The hypothesis of the nature of electrodermal reactions

Long-term studies of electrodermal activity (EDA) in the activation-relaxation cycles, including simultaneous recording of skin resistance and temperature, were conducted. The new facts observed (a rapid drop in conductance after electrodermal response (EDR), a frequent absence of a correlation between skin resistance and EDR frequency, the conditions for correlation between the dynamics of resistance and temperature) are difficult to explain within the framework of the most generally accepted hypothesis of the formation of all EDA components by the secretory region of the eccrine sweat glands. They testify in favor of the hypothesis of the existence of two systems of EDA regulation that are largely independent. According to the hypothesis, the thermoregulation function is mainly mediated by the continuous release of a secretion resulting in tonic changes in resistance. EDR occur in response to emotions and are associated with thermoregulation, but only slightly. They are determined by the properties of the excretory region of the gland. The phase of decrease in resistance is accompanied by narrowing of the ducts caused by myoepithelial cells on activation, possibly adrenergic, of the sympathetic nervous system.     

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.     

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.     

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.     

Dynamics of the Adolescent EEG Parameters with Changes in the CNS Functional State (Relaxation) Influenced by Rhythmic Acoustic Stimulation

Age-related specific features of the regulation of the CNS functional state (relaxation) were studied in adolescents between the ages of 14 and 15 years using 6-Hz rhythmic stimulation. The dynamics of the EEG findings (spectral power density, coherence functions) in the quiet wakefulness–relaxation–initial-state cycle was analyzed. The dynamics of the functional state was controlled by changes in the electrodermal resistance (EDR). The data showed that the studied group of adolescents was heterogeneous by the effectiveness of self-regulation: the majority was characterized by marked shifts whose distribution character was close to normal; the others, by mild EDR changes. It was shown that, with the use of rhythmic stimulation, relaxation shifts were more marked than those induced by common psychotherapeutic techniques. The basic relaxation changes in the EEG parameters are related to changes in the coherence function values, i.e., increases in its values, especially those of distant relations (with the focus) of significant connections in the frontal regions. The rate of the occurrence of relaxation changes in the coherence values is substantially higher in the low-frequency band (5 to 7 Hz) than in the EEG -band, constituting 20 to 50% in terms of different relations. The revealed specific features of the relaxation dynamics of the EEG parameters are analyzed in the age-related aspect. The influence of higher structures of the CNS and puberty-related rearrangements in the system of neuroendocrine regulation on the effectiveness of the regulatory function is discussed.     

Rhythmic Acoustic Stimulation as a Method for Regulating the Functional State of the CNS in Young Schoolchildren

The author studied the dynamics of EEG (spectral power density and coherence functions) and autonomic (electrodermal resistance, EDR) indices in young schoolchildren with changes in the functional state of the CNS caused by rhythmic sensory stimulation (acoustic signals with frequencies of 6 and 9 Hz). Both of these signals influenced the CNS and may be used to achieve relaxation. Their comparison demonstrated both similar postrelaxation shifts (increased coherence of distant connections) and frequency-specific phenomena (more numerous significant changes in the respective frequency ranges). Thus, the signal frequency determines the pattern of physiological shifts, influencing the relaxation quality. Low-frequency (6 Hz) stimulation caused more pronounced changes in the CNS, reflected in enhanced EDR, and a stronger increase in the short-term memory volume. The author discusses the frequency-specific neurophysiological mechanisms of the effect of stimulation on the functional state of the brain.     

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.     

Epileptiform activity in alcohol dependent patients and possibilities of its indirect measurement

Background

Alcohol dependence during withdrawal and also in abstinent period in many cases is related to reduced inhibitory functions and kindling that may appear in the form of psychosensory symptoms similar to temporal lobe epilepsy frequently in conditions of normal EEG and without seizures. Because temporal lobe epileptic activity tend to spread between hemispheres, it is possible to suppose that measures reflecting interhemispheric information transfer such as electrodermal activity (EDA) might be related to the psychosensory symptoms.

Methods and Findings

We have performed measurement of bilateral EDA, psychosensory symptoms (LSCL-33) and alcohol craving (ACQ) in 34 alcohol dependent patients and 32 healthy controls. The results in alcohol dependent patients show that during rest conditions the psychosensory symptoms (LSCL-33) are related to EDA transinformation (PTI) between left and right EDA records (Spearman r = 0.44, p<0.01).

