The characteristics of the electrodermal activity during changes in the level of human wakefulness

The wake-drowsiness transition during the performance of a monotonous psychomotor test was studied using polygraphic recording, with particular emphasis on changes in the electrodermal activity (EDA) and occurrence of electrodermal reactions (EDR). It was found that decrease in wakefulness was accompanied by a drop of the EDA. The EDR gradually disappeared for several minutes and did not reappear without activation; their dependence on sex and individual features of a subject significantly increased. It is suggested that discrepancies in the experimental results of psychophysiological studies with EDA may be explained by an insufficient control of the subject's alertness throughout the experiment. Examples of such discrepancies are given: disagreement of sex differences in the EDA, differentiation between EDA-labile and EDA-stable persons, on a possibility of recording the "emotional" EDA from different parts of human body etc. The ways of reproducibility of the results are discussed including the recording of several wake-drowsiness transitions and better recognition of the EDR.     

Niacin skin-flush response and electrodermal activity in patients with schizophrenia and healthy controls

Patients with schizophrenia have in different studies shown reduced niacin sensitivity and lower electrodermal activity (EDA) after auditory stimulation. Peripheral mediation of prostaglandins may have a physiological role in both responses. This motivates study of both niacin response and electrodermal responding in the same patients with schizophrenia. Thirty patients with schizophrenia and 17 controls were investigated with EDA and thereafter given 200mg niacin orally with continuous assessment of skin temperature. The patients showed a delayed temperature increase after niacin ingestion (P=0.002) and a higher frequency of electrodermal non-responding (P<0.05). Response/non-response for niacin correlated with EDA response/non-response in the patient group (P=0.009). The niacin test revealed a slower vasodilation reaction in the patients. The association between response patterns for the niacin test and EDA suggests that a common aberration in skin physiology may be of importance for both reactions in schizophrenia.     

Personality and Electrodermal Response Lability: An Interpretation

Electrodermal response (EDR) lability is a psychophysiological trait reflecting stable individual differences in electrodermal activation as indexed by frequency measures of phasic EDR activity. There is no consistent evidence that EDR lability reflects dispositional or clinical anxiety. However, EDR lability appears to be related to individual differences in the overt expression of emotional and antagonistic impulses. Greater EDR lability is associated with a relatively undemonstrative and agreeable disposition, whereas greater EDR stability is associated with a relatively expressive and antagonistic disposition. The inverse relationship between EDR lability and the expression of emotional and antagonistic impulses suggests that EDR lability may reflect individual differences in the effortful control of such expression. This hypothesis is consistent with cognitive effort interpretations of phasic EDR activity, with evidence of the sensitivity of phasic EDR activity to capacity-demanding tasks, and with evidence of reduced spare capacity among EDR labile individuals under cognitive challenge. Individual differences in effortful self-control may explain the association of greater EDR lability with essential hypertension and greater EDR stability with forms of antisocial behavior.     

Instrumental conditioning of skin potential responses in curarized cats: non specific effects of a punishment procedure

This study evaluates the effects of a punishment paradigm upon electrodermal activity (EDA) in curarized cats. In ten experimental subjects, any skin potential response (SPR) exceeding threshold value was punished by an electric shock. Ten control subjects received an electric shock or an electric stimulation of the mesencephalic reticular formation unrelated to the EDA. The results show that: a) No significant modifications of EDA occurred in subjects characterized by low initial activity; b) The frequency of SPR significantly decreased in high activity subjects used both for the experiments and the controls. Therefore, this diminution, in experimental subjects, cannot be due to a learning process. Neither can it be related to level of curarization or to rate of artificial ventilation. It is suggested that this effect results from a non-specific cortical inhibitory mechanism acting on the reticular activating system. The results obtained in three decorticated cats submitted to a punishment procedure are in accordance with such an hypothesis. Consequently the existence of operant autonomic learning remains unproven.     

Comparison between monorhinal and birhinal olfactory stimulations in bilateral electrodermal recordings

The study of olfactory lateralization in human subjects has given rise to many publications, but the findings have often been contradictory. Most research used either birhinal or monorhinal stimulations, but rarely a comparison between these two types of olfactory input. The aim of this study was to investigate variations in psychophysiological measurements and test each side of the nose and binasal performances. This work used bilateral electrodermal recordings and compared the skin conductance responses (SCRs) for a pleasant odorant (isoamyl acetate) and an unpleasant odorant (triethylamine) in a suprathreshold concentration on 30 dextral subjects (16 females and 14 males). First, the results reported no differences between the two nostrils but differences in electrodermal activity (EDA) in relation to the odorant: 1) higher amplitude in response to unpleasant versus pleasant odorant; 2) no differences between monorhinal and birhinal stimulations for the unpleasant odour but higher amplitude in response to birhinal versus monorhinal for the pleasant odour. Second, the results showed constant bilateral differences in EDA recordings and are discussed in terms of hemispheric asymmetry activation.     

