Publication recommendations for electrodermal measurements

When electrodermal activity (EDA) recordings are controlled for artifacts, i.e., electrodermal reactions [EDRs] elicited by breathing irregularities, several problems arise. For example, respiration is difficult to evaluate because there are no clear-cut criteria for its values, e.g., wave form, depth. Furthermore, respiration and EDA are rather complexly intertwined, and there is no established or standardized method for evaluation. Especially when subjects are not stimulated, i.e., when nonspecific EDRs are taken, EDR recordings elicited by irregular breathing may overestimate the subject's arousal and bias any given research question. Moreover, incidences of concurrent consecutive EDRs and changes in respiratory activity may encourage multicausal interpretation due to both signals' having a common central causation. To circumvent such problems, we developed a method which provides rule-based guidelines to identify potential artifacts. Two experiments (N = 14 and N = 12) were conducted to test the accuracy of the judgments of three independent raters. The reliability coefficients for the number of electrodermal reactions and the sum of their amplitudes yielded satisfactory coefficients of convergence for each individual experiment (.87 and .82 in Exp. 1 vs .94 and .95 in Exp. 2) as well as for the two experiments combined (.92 and .91).

Background. Functional magnetic resonance imaging (fMRI) appears to be useful for investigating motor recovery after stroke. Some of the potential confounders of brain activation studies, however, could be mitigated through complementary physiological monitoring. Objective. To investigate a sensorimotor fMRI battery that included simultaneous measurement of electrodermal activity in subjects with hemiparetic stroke to provide a measure related to the sense of effort during motor performance. Methods. Bilateral hand and ankle tasks were performed by 6 patients with stroke (2 subacute, 4 chronic) during imaging with blood oxygen level-dependent (BOLD) fMRI using an event-related design. BOLD percent changes, peak activation, and laterality index values were calculated in the sensorimotor cortex. Electrodermal recordings were made concurrently and used as a regressor. Results. Sensorimotor BOLD time series and percent change values provided evidence of an intact motor network in each of these well-recovered patients. During tasks involving the hemiparetic limb, electrodermal activity changes were variable in amplitude, and electrodermal activity time-series data showed significant correlations with fMRI in 3 of 6 patients. No such correlations were observed for control tasks involving the unaffected lower limb. Conclusions. Electrodermal activity activation maps implicated the contralesional over the ipsilesional hemisphere, supporting the notion that stroke patients may require higher order motor processing to perform simple tasks. Electrodermal activity recordings may be useful as a physiological marker of differences in effort required during movements of a subject's hemiparetic compared with the unaffected limb during fMRI studies.

Electrodermal activity (EDA) is defined as a general term for all electrical behaviors in the skin, encompassing all active and passive electrical properties that can be traced back to the skin and its appendages. EDA measurements can be impacted by various factors and conditions. A factor of effect on EDA recordings, which has not been investigated before is the gender-related differences in the effects of skin hydration on EDA signals. Hence, this study aimed to study gender-related differences in the EDA parameters under conditions of skin hydration. 30 males and 30 females participated in this study under two different conditional (normal and hydration) experiments. Three EDA parameters (tonic and phasic components) were recorded from both groups. In the hydration experiment, 0.2 gram of 0.5% KCI in a 2% agar jelly was applied to the skin of all participants to moisturize their skin. The data from both experiments were analyzed to investigate gender-related differences in the effects of skin hydration on EDA measurements. It was found that EDA measurements, in particular the tonic component were not influenced by gender-related differences under hydration conditions. However, some significant (p<0.05) differences were observed between males and females in certain phasic parameters in response to specific stimuli. This study suggests that skin hydration does not contribute to gender-related differences in EDA recordings. These results are probably important in EDA investigations and applications.

