parameters (like mean differential temperature, relative percentage of raised temperature) were evaluated from thermal images, while the clinically proven inflammation markers were obtained from blood samples for clinical validation. Initially, the knee region was segmented by applying the automatic method, subsequently, the mean skin temperature was calculated and investigated for a statistical relevant relationship with inflammatory markers. After surgery, the mean skin temperature was first increased (>2.15 ℃ for different views) then settled to pre-operative level by 90th day. Consequently, the mean differential temperature showed a strong correlation with erythrocyte sedimentation rate (r > 0.893) and C-reactive protein (r > 0.955). Also, the visual profile and relative percentage of raised temperature showed promising results in quantifying the temperature changes both qualitatively and quantitatively. This study provides an automatic and non-invasive way of screening the patients for raised levels of skin temperature, which can be a sign of inflammation. Hence, the proposed temperature-based technique can help the clinicians for visual assessment of post-operative recovery of patients.

Mitigating Interactive Performance Degradation From Mobile Device Thermal Throttling

Mobile devices are limited in mass and volume, reducing the viability of active device cooling implementations. This requires the use of less effective passive techniques to maintain device skin temperature levels. Application performance demands on a modern mobile device are driven by sustained performance workloads, such as 3-D games, virtual, and augmented reality. Mobile system-on-chips (SoCs) have corresponding increases in performance through both architectural changes and frequency of operation increases, which has resulted in the peak power consumption exceeding the sustainable thermal envelope defined by device skin temperature requirements. Existing thermal throttling techniques mitigate this by capping the frequency of operation of the SoC. Through experimentation with a modern smartphone platform using sequences from real-world applications, we demonstrate in this letter that frequency capping (FC) can have a significant effect on the performance of interactive applications, increasing the number of frame rate defects by up to 146%. We propose task utilization scaling, a new lever for thermal throttling, which scales performance for critical interactive periods by the same factor as noncritical periods. Experiments demonstrate that the proposed approach can result in a decrease in frame rate defects of up to 18% compared with FC or a skin temperature reduction of up to 2°C.

Development of physiological human model considering mist wettedness for mist-spraying environments

The thermal state of the human body is closely related to thermal sensations and thermal comfort and can be estimated using a physiological human model. However, the feasibility of its prediction models in a mist-spraying environment has not been examined. The present study confirmed the applicability of existing prediction models (two-node model (2NM) and three-node model (3NM)) in outdoor and mist-spraying environments. Additionally, the evaporative heat loss caused by mist wetting in the human body (mist wettedness)—which has been overlooked—was measured using a heating globe thermometer controlled at the skin-temperature level, and on the basis of the results, the existing prediction models were modified. In the outdoor environment, the existing and modified models predicted the skin temperature identically, with errors of 0.30 °C (2NM) and 0.24 °C (3NM), for 10 min. In the mist-spraying environment, the skin-temperature results for the existing models stabilized and did not reflect the continuously decreasing experimental results, but the modified models reflected the continuously decreasing tendency of the experimental skin-temperature results, with errors of 0.52 °C (2NM) and 0.56 °C (3NM). When the effective area factor (ηmist = 0.5) of the mist droplets was applied to the modified prediction models, the mist wettedness contributions to the total heat loss from the body surface were 40.4% (2NM) and 37.9% (3NM). Therefore, the mist wettedness was identified as a significant environmental factor affecting the heat loss on the human body, and these models can provide better understandings of the physical phenomena in mist-spraying environments.

Effects of aroma self-foot reflexology on peripheral neuropathy, peripheral skin temperature, anxiety, and depression in gynaecologic cancer patients undergoing chemotherapy: A randomised controlled trial.

