Skin Conductance Response Magnitude Research Articles

Sympathetic nervous system activity and pain-related response indexed by electrodermal activity during the earliest postnatal life in healthy term neonates.

Sympathetic nervous system (SNS) undergoes a prolonged period of fetal and neonatal development and maturation during which is vulnerable to a variety of influences (e.g. painful experiences). Thus, we aimed to evaluate SNS activity at rest and in response to stressful stimulus (pain) within the earliest postnatal life in healthy term neonates using electrodermal activity (EDA) measures. In twenty eutrophic healthy term neonates EDA was recorded within the first two hours after birth (measurement 1 - M1) and 72 h after birth (measurement 2 - M2) at rest and in response to pain (M1 - intramuscular K vitamin administration; M2 - heel stick). Evaluated parameters were skin conductance level (SCL), non-specific skin conductance responses (NS.SCRs), skin SCL 10 s before pain stimulus (SCL_10 before pain), skin conductance response (SCR) peak after pain stimulus, SCL 10 s after pain stimulus (SCL_10 after pain), SCR magnitude, latency, SCR rise/decline time, SCR half recovery time. SCL was significantly decreased at rest during M2 compared to M1 (p=0.010). SCL_10 before pain, SCR peak after pain, and SCL_10 after pain stimulus were significantly decreased in M2 compared to M1 (p=0.014, p=0.020, p=0.011, respectively). SCL was significantly decreased and NS.SCRs were significantly higher in the recovery period after the pain stimulus during M2 compared to M1 (p=0.015, p=0.032, respectively). Our results indicate EDA parameters sensitive to detect sympathetic changes during the earliest postnatal life reflecting its potential in early diagnosis of the autonomic maturation - linked pathological states in neonates.

Filtering and model-based analysis independently improve skin-conductance response measures in the fMRI environment: Validation in a sample of women with PTSD

Numerous methods exist for the pre-processing and analysis of skin-conductance response (SCR) data, but there is incomplete consensus on suitability and implementation, particularly with regard to signal filtering in conventional peak score (PS) analysis. This is particularly relevant when SCRs are measured during fMRI, which introduces additional noise and signal variability. Using SCR-fMRI data (n = 65 women) from a fear conditioning experiment, we compare the impact of three nested data processing methods on analysis using conventional PS as well as psychophysiological modeling. To evaluate the different methods, we quantify effect size to recover a benchmark contrast of interest, namely, discriminating SCR magnitude to a conditioned stimulus (CS+) relative to a CS not followed by reinforcement (CS-). Findings suggest that low-pass filtering reduces PS sensitivity (Δd = −20%), while band-pass filtering improves PS sensitivity (Δd = +27%). We also replicate previous findings that a psychophysiological modeling approach yields superior sensitivity to detect contrasts of interest than even the most sensitive PS method (Δd = +110%). Furthermore, we present preliminary evidence that filtering differences may account for a portion of exclusions made on commonly applied metrics, such as below zero discrimination. Despite some limitations of our sample and experimental design, it appears that SCR processing pipelines that include band-pass filtering, ideally with model-based SCR quantification, may increase the validity of SCR response measures, maximize research productivity, and decrease sampling bias by reducing data exclusion.

Anticipatory Threat Responding: Associations With Anxiety, Development, and Brain Structure

BackgroundWhile translational theories link neurodevelopmental changes in threat learning to pathological anxiety, findings from studies in patients inconsistently support these theories. This inconsistency may reflect difficulties in studying large patient samples with wide age ranges using consistent methods. A dearth of imaging data in patients further limits translational advances. We address these gaps through a psychophysiology and structural brain imaging study in a large sample of patients across the lifespan. MethodsA total of 351 participants (8–50 years of age; 209 female subjects; 195 healthy participants and 156 medication-free, treatment-seeking patients with anxiety) completed a differential threat conditioning and extinction paradigm that has been validated in pediatric and adult populations. Skin conductance response indexed psychophysiological response to conditioned (CS+, CS−) and unconditioned threat stimuli. Structural magnetic resonance imaging data were available for 250 participants. Analyses tested anxiety and age associations with psychophysiological response in addition to associations between psychophysiology and brain structure. ResultsRegardless of age, patients and healthy comparison subjects demonstrated comparable differential threat conditioning and extinction. The magnitude of skin conductance response to both conditioned stimulus types differentiated patients from comparison subjects and covaried with dorsal prefrontal cortical thickness; structure–response associations were moderated by anxiety and age in several regions. Unconditioned responding was unrelated to anxiety and brain structure. ConclusionsRather than impaired threat learning, pathological anxiety involves heightened skin conductance response to potential but not immediately present threats; this anxiety-related potentiation of anticipatory responding also relates to variation in brain structure. These findings inform theoretical considerations by highlighting anticipatory response to potential threat in anxiety.