Fluctuations in electrodermal activity reveal variations in single trial brain responses to painful laser stimuli — A fMRI/EEG study

Objective. Electrodermal activity (EDA) is a reliable indicator for variations in the skin electrical properties attributed to sympathetic nerve system activity. EDA recordings can be influenced by various internal and external factors including environmental ones. Ambient temperature can be considered as one of the possible factors which might influence EDA recordings. Hence, this study aimed to precisely investigate influence of ambient temperature on tonic and phasic EDA components by employing a new EDA measurement technique, which depends on simultaneously recording of several EDA parameters. Approach. Tonic and phasic EDA components during three different ambient temperature levels were recorded from 36 healthy participants. In addition, for evoking electrodermal responses, participants were exposed to cognitive, visual and breathing external stimuli. Main results. Significant effects of temperature on tonic skin conductance (SC), skin susceptance (SS) and skin potential (SP) were obtained, whereas such significant effects were not observed with phasic SC, SS and SP. Tonic EDA parameters were increased as a function of temperature, but changes in phasic component were fluctuating. Significance. This should mean that, keeping recording of tonic EDA component in normal room temperature is highly crucial, but for recording or analysis of phasic component it is not important as they are more robust in this context. This is important in applications of EDA instruments, particularly in wearable devices where environmental temperature typically cannot be controlled.

Daytime and nighttime patterns affect the dynamic modulation of brain and body functions and influence the autonomic nervous system response to seizures. Therefore, we aimed to evaluate 24-hour patterns of electrodermal activity (EDA) in patients with and without seizures. We included pediatric patients with (a) seizures (SZ), including focal impaired awareness seizures (FIAS) or generalized tonic-clonic seizures (GTCS), (b) no seizures and normal electroencephalography (NEEG), or (c) no seizures but epileptiform activity in the EEG (EA) during vEEG monitoring. Patients wore a device that continuously recorded EDA and temperature (TEMP). EDA levels, EDA spectral power, and TEMP levels were analyzed. To investigate 24-hour patterns, we performed a nonlinear mixed-effects model analysis. Relative mean pre-ictal (-30min to seizure onset) and post-ictal (I: 30min after seizure offset; II: 30 to 60min after seizure offset) values were compared for SZ subgroups. We included 119 patients (40 SZ, 17 NEEG, 62 EA). EDA level and power group-specific models (SZ, NEEG, EA) (h=1; P<.01) were superior to the all-patient cohort model. Fifty-nine seizures were analyzed. Pre-ictal EDA values were lower than respective 24-hour modulated SZ group values. Post hoc comparisons following the period-by-seizure type interaction (EDA level: =18.50; P<.001, and power: =6.73; P=.035) revealed that EDA levels were higher in the post-ictal period I for FIAS and GTCS and in post-ictal period II for GTCS only compared to the pre-ictal period. Continuously monitored EDA shows a pattern of change over 24 hours. Curve amplitudes in patients with recorded seizures were lower as compared to patients who did not exhibit seizures during the recording period. Sympathetic skin responses were greater and more prolonged in GTCS compared to FIAS. EDA recordings from wearable devices offer a noninvasive tool to continuously monitor sympathetic activity with potential applications for seizure detection, prediction, and potentially sudden unexpected death in epilepsy (SUDEP) risk estimation.

Measuring electrodermal activity (EDA) during fMRI is an effective means of studying the influence of task-related arousal, inferred from autonomic nervous system activity, on brain activation patterns. The goals of this study were: (1) to measure reliable EDA from healthy individuals during fMRI involving an effortful unilateral motor task, (2) to explore how EDA recordings can be used to augment fMRI data analysis. In addition to conventional hemodynamic modeling, skin conductance time series data were used as model waveforms to generate activation images from fMRI data. Activations from the EDA model produced significantly different brain regions from those obtained with a standard hemodynamic model, primarily in the insula and cingulate cortices. Onsets of the EDA changes were synchronous with the hemodynamic model, but EDA data showed additional transient features, such as a decrease in amplitude with time, and helped to provide behavioral evidence suggesting task difficulty decreased with movement repetition. Univariate statistics also confirmed that several brain regions showed early versus late session effects. Partial least squares (PLS) multivariate analysis of EDA and fMRI data provided complimentary, additional insight on how the motor network varied over the course of a single fMRI session. Brain regions identified in this manner included the insula, cingulate gyrus, pre- and postcentral gyri, putamen and parietal cortices. These results suggest that recording EDA during motor fMRI experiments provides complementary information that can be used to improve the fMRI analysis, particularly when behavioral or task effects are difficult to model a priori.