Conclusions

The result may present potentially useful clinical finding suggesting a possibility to indirectly assess epileptiform changes in alcohol dependent patients.     

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.     

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.     

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.     

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.     

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).     

Relation of the antitumor activity of 4'-epidoxorubicin and cytogenetic disorders of tumor cells in experimental studies

Antitumor and cytogenetic activities of 4-epi-doxorubicin (EDR), an anthracycline antibiotic, were studied on female Wistar rats with transplantable ascitic ovary tumor (OT). It was shown that after a single administration in a dose of 3 mg/kg, EDR prolonged the average lifespan of the tumor-bearing rats by 213.4 per cent as compared to that in the controls. The maximum number of the aberrant cells in the bone marrow was observed 24 hours after injection of EDR. In 6 day it decreased to the control level. The maximum increase in the number of the OT aberrant cells was recorded 2 days after EDR injection and even in 10 days the number of the aberrant cells amounted to 20.2 +/- 1.3 per cent. It is suggestive of a high selective action of EDR and relation between the EDR antitumor activity and the disturbances in the chromosomal apparatus of the OT cells.     

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.     

Sex differences and bilateral electrodermal activity: a replication

The present study was aimed at replicating the results of a previous work on sex differences and electrodermal asymmetry from our laboratory (Román, et al. 1987). Skin conductance was bilaterally recorded in a sample of 44 dextral volunteers (22 males and 22 females) during a stimulus-free period, and the performance of two tasks (verbal and spatial). Subjects were grouped into two groups of right-hand and left-hand dominance in their electrodermal responses (EDRs) in accordance with their laterality coefficient scores at rest. During the tasks subjects appeared clearly differentiated by their lateralization in the magnitude and frequency of EDRs independently of gender: right-hand responders showed higher electrodermal activity on their right hand, while left-hand responders showed higher electrodermal activity on their left hand. Sex differences were not observed within each responsiveness pattern. The orientation of phasic electrodermal changes remained constant throughout the different conditions.     

Subclinical epileptiform process in patients with unipolar depression and its indirect psychophysiological manifestations

Background

According to recent clinical findings epileptiform activity in temporolimbic structures may cause depressive and other psychiatric symptoms that may occur independently of any seizure in patient''s history. In addition in these patients subclinical seizure-like activity with indirect clinical manifestations likely may occur in a form of various forms of cognitive, affective, memory, sensory, behavioral and somatic symptoms (the so-called complex partial seizure-like symptoms). A typical characteristic of epileptiform changes is increased neural synchrony related to spreading of epileptiform activity between hemispheres even in subclinical conditions i.e. without seizures. These findings suggest a hypothesis that measures reflecting a level of synchronization and information transfer between hemispheres could reflect spreading of epileptiform activity and might be related to complex partial seizure-like symptoms.

Methods and Findings

Suitable data for such analysis may provide various physiological signals reflecting brain laterality, as for example bilateral electrodermal activity (EDA) that is closely related to limbic modulation influences. With this purpose we have performed measurement and analysis of bilateral EDA and compared the results with psychometric measures of complex partial seizure-like symptoms, depression and actually experienced stress in 44 patients with unipolar depression and 35 healthy controls. The results in unipolar depressive patients show that during rest conditions the patients with higher level of complex partial seizure like symptoms (CPSI) display increased level of EDA transinformation (PTI) calculated between left and right EDA records (Spearman correlation between CPSI and PTI is r = 0.43, p = 0.004).

Conclusions

The result may present potentially useful clinical finding suggesting that increased EDA transinformation (PTI) could indirectly indicate increased neural synchrony as a possible indicator of epileptiform activity in unipolar depressive patients treated by serotoninergic antidepresants.     