Amplitude,latency, and habituation of the electrodermal response to acoustic stimuli in the frog

The electrodermal response (EDR) of frogs to various acoustic stimuli was measured in the form of the skin potential response (SPR). There was no correlation between the polarity of the SPR and the intensity of the stimuli. When different frequencies were presented at the same intensity, the amplitude of the SPR to each was inversely proportional to the sound pressure at which that frequency just elicited an SPR. The amplitude of the sound-induced SPR increased monotonically with increasing sound pressure. The latency of the SPR decreased with increasing intensity of the acoustic stimulus. Acoustic stimuli repeated at intervals of 1 and 2 min elicited responses with progressively decreased amplitude and increased latency; with 4 min intervals there was little habituation. Fatigue participates to only a very slight extent in reducing the amplitude of the SPR and increasing its latency. The results are compared with the published data on frogs and mammals, including humans.     

Anticipatory Electrodermal Response as a Differentiating Somatic Marker Between Children with ADHD and Controls

Six children with Attention Deficit Hyperactivity Disorder (ADHD) and five control children between the ages of 9 and 11 years were administered an adapted version of the Iowa Gambling Task while measuring anticipatory electrodermal response (EDR). Anticipatory EDR measures were compared between groups. Results indicate that the ADHD group exhibited significantly lower autonomic reactivity to anticipated consequences, evidencing a neuropsychological profile similar to patients with lesions in the ventromedial prefrontal cortex.     

Skin responses to ultraviolet radiation: effects of constitutive pigmentation,sex, and ancestry

Constitutive skin pigmentation and skin responses to ultraviolet radiation were measured on a sample of volunteers (n=250) living in State College, PA, USA. The sample was composed of individuals of European American (n=190), Hispanic (n=45), and East Asian ancestry (n=15). Constitutive pigmentation was measured using the Adjusted Melanin Index (AMI), Erythemal Dose Response (EDR) was measured using the slope of a* at 24 h (Deltaa*), and Melanogenic Dose-Response (MDR) was measured using DeltaAM, the slope of AMI at 7 d. The relationships between constitutive skin pigmentation, EDR, MDR, sex, age, and ancestry were investigated. European Americans showed a lower constitutive pigmentation, had a significantly higher burn response (EDR), and had a significantly lower tanning response (MDR) than Hispanics and East Asians. No significant difference is seen between Hispanics and East Asians for either constitutive pigmentation or EDR. Constitutive pigmentation in females was slightly lower than in males in all three samples, but the difference was not significant. While no differences were observed in MDR between sexes, males had a stronger EDR than females regardless of population or constitutive pigmentation level, and this difference was significant in European Americans and Hispanics. We observed no age-related differences in any of the populations or measures investigated. We evaluated the relationship between constitutive pigmentation, EDR and MDR. There was a strong inverse correlation between constitutive pigmentation and EDR in the three samples (European Americans, R2=0.176, P < 0.001; Hispanics, R2=0.204, P=0.009; East Asians, R2=0.223, P=0.098) and a strong direct correlation between constitutive pigmentation and MDR in European Americans and Hispanics (European Americans, R2=0.094, P < 0.001; Hispanics, R2=0.164, P=0.012). In other words, persons with lower constitutive pigmentation both burn more and tan less than persons with higher pigmentation. However, after controlling for constitutive pigmentation, EDR and MDR were significantly correlated in European Americans (R2=0.041 P=0.006). Thus, the general observation that persons who burn more tan less is probable because of the common link that these two phenotypes have with constitutive skin pigmentation and, in fact, once pigmentation has been adjusted for, there is a positive correlation between tanning response and burning response in European Americans.     