IntroductionAdaptive and successful emotion regulation, the ability to flexibly exert voluntary control over emotional experience and the ensuing behavior, is vital for optimal daily functioning and good mental health. In clinical settings, pharmacological and psychological interventions are widely employed to modify pathological emotion processing and ameliorate its deleterious consequences.MethodsIn this study, we investigated the acute effects of single-dose escitalopram on the induction and regulation of fear and disgust in healthy subjects. Furthermore, we compared these pharmacological effects with psychological emotion regulation that utilized a cognitive strategy with reappraisal. Emotion induction and regulation tasks were performed before and 4 h after ingestion of placebo or 10 mg escitalopram in a randomized, double-blind design. The International Affective Picture System (IAPS) was used as a source of images, with threat-related pictures selected for fear and disease and contamination-related pictures for disgust. Behavioral data, electrodermal activity (EDA), and functional near-infrared spectroscopy (fNIRS) recordings were collected.ResultsEscitalopram significantly reduced emotion intensity for both fear and disgust during emotion induction, albeit with differing electrodermal and hemodynamic activity patterns for the two negative emotions. At rest, i.e., in the absence of emotive stimuli, escitalopram increased sympathetic activity during the fear but not during the disgust experiments. For both fear and disgust, emotion regulation with reappraisal was more effective in reducing emotion intensity compared to pharmacological intervention with escitalopram or placebo.DiscussionWe concluded that emotion regulation with reappraisal and acute administration of escitalopram, but not placebo, reduce emotion intensity for both fear and disgust, with cognitive regulation being significantly more efficient compared to pharmacological regulation under the conditions of this study. Results from the fNIRS and EDA recordings support the concept of differential mechanisms of emotion regulation that could be emotion-specific.

This chapter reviews those studies conducted to date which have attempted to use brain imaging techniques to help identify the neuroanatomical and neurophysiological basis of skin conductance (SC) activity in humans. Methodological issues in the use of brain imaging as applied to electrodermal activity will be identified, and methodological issues in the recording of electrodermal activity will also be discussed in the context of findings from imaging studies. The potential value of using cluster analysis to seek categorical as opposed to continuous relationships between imaging and SC variables will be illustrated in a study which also attempts to demonstrate how more basic science research into brain mechanisms underlying SC activity can importantly inform clinical issues. Finally, conceptual and methodological issues in brain imaging - SC research will be discussed, and recommendations for future research in this area will be made. Because most studies have focussed on orienting activity, the focus of this review will be specifically on SC orienting.

The aim of this study was to assess the potential of electrodermal activity (EDA) as a diagnostic tool for preoperative evaluation in hyperhidrosis patients. EDA levels and patterns in different skin areas were investigated before and after endoscopic thoracic sympathicotomy (ETS) and was compared to healthy subjects. Thirty-seven patients underwent two days of measurements before and after the operation. Twenty-five (67.5%) of the patients also had a third measurement after six months. Non-invasive EDA measurements, involving skin conductance, were sampled from five different skin areas while patients were at rest in supine and sitting positions or when subjected to stimuli such as deep inspirations, mental challenge, and exposure to a sudden loud sound. Prior to the operation, hyperhidrosis patients showed higher spontaneous palm EDA variations at rest and stronger responses to stimuli compared to healthy subjects. Patients with facial blushing/hyperhidrosis or combined facial/palmar hyperhidrosis showed minimal spontaneous activity or responses, particularly during mental challenge and sound stimulus. Notably, palm EDA response was abolished shortly following sympathicotomy, although a minor response was observed after six months. Minimal EDA responses were also observed in the back and abdomen postoperatively. Hyperhidrosis patients showed stronger EDA response to stimuli compared to healthy subjects. Sympathicotomy resulted in the complete elimination of palm EDA responses, gradually returning to a limited extent after six months. These findings suggest that EDA recordings could be utilized in preoperative assessment of hyperhidrosis patients.