Chemotherapy-induced peripheral neuropathy (CIPN) can interfere with activities of daily living and can negatively affect symptoms. Thus, this study aimed to develop and implement an aroma self-foot reflexology regimen based on Cox's Interaction Model of Client Health Behaviour (IMCHB) as an intervention that can be self-performed at home and at any time. The effects of aroma self-foot reflexology on peripheral neuropathy, peripheral skin temperature, anxiety, and depression were examined in patients with gynaecologic cancer who were undergoing chemotherapy. This randomized controlled trial included 32 experimental and 31 control patients with CIPN. Data were collected using self-reported questionnaires (CIPN assessment tool, HADS). In the experimental group, peripheral neuropathy, peripheral skin temperature, anxiety, and depression were measured before and after aroma self-foot reflexology therapy for 6 weeks. The control group was provided with identical aroma self-foot reflexology training 6 weeks later and underwent the intervention at that time. The intervention resulted in lower levels of symptoms of peripheral neuropathy, less interference with activities (p < .001), and higher peripheral skin temperature level (p < .001). Anxiety and depression decreased in the experimental group (p < .001). The ratio of borderline and definite cases of anxiety and depression did not differ between groups. An aroma self-foot reflexology intervention can reduce CIPN, anxiety, and depression in gynaecologic cancer patients. Further research is required to assess the effects of differences in the content of the intervention and the effects of various numbers of applications and durations of applications based on each individual patient's condition.

Применение релаксационного биоуправления в лечении и реабилитации пациентов с заболеванием голосового аппарата

The article deals with the psychological treatment of patients with voice disorders using the latest computer technology psychotherapy. The paper describes a method of psychological treatment based on biofeedback relaxation. The data on the dynamics of changes in physiological parameters, psycho-emotional background, as well as the state of the voice functions, taking into account the treatment. It describes the techniques and methods of work on the unit. On the basis of the data evaluated the effectiveness of this method in rehabilitation of voice function in patients with voice disorders. Substantiates the proposition that biofeedback relaxation is highly effective and non-invasive method of treatment and health effects in the treatment and rehabilitation of diseases of the vocal apparatus, helping to reduce the level of anxiety, psychosocial stress, as well as increase the level of vitality. Using biorelaxation technology can increase stress levels and ensures the production of constructive behavior strategies in stress situations. Relaxing biofeedback helps to reduce muscle tension and raising the level of skin temperature as autonomic response of the patients at the beginning and end of the training differed significantly, and the vegetative balance towards the end of the course was shifted toward parasympathetic reactions.

Explaining the individual processes leading to adaptive comfort: Exploring physiological, behavioural and psychological reactions to thermal stimuli

Behavioural, physiological and psychological adaptive processes are presumed reasons for the discrepancies between predicted mean vote and observed comfort votes during field studies. However, few are known about the individual portions of these processes. An experimental design was developed, which aims at identifying those portions and is meant for climate chambers with operable windows facing the exterior. This article looks in detail at behavioural and physiological reactions together with their effect on the perceived level of comfort. By means of multivariate regression analyses, these reactions are analysed in order to assess differences due to variations in indoor/outdoor conditions as well as the number of interactive opportunities. One of the results shows that the restriction to keep the window closed is counterbalanced by an increased amount of physiological reactions, such as an increased level of skin temperature, together with an increase of still permitted actions such as drinking. The results highlight the importance of detailed insights into single aspect of adaptive processes for a better understanding of the phenomenon called ‘adaptive comfort’. Such approach is novel and important because a detailed knowledge and quantification of the occupant’s comfort perception in naturally ventilated buildings permits a planning with less uncertainty.

Psychophysiologic stress reduction in surgery

We read with interest the paper entitled Effects of Intraoperative Breaks on Mental and Somatic Operator Fatigue. This paper describes a randomized clinical trial authored by Engelmann and colleagues, who noted that ‘‘work breaks during complex laparoscopic surgery can reduce psychological stress and preserve performance without prolongation of the operation time compared with the traditional work scheme’’ [1]. Similar to the working group of Ure, our research team conducted a psychophysiologic study including 25 surgeons, who accomplished 51 surgeries. The volunteers were monitored over the period of 1 working day with a real-time working telemedical system [2]. The strain markers in our study included heart rate (HR), breathing rate (BR), skin temperature (ST), and three self-report questionnaires answered on a mobile phone before and after each surgery. After the procedures, intraoperative function (primary surgeon, first assistant surgeon), level of complication, and application of lead aprons were documented on the mobile phone. Our results clearly indicated that the function during surgery and the wearing of lead aprons had an impact on the intraoperative stress of the surgeon. Surgeons in the function of primary operator showed higher levels of HR, BR, and ST than they experienced in their role as first assistant surgeon. Furthermore, an additional increase in load was documented during operations with lead aprons. The answers given in the self-report questionnaires supported the findings. The primary surgeons evaluated the intraoperative stress significantly higher than the first assistant surgeons, and the application of lead aprons also resulted in higher stress levels. For this reason, we suggest that apart from consideration of intraoperative work breaks within one surgery, careful preoperative planning of consecutive surgeries that allows for both an alternation of intraoperative functions and a rotative system for the application of lead aprons should be taken into account.