Skin Responses to Ultraviolet Radiation: Effects of Constitutive Pigmentation,Sex, and Ancestry

Constitutive skin pigmentation and skin responses to ultraviolet radiation were measured on a sample of volunteers (n=250) living in State College, PA, USA. The sample was composed of individuals of European American (n=190), Hispanic (n=45), and East Asian ancestry (n=15). Constitutive pigmentation was measured using the Adjusted Melanin Index (AMI), Erythemal Dose Response (EDR) was measured using the slope of a* at 24 h (Δa*), and Melanogenic Dose–Response (MDR) was measured using ΔAM, the slope of AMI at 7 d. The relationships between constitutive skin pigmentation, EDR, MDR, sex, age, and ancestry were investigated. European Americans showed a lower constitutive pigmentation, had a significantly higher burn response (EDR), and had a significantly lower tanning response (MDR) than Hispanics and East Asians. No significant difference is seen between Hispanics and East Asians for either constitutive pigmentation or EDR. Constitutive pigmentation in females was slightly lower than in males in all three samples, but the difference was not significant. While no differences were observed in MDR between sexes, males had a stronger EDR than females regardless of population or constitutive pigmentation level, and this difference was significant in European Americans and Hispanics. We observed no age‐related differences in any of the populations or measures investigated. We evaluated the relationship between constitutive pigmentation, EDR and MDR. There was a strong inverse correlation between constitutive pigmentation and EDR in the three samples (European Americans, R²=0.176, P < 0.001; Hispanics, R²=0.204, P=0.009; East Asians, R²=0.223, P=0.098) and a strong direct correlation between constitutive pigmentation and MDR in European Americans and Hispanics (European Americans, R²=0.094, P < 0.001; Hispanics, R²=0.164, P=0.012). In other words, persons with lower constitutive pigmentation both burn more and tan less than persons with higher pigmentation. However, after controlling for constitutive pigmentation, EDR and MDR were significantly correlated in European Americans (R²=0.041 P=0.006). Thus, the general observation that persons who burn more tan less is probable because of the common link that these two phenotypes have with constitutive skin pigmentation and, in fact, once pigmentation has been adjusted for, there is a positive correlation between tanning response and burning response in European Americans.     

Sex differences, activation level, and bilateral electrodermal activity

The effects of the activation level and subject's sex on bilateral skin conductance measures were studied. Thirty right-handed subjects (15 males and 15 females) were exposed to three types of stimulus conditions: rest-period, verbal task and spatial task. Results showed that no relationship was observed between EDA asymmetry and the increase in the activation level induced by the verbal and the spatial tasks. Males showed both higher SCRs and greater frequency of responses on the left than on the right hand. The direction of electrodermal asymmetry remained constant regardless of the stimulus conditions. It was concluded that sex differences are important in the study of EDA asymmetry and that this asymmetry appeared to depend on peripheral variations.     

Influence of Short-Term Relaxation on the Organization of the Brain Electrical Activity of Young Schoolchildren in the State of Quiet Wakefulness

Relaxation-induced changes in characteristics of the functional state of the nervous system (EEG parameters and electrodermal resistance (EDR)) were studied in 30 schoolchildren aged 9–10 years. A multichannel EEG was recorded from the occipital, parietal, temporo-parieto-occipital, central, and frontal areas of both brain hemispheres in three test conditions: quiet wakefulness, R, and recovery of the initial state. Simultaneously, the EDR was monitored. EEG amplitude spectra and coherence were calculated. Prior to and after relaxation, a cognitive test to determine the extent of short-term auditory verbal memory was performed. While changes in the EDR were reversible, relaxation-induced changes in the EEG parameters persisted after relaxation in many subjects. Changes in EEG coherence between distant derivations were most stable. Since short-term auditory verbal memory improved after relaxation, the postrelaxation changes in the EEG parameters were considered to reflect positive changes arising in the brain function and increasing the efficiency of cognitive processes.     

The human thermal portrait and its relations with aerobic working capacity and the blood lactate level

In a study on 53 healthy male volunteers with the use of an infrared thermograph, data that the thermal portrait, i.e., skin temperature distribution, under the conditions of muscular rest and minimal chemical thermoregulation activation is related to the maximal aerobic capacity (r = + 0.6) and the lactate level after critical muscle load (r = −0.7) were obtained. A series of pilot experiments on six volunteers showed that acute regional cooling (by placing feet into ice-cold water for 1 min) led to temperature rise in some local areas of the breast and back skin and increase in oxygen uptake, pulmonary ventilation and the respiratory quotient. Simultaneously, the lactate level in peripheral blood was reduced. On the basis of these results, it was assumed that brown adipose tissue (BAT) activity influenced the thermal portrait formation in the case of environmental temperature below thermoneutral. This hypothesis makes it possible to explain a negative correlation between the skin temperature and the body mass index and a twofold increase in the oxygen uptake during acute cold exposure. Nevertheless, further investigations are necessary to clarify the physiological mechanisms underlying the significant correlation between skin temperatures at rest under thermoneutral conditions and the maximal aerobic capacity, anaerobic threshold and lactate accumulation after critical muscle load.     