The electrodermal indices of the subjective perception of performance errors during drowsy changes in consciousness

The study was aimed at searching for objective criteria of subject's perception of errors in performance due to drowsiness and estimating the time between the onset of errors and the moment of their awareness. Healthy subjects (n = 64) with the pronounced EEG alpha were examined under conditions without sleep deprivation. Experiments (n = 280) lasted for 40 min. During the experiments, the EEG, EOG, EDR, EKG, and button pressings were recorded and subject's reports were registered. The subjects were waken up after the onset of errors or 20 min after the beginning of the performance independently of errors. The error onset was shown to be preceded by the EEG "drowsy pattern" and decrease in the rate of spontaneous EDR. The performance reappearance after the error was accomplished by alpha-rhythm independently from error awareness. The interrogation of subjects after the error and activity revival demonstrated a correlation between the error subjective perception and appearance of the EDR. The interval between the error and the first following EDR (mean 10.1 s) was significantly (p < 0.001, t-test for dependent samples) shorter than the interval between the error and the last preceding EDR (mean 69.8 s). It is suggested that the subjective perception of an error is a significant endogenous stimulus, which evokes the orienting response and accompanying sympathetic activation.     

Chiral discrimination of 5,6-epoxy-3-dehydroretinal by aporetinochrome and cattle opsin

The combination of a racemic all-trans 5,6-epoxy-3-dehydroretinal (EDR) with aporetinochrome formed a mixture of two diastereomeric pigments. One of the diastereomeric pigments which contained the all-trans EDR with a negative circular dichroic (CD) band, hereafter called EDR(-)-chrome, has its visible absorption maximum around 438 nm, while the other pigment, called EDR(+)-chrome, has its maximum at 464 nm. These were substantiated by measuring the optical activities of the two EDR isomers which were extracted from a mixture of racemic all-trans EDR and a smaller amount of aporetinochrome following exposure to orange light (greater than 530 nm) that irradiates EDR(+)-chrome selectively. The extracted all-trans EDR had a negative CD band around 240 nm and the extracted 11-cis EDR had a positive band in that region with two negative bands on either side of the main band. In the case of both pigments, the effect of alkalinization on the increase of absorbance in the near-ultraviolet and the decrease of absorbance in the visible region was proportionate, qualitatively, to that on the positive CD intensities in both regions. These results suggest that the chromophore EDR in each pigment binds to the same binding site via a Schiff base. The EDR(+)-chrome exhibited properties similar to those of retinochrome, but EDR(-)-chrome showed some different properties, i.e. its formation rate was slower than that of the former one and its absorption band in the near-ultraviolet appeared even at neutral pH. Moreover, by exposing EDR(-)-chrome to yellow light (greater than 480 nm), only a part of its prosthetic all-trans EDR was isomerized and resulted in the formation of 11-cis and 13-cis isomers. This variation in photoisomerizing activity was supposed to be due to the difference in conformation of the side chain between EDR(+) and EDR(-) in aporetinochrome. Combination of 11-cis EDR with cattle opsin was also shown to result in the formation of two diastereomeric pigments. The absorption maxima of the diastereomers containing 11-cis EDR(+) and EDR(-) were at about 446 and 474 nm, respectively.     

Diurnal Emotional States Impact the Sleep Course

Background

Diurnal emotional experiences seem to affect several characteristics of sleep architecture. However, this influence remains unclear, especially for positive emotions. In addition, electrodermal activity (EDA), a sympathetic robust indicator of emotional arousal, differs depending on the sleep stage. The present research has a double aim: to identify the specific effects of pre-sleep emotional states on the architecture of the subsequent sleep period; to relate such states to the sympathetic activation during the same sleep period.

Methods

Twelve healthy volunteers (20.1 ± 1.0 yo.) participated in the experiment and each one slept 9 nights at the laboratory, divided into 3 sessions, one per week. Each session was organized over three nights. A reference night, allowing baseline pre-sleep and sleep recordings, preceded an experimental night before which participants watched a negative, neutral, or positive movie. The third and last night was devoted to analyzing the potential recovery or persistence of emotional effects induced before the experimental night. Standard polysomnography and EDA were recorded during all the nights.

Results

Firstly, we found that experimental pre-sleep emotional induction increased the Rapid Eye Movement (REM) sleep rate following both negative and positive movies. While this increase was spread over the whole night for positive induction, it was limited to the second half of the sleep period for negative induction. Secondly, the valence of the pre-sleep movie also impacted the sympathetic activation during Non-REM stage 3 sleep, which increased after negative induction and decreased after positive induction.

Conclusion

Pre-sleep controlled emotional states impacted the subsequent REM sleep rate and modulated the sympathetic activity during the sleep period. The outcomes of this study offer interesting perspectives related to the effect of diurnal emotional influences on sleep regulation and open new avenues for potential practices designed to alleviate sleep disturbances.