Circadian rhythms of locomotor activity and temperature selection in sleepy lizards, Tiliqua rugosa

This study examined whether the daily rhythms of locomotor activity and behavioural thermoregulation that have previously been observed in Australian sleepy lizards (Tiliqua rugosa) under field conditions are true circadian rhythms that persist in constant darkness (DD) and whether these rhythms show similar characteristics. Lizards held on laboratory thermal gradients in the Australian spring under the prevailing 12-hour light : dark (LD) cycle for 14 days displayed robust daily rhythms of behavioural thermoregulation and locomotor activity. In the 13-day period of DD that followed LD, most lizards exhibited free-running circadian rhythms of locomotor activity and behavioural thermoregulation. The predominant activity pattern displayed in LD was unimodal and this was retained in DD. While mean levels of skin temperature and locomotor activity were found to decrease from LD to DD, activity duration remained unchanged. The present results demonstrate for the first time that this species' daily rhythm of locomotor activity is an endogenous circadian rhythm. Our results also demonstrate a close correlation between the circadian activity and thermoregulatory rhythms in this species indicating that the two rhythms are controlled by the same master oscillator(s). Future examination of seasonal aspects of these rhythms, may, however, cause this hypothesis to be modified.

Hand Skin Temperatures Associated with Local Hand Discomfort under Whole-body Cold Exposure

This study aimed at pointing out the local thermal effects and subjective responses to cold air exposures of gloved hands in conditions of similar hand heat loss rates. Thirteen males and 13 females, lightly clothed (0.6 clo), participated in three separated experimental sessions (once a week), while sitting for 105 min in a climatic chamber at an operative temperature of 19°C. Subjects' hands were exposed in a ventilated cold box (air velocity=2.5 m·s−1) at one of three temperatures (8°C, 10°C or 14°C) depending on the dry heat exchange coefficient of the gloved hands. The temperature of the box was chosen to induce similar heat loss rates across conditions. Main results showed that local skin temperatures can be divided in 3 categories: 4 fingers (coolest), a thumb, back and palm (least cool). Female had lower skin temperatures than males but their local thermal discomfort was found to be similar for the same local skin temperature levels. As a consequence, the durations of the accepted exposures without discomfort were shorter in females. Discrepancies between male and female responses are discussed in terms of different hand skin blood flows. A practical aspect of our results concerns the glove thermal insulations which are obviously too poor at the finger levels, a factor determinant for discomfort occurrence in case of cold hand exposures.

Thermoregulatory Control of Feeding and Sleep in Premature Infants*

The aim of the present study was to test the thermoregulatory feeding control hypothesis in sleeping, premature infants. In premature infants, the energy supply from food intake is crucial for (in order of importance): organ operation, body homeothermia, and optimal growth. The Himms-Hagen model of thermoregulatory feeding control involving activation of heat production by brown adipose tissue (BAT) was formulated on the basis of work in (awake) rats. This hypothesis has also been put forward for the human neonate, which can also use BAT to produce metabolic heat. According to the model, feeding episodes occur during a transient increase in body temperature. Feeding is initiated by a dip in blood glucose concentration after sugar uptake by activated BAT. In 14 neonates (bottle-fed on demand), food intake always took place during an increase in skin temperature (+0.19 +/- 0.21 degrees C). Awakening occurred 18 +/- 17 minutes after the minimum skin temperature level had been reached. When feeding time was imposed, feeding was not necessarily situated during an increase in skin temperature, and the sleep duration after food intake increased significantly (+43%). This could be considered as an adaptive response to the short-term sleep deprivation and/or stress elicited by an imposed feeding rhythm. The validity of the model supports the use of on-demand feeding in neonatal care units, in accordance with the infant's physiological body temperature oscillations.