Electrodermal Activity (EDA) is a measure of skin conductance that reflects autonomic nervous system activity, offering insight into stress, emotional regulation, and autonomic arousals. This study investigates EDA fluctuations and sleep storms in older patients (≥50 years) with epilepsy, a population that has been underrepresented in previous research. We analyzed concurrent EEG and EDA recordings from 18 patients with 31 recording samples to characterize EDA events, particularly their distribution across sleep stages and quadrants of the night. Our findings reveal that Electrodermal Responses predominantly occur during N2 sleep, likely due to an age-related reduction in N3 duration. Contrary to prior reports of reduced EDA activity in REM sleep, we observed autonomic arousals during REM, suggesting activation of the central autonomic network during this sleep stage as well. Sleep storms showed variations depending on both sleep stage and time of night. Sleep storms were found to span multiple sleep stages, most commonly originating in N2, followed by REM and N1, with longer durations when originating earlier in the night. These results highlight the potential of EDA as a biomarker for sleep physiology and autonomic regulation in aging and epilepsy. Future studies should explore its implications for neurological health, cognitive function, and sleep quality assessment.Clinical Relevance- This work enhances our understanding of autonomic arousals during sleep in older adults with epilepsy, offering potential biomarkers for sleep quality assessment and neurological health monitoring.

Electrodermal activity (EDA) is traditionally taken from locations like the fingers, palms, or even the sole of the foot. These areas provide ideal signals but are easily corrupted by movement, limiting the practical acquisition of the signal during most activities. The torso could potentially offer an alternative location for EDA recording that negates the effect of such movements while preserving the information the signal holds. In this work, we collected EDA recordings from 10 subjects across five different locations (finger, sternum, lower pectoralis, hip, spine) while they were exposed to cognitive and physical stressors (Stroop task and cold pressor task respectively). Several EDA indices were derived from the EDA corresponding to each task and compared across all the locations using the finger data as reference. We found significant differences between stressor and baseline for the pectoral location when observing the time-varying index of sympathetic activity (TVSymp), in addition to the spine location when observing the spectral index of sympathetic activity based on EDA (Sympn). This corresponds with similar activation of the same indices captured by the fingers. Low correlation was found between locations for each metric. Additional work modifying subject hydration, electrode type, and signal filtering is required to identify an ideal torso location for EDA.

Efficient wavelet-based artifact removal for electrodermal activity in real-world applications

We propose the use of the convex optimization-based EDA (cvxEDA) framework to automatically characterize the force and velocity of caressing stimuli through the analysis of the electrodermal activity (EDA). CvxEDA, in fact, solves a convex optimization problem that always guarantees the globally optimal solution. We show that this approach is especially suitable for the implementation in wearable monitoring systems, being more computationally efficient than a widely used EDA processing algorithm. In addition, it ensures low-memory consumption, due to a sparse representation of the EDA phasic components. EDA recordings were gathered from 32 healthy subjects (16 females) who participated in an experiment where a fabric-based wearable haptic system conveyed them caress-like stimuli by means of two motors. Six types of stimuli (combining three levels of velocity and two of force) were randomly administered over time. Performance was evaluated in terms of execution time of the algorithm, memory usage, and statistical significance in discerning the affective stimuli along force and velocity dimensions. Experimental results revealed good performance of cvxEDA model for all of the considered metrics.

Electrodermal activity (EDA) is a well-established psychophysiological measurement for research and clinical approaches. Males and females often display different physiological responses to stimuli, which can be detected by EDA recordings. Using a new method to measure skin conductance (SC), skin potential (SP) and skin susceptance (SS) simultaneously at the same electrode, these differences were investigated. SC, SP, and SS were recorded from 60 participants during relaxation and stress. It was found that both tonic and phasic EDA parameters indicated gender differences. In addition, females displayed greater tonic and phasic EDA parameters (except for skin potential responses (SPRs)) than males under both relaxation and conditions of stimulation (stress). However, these results were not statistically significant (p &gt; 0.05). This suggests that it is perhaps important to consider gender or at least note type of gender in EDA researches, but this cannot be generalized to clinical approaches.