Circadian rhythms of locomotor activity and temperature selection in sleepy lizards, <Emphasis Type="Italic">Tiliqua rugosa</Emphasis>

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.     

Analysis of physiological signals for recognition of boredom,pain, and surprise emotions

Background

The aim of the study was to examine the differences of boredom, pain, and surprise. In addition to that, it was conducted to propose approaches for emotion recognition based on physiological signals.

Methods

Three emotions, boredom, pain, and surprise, are induced through the presentation of emotional stimuli and electrocardiography (ECG), electrodermal activity (EDA), skin temperature (SKT), and photoplethysmography (PPG) as physiological signals are measured to collect a dataset from 217 participants when experiencing the emotions. Twenty-seven physiological features are extracted from the signals to classify the three emotions. The discriminant function analysis (DFA) as a statistical method, and five machine learning algorithms (linear discriminant analysis (LDA), classification and regression trees (CART), self-organizing map (SOM), Naïve Bayes algorithm, and support vector machine (SVM)) are used for classifying the emotions.

Results

The result shows that the difference of physiological responses among emotions is significant in heart rate (HR), skin conductance level (SCL), skin conductance response (SCR), mean skin temperature (meanSKT), blood volume pulse (BVP), and pulse transit time (PTT), and the highest recognition accuracy of 84.7 % is obtained by using DFA.

Conclusions

This study demonstrates the differences of boredom, pain, and surprise and the best emotion recognizer for the classification of the three emotions by using physiological signals.     

Thermal stimulation of exposed skin area influences behavioral thermoregulation in pigeons

Summary Pigeons were trained to work instrumentally for thermal reinforcement under ambient heat and cold loads. Facial or breast skin temperature was selectively altered by means of air-perfused thermodes. Facial stimulation with temperatures in the normally occurring range resulted in changes of instrumental response rate, accompanied by stimulus opposing deviations of core temperature (Fig. 5). Breast skin stimulations with the same stimulation amplitudes also affected behavioral thermoregulation, but without changing core temperature. Small temperature changes, as naturally occur at feathered breast skin, had no effect on response rate. Behavioral adjustments occurring within 15 s in response to altering either ambient load temperature or facial temperature locally (Fig. 6), support the hypothesis that the face represents a site driving short term behavioral adjustments to ambient disturbances.Abbreviations RF reinforcement(s) - T _a temporal mean of ambient temperature - T _load load temperature - T _c (colonic) core temperature - T _s skin temperature - T _s(v) ventral skin temperature - T _s(d) dorsal skin temperature - T _ax axilla temperature     

Incorporating neurophysiological concepts in mathematical thermoregulation models

Skin blood flow (SBF) is a key player in human thermoregulation during mild thermal challenges. Various numerical models of SBF regulation exist. However, none explicitly incorporates the neurophysiology of thermal reception. This study tested a new SBF model that is in line with experimental data on thermal reception and the neurophysiological pathways involved in thermoregulatory SBF control. Additionally, a numerical thermoregulation model was used as a platform to test the function of the neurophysiological SBF model for skin temperature simulation. The prediction-error of the SBF-model was quantified by root-mean-squared-residual (RMSR) between simulations and experimental measurement data. Measurement data consisted of SBF (abdomen, forearm, hand), core and skin temperature recordings of young males during three transient thermal challenges (1 development and 2 validation). Additionally, ThermoSEM, a thermoregulation model, was used to simulate body temperatures using the new neurophysiological SBF-model. The RMSR between simulated and measured mean skin temperature was used to validate the model. The neurophysiological model predicted SBF with an accuracy of RMSR?<?0.27. Tskin simulation results were within 0.37 °C of the measured mean skin temperature. This study shows that (1) thermal reception and neurophysiological pathways involved in thermoregulatory SBF control can be captured in a mathematical model, and (2) human thermoregulation models can be equipped with SBF control functions that are based on neurophysiology without loss of performance. The neurophysiological approach in modelling thermoregulation is favourable over engineering approaches because it is more in line with the underlying physiology.     

Quantitative noninvasive electrophysiological evaluation of the activity of the cutaneous division of the sympathetic nervous system.