The combined effects of local contact force and lower arm cooling upon cutaneous blood cell velocity of the fingertip

This study investigated the effects of finger contact force (FCF) and lower arm cooling upon cutaneous blood cell velocity (CBV) in the index finger. CBV of the distal finger-pad of the index finger was measured in eight participants while they exerted different FCF of 0.5, 1.0, 1.5, 2.0, 4.9 and 9.8 N, at significantly different mean index finger skin temperatures of 8.0 degrees C (SD 0.4), 14.9 degrees C (SD 0.3) and 30.9 degrees C (SD 0.5). These three levels of skin temperature were achieved by lower arm immersion in water at 5, 13 and 32 degrees C, respectively. Main effects in CBV of FCF (P<0.001) and water temperature condition (P<0.001) were evident and a significant interaction (P<0.001) between these factors indicated an exponential decay in CBV as FCF was increased in each water temperature condition. Mean decay constants (d) of three mono-exponential functions were significantly different from each other (P<0.05) and their values for the 5, 13 and 32 degrees C immersions were 2.16 N (SD 0.67), 1.41 N (SD 0.31) and 0.87 N (SD 0.21), respectively. In conclusion, a decrease in CBV in these conditions was evident with increasing levels of FCF and the three separate mono-exponential functions describing this relationship were separated by thermal states of the hand. Although decay constants became progressively greater at lower water temperature conditions, a cooler hand also had a lower initial and subsequently smaller decrements in CBV with increases of FCF.

着衣条件の違いによる皮膚温変化が運動時の体温反応と温熱ストレスに与える影響

To clarify the effects of varying skin temperature due to several types of clothing on temperature responses and heat-stress during exercise, we analyzed thermoregulatory responses while wearing various types of sportswear including soccer (SC), baseball (BB), and fencing uniforms (FU), and while wearing water-perfused suits (WS) and vests (WV) during exercise in a hot environment. We also compared these results with those obtained under a semi-nude condition (NU). Eight male subjects performed three 20-min cycling sessions at light intensity (250W/m2) in a room maintained at 28°C (wet-bulb globe temperature, WBGT). The experiment was performed under ten conditions, with six sets of clothing, WS and WV at 14°C (WS14, WV14), 20°C (WS20, WV20) and 26°C (WS26, WV26), and FU, SC, BB or NU. While wearing sport-swear, increases in esophageal (ΔTes), mean skin (Tsk), mean body (Tb) temperature, heart rate (HR), thermal sensation (TS) at the end of exercise, and total sweat loss (msw, tot) during exercise were significantly (p<0.01) higher in BB and FU than in NU. In comparison to WS or WV conditions, ΔTes was significantly (p<0.01) higher under WV conditions than under NU, while there was no significant difference in ΔTes between WS and NU. Tsk, Tb, HR, TS and msw, tot tended to be lower in WS14 and 20, and higher in WV26 than in NU. Under all conditions at the end of exercise, the ΔTes markedly increased when Tsk exceeded 34°C ; and ΔTes was significantly correlated with Tsk (r=0.861, p<0.01) for all conditions except WS14 and 20. For Tsk less than 34°C, however, ΔTes remained constant. ΔTes, Tsk, and Tb significantly correlated with HR (r=0.932, p<0.001), TS (r=0.888, p<0.001), and msw, tot (r=0.961, p<0.001), respectively. These results show that during light exercise under hot conditions, 1) in several types of clothing, a critical level of skin temperature causing core temperature elevation may exist, 2) cooling the skin temperature can alleviate heat-stress due to body temperature elevation, and 3) the semi-nude condition is the simplest method of alleviating core temperature elevation without using body cooling materials such as WS or WV.

Contrôle thermorégulateur de la prise alimentaire et du sommeil chez le nouveau-né prématuré

In premature infants, energy supply from food intake is crucial for organ operating, for the maintenance of body homeothermia and to ensure an optimal body growth. Thermometabolic control of feeding (Himms-Hagen's model), involving brown adipose tissue activation to produce heat, has been argued in rat. This hypothesis has been put forwards for the human neonate who has also brown adipose tissue. According to this model, feeding episode occurred during an episodic increase of body temperature. Feeding is initiated by the dip in blood glucose concentration due to its uptake by the brown adipose tissue activated. The aim of the present study was to validate the hypothesis of a thermometabolic control of feeding in premature infants. In 14 neonates fed by bottle on demand, food intake always took place during an increase of skin temperature (+0.19 ±0.21°C). The awakening occurred 18 ±17 minutes after the minimal skin temperature level. In contrast, when feeding time is imposed, this event is not located during the increase of skin temperature and the sleep time duration following the food intake significantly increased (+43%). This could be considered as an adaptive response to the short-sleep deprivation and/or to the stress elicited by the imposed feeding time. The validity of the model supports to practice “feeding-on-demand” in neonatal care unit in accordance with physiological oscillations in body temperature of the baby.

Electrodermal dissociation of chronic fatigue and depression: evidence for distinct physiological mechanisms

Chronic fatigue syndrome (CFS) has an estimated prevalence between 0.5% and 3%, yet its diagnosis remains contentious. CFS is characterized by subjective symptoms that can be difficult to verify; moreover, depression is a commonly reported CFS complaint, whereas fatigue is a common symptom of depression. Our primary goal was dissociation of these disorders using psychophysiological methods. As previous research has implicated the autonomic nervous system in CFS, we conducted what we believe to be the first analysis of bilateral electrodermal and skin temperature responses of dextral females in a cross-modal orienting task, to investigate differences between these two patient groups and controls. A multivariate analysis of variance (MANOVA) examining three measures of electrodermal activity revealed prestimulus tonic skin conductance levels (SCLs) were markedly lower for the CFS group, with no difference between controls and depressives. Concurrent skin temperature levels were higher for the CFS group than the other two groups. These findings indicate that, despite overtly similar cognitive and symptom profiles, depression and CFS patients can be differentiated with psychophysiological measures. This study adds to the growing body of evidence demonstrating that CFS and depression have distinct neurobiological profiles, consistent with unique aetiologies.

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 degrees C, while core temperature was kept constant at 38.8 degrees 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 degrees C, within which the metabolic rate rose at a rate of -0.34 +/- 0.07 W/kg.degrees C with decreasing skin temperature, and a second zone with skin temperatures below 25-30 degrees 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.

Body temperature set-point and the conscious perception of skin temperature in obese women

Obese and control women were immersed in a bath of water kept at 37 degrees C. Oral temperature was measured. The subjects left hand was placed outside the bath for the local application of thermal stimuli between 20 degrees and 45 degrees C, subjects reporting the most pleasant temperature. The lower oral temperatures and lower levels of skin temperature rated as pleasant by obese women as compared with women of normal body weight or less suggests that in obesity the set-point of body temperature is lowered.

Activity of thermosensitive neurons of monkey preoptic hypothalamus during thermoregulatory operant behavior

Unit activities of thermosensitive (TS) and non-TS neurons in the medial preoptic area (MPO) of the monkey were investigated during a high fixed-ratio (FR 12–30) bar press behavior to seek cool air (CT) in a warm environment. The monkey performed the task when ambient temperature (T a) was raised (35–43°C) and the animal was rewarded with a fall in T a (23–25°C). The population of neurons which changed the activity at least in one phase of CT was significantly higher among TS neurons (42 of 46) than among non-TS neurons (29 of 64). The most frequently observed responses were the sustained increase or decrease in activity during the bar press period and/or the cooling period. The bar press related activity was not a pure motor coupled response, but its magnitude was greatly modified by the strength of motivation of animals to seek cool air. The cooling phase-related activity was not a thermosensory response which simply reflects the level of skin temperature or its change. It was shown that the response was dependent upon the rewarding value of the cooling air. The results suggest that TS neurons in the MPO may be involved in the control of thermoregulatory cooling behavior.