The functional status of the cutaneous division of the orthosympathetic nervous system was indirectly and non-invasively assessed by monitoring the skin electrical relative resistance variations (SERV). The advantages of our recording system of second generation were (1) simultaneous recording on two or four channels of the evoked electrodermal response to psychic or to sensorial stimulus; (2) self-balancing system which allows the recording of the relative variation of the electric parameter, i.e. its variation with time; (3) precise determination of the amplitude (omega/s, mu F/s) of the evoked response; (4) reference of the latency time (LT) of the evoked response to the length of the anatomical pathway of the signal giving the autonomic conduction velocity (ACV). Decrease in diabetic autonomic neuropathy of both spontaneous and evoked electrodermal activities suggested their relationship with cutaneous sympathetic activity.     

Regulation of plant disease resistance, stress responses, cell death, and ethylene signaling in Arabidopsis by the EDR1 protein kinase

ENHANCED DISEASE RESISTANCE 1 (EDR1) encodes a CTR1-like kinase and was previously reported to function as a negative regulator of disease resistance and ethylene-induced senescence. Here, we report that the edr1 mutant displays enhanced stress responses and spontaneous necrotic lesions under drought conditions in the absence of pathogen, suggesting that EDR1 is also involved in stress response signaling and cell death regulation. Double mutant analysis revealed that these drought-induced phenotypes require salicylic acid but not ethylene signaling pathways. In addition, the edr1-mediated ethylene-induced senescence phenotype was suppressed by mutations in EIN2, but not by mutations in SID2, PAD4, EDS1, or NPR1, suggesting that EDR1 functions at a point of cross talk between ethylene and salicylic acid signaling that impinges on senescence and cell death. Two edr1-associated phenotypes, drought-induced growth inhibition and ethylene-induced senescence, were suppressed by mutations in ORE9, implicating ubiquitin-mediated protein degradation in the regulation of these phenotypes. However, the ore9 mutation did not suppress edr1-mediated enhanced disease resistance to powdery mildew or spontaneous lesions, indicating that these phenotypes are controlled by separate signaling pathways. To investigate the function of the EDR1 kinase domain, we expressed the C-terminal third of EDR1 in wild-type Columbia and edr1 backgrounds under the control of a dexamethasone-inducible promoter. Overexpression of the EDR1 kinase domain in an edr1 background had no obvious effect on edr1-associated phenotypes. However, overexpression of the EDR1 kinase domain in a wild-type Columbia background caused dominant negative phenotypes, including enhanced disease resistance to powdery mildew and enhanced ethylene-induced senescence; thus, the overexpressed EDR1 kinase domain alone does not exert EDR1 function, but rather negatively affects the function of native EDR1 protein.     

Investigating the Autonomic Nervous System Response to Anxiety in Children with Autism Spectrum Disorders

Assessment of anxiety symptoms in autism spectrum disorders (ASD) is a challenging task due to the symptom overlap between the two conditions as well as the difficulties in communication and awareness of emotions in ASD. This motivates the development of a physiological marker of anxiety in ASD that is independent of language and does not require observation of overt behaviour. In this study, we investigated the feasibility of using indicators of autonomic nervous system (ANS) activity for this purpose. Specially, the objectives of the study were to 1) examine whether or not anxiety causes significant measurable changes in indicators of ANS in an ASD population, and 2) characterize the pattern of these changes in ASD. We measured three physiological indicators of the autonomic nervous system response (heart rate, electrodermal activity, and skin temperature) during a baseline (movie watching) and anxiety condition (Stroop task) in a sample of typically developing children (n = 17) and children with ASD (n = 12). The anxiety condition caused significant changes in heart rate and electrodermal activity in both groups, however, a differential pattern of response was found between the two groups. In particular, the ASD group showed elevated heart rate during both baseline and anxiety conditions. Elevated and blunted phasic electrodermal activity were found in the ASD group during baseline and anxiety conditions, respectively. Finally, the ASD group did not show the typical decrease in skin temperature in response to anxiety. These results suggest that 1) signals of the autonomic nervous system may be used as indicators of anxiety in children with ASD, and 2) ASD may be associated with an atypical autonomic response to anxiety that is most consistent with sympathetic over-arousal and parasympathetic under-arousal.     

A cardiorespiratory classifier of voluntary and involuntary electrodermal activity

Background  

Electrodermal reactions (EDRs) can be attributed to many origins, including spontaneous fluctuations of electrodermal activity (EDA) and stimuli such as deep inspirations, voluntary mental activity and startling events. In fields that use EDA as a measure of psychophysiological state, the fact that EDRs may be elicited from many different stimuli is often ignored. This study attempts to classify observed EDRs as voluntary (i.e., generated from intentional respiratory or mental activity) or involuntary (i.e., generated from startling events or spontaneous electrodermal fluctuations).