The children of Superstorm Sandy: Maternal prenatal depression blunts offspring electrodermal activity

We set out to examine the relations between prenatal exposure to the natural disaster Superstorm Sandy, maternal depression, and offspring electrodermal activity (EDA). EDA was measured via skin conductance response (SCR) magnitude in 198 children (M = 42.54 months, SD = 12.76) during a startle paradigm. In keeping with prior research, we expected prenatal depression to be associated with hyporeactive EDA and prenatal stress to be associated with hyperreactive EDA. SCR magnitude was lower in children prenatally exposed to depression alone, when compared to Superstorm Sandy, and controls. SCR magnitude of children prenatally exposed to both maternal depression and the storm was lower than that of all other groups. Our results emphasize the influence of maternal prenatal mental health, support targeted risk assessment for children who experienced an adverse prenatal environment, and highlight the need for a deeper understanding of the interactions between maternal mood and stress on the developing child.

Out with the old and in with the new: The role of intolerance of uncertainty in reversal of threat and safety

Intolerance of uncertainty (IU) is associated with difficulty in updating contingencies from threatening to safe during extinction learning. However, it is unknown whether high IU individuals have difficulty (1) generally with updating threat to safe associations when contingencies change or (2) specifically with updating threat to safe associations during extinction learning, where direct threat is omitted. To address this question, we recorded IU, expectancy ratings, and skin conductance in 44 healthy participants during an associative learning paradigm, where threat and safety contingencies were reversed. During acquisition and reversal, we observed larger skin conductance response (SCR) magnitude and expectancy ratings for threat versus safety cues. However, during reversal, higher IU was associated with larger SCR magnitude to new threat versus new safety cues, compared with lower IU. These results were specific to IU-related variance, over shared variance with trait anxiety (State-Trait Anxiety Inventory, Trait Version). Overall, these findings suggest that individuals high in IU are able to reverse threat and safety associations in the presence of direct threat. Such findings help us understand the recently revealed link between IU and threat extinction, where direct threat is absent. Moreover, these findings highlight the potential relevance of IU in clinical intervention and treatment for anxiety disorders.

Using a Polygraph System for Evaluation of the Social Desirability Response Bias in Self-Report Measures of Aggression.

Empirical evidence suggests that respondents systematically overreport socially desirable behaviors and systematically underreport socially undesirable behaviors. This "social desirability response bias (SDRB)" presents significant challenges for research that relies on self-report measures to assess behaviors that adhere to or violate social norms. The present study used a state-of-the-art polygraph system to examine SDRB in widely used aggression questionnaires, including the Buss-Perry Aggression Questionnaire-Short Form, the Indirect Aggression subscale of the Aggression Questionnaire by Western Psychological Services, and the Reactive-Proactive Questionnaire. Sixteen college students with no criminal record, no known prior history of aggressive behavior, and no reported drug abuse, responded to verbally administered forms of the instruments. Indirect aggression items produced the largest, statistically significant physiological response across the sampled channels. The magnitude of this response was negatively and significantly correlated with the self-report ratings of the frequency of such behaviors. The mean separation between physiological (skin conductance) and self-report responses for indirect aggression remained significant and consistent with correlational analyses when both types of responses were converted to the same scale and compared directly. Finally, the relative magnitude of skin conductance response for items assessing indirect aggression was significantly greater than the relative magnitude of skin conductance response for direct aggression. Overall, the study suggests that the use of automated state-of-the art polygraph systems may potentially identify sensitive items on self-report instruments where social responsibility response bias is possible. Implications for the use of this procedure with such instruments are discussed.

The interaction of BDNF Val66Met, PTSD, and child abuse on psychophysiological reactivity and HPA axis function in a sample of Gulf War Veterans

IntroductionWhile the BDNF Val66Met polymorphism has been linked to various psychological disorders, limited focus has been on its relationship to posttraumatic stress disorder (PTSD) and early traumas such as child abuse. Therefore, we assessed whether Val66Met was associated with fear potentiated psychophysiological response and HPA axis dysfunction and whether PTSD status or child abuse history moderated these outcomes in a sample of Veterans. Methods226 and 173 participants engaged in a fear potentiated acoustic startle paradigm and a dexamethasone suppression test (DST) respectively. Fear conditions included no, ambiguous, and high threat conditions. Psychophysiological response measures included electromyogram (EMG), skin conductance response (SCR), and heart rate. The Clinician Administered PTSD Scale (CAPS) and the Trauma History Questionnaire (THQ) were used to assess PTSD status and child abuse history respectively. ResultsMet allele carriers exhibited greater SCR magnitudes in the no and ambiguous threat conditions (p < 0.01 and p < 0.05 respectively). Met carriers with PTSD exhibited greater physiological response magnitudes in the ambiguous (SCR, p < 0.001) and high threat conditions (SCR and heart rate, both p ≤ 0.005). Met carrier survivors of child abuse exhibited blunted heart rate magnitudes in the high threat condition (p < 0.01). Met allele carries with PTSD also exhibited greater percent cortisol suppression (p < 0.005). LimitationsLimitations included small sample size and the cross-sectional nature of the data. ConclusionsThe Val66met may impact PTSD susceptibility differentially via enhanced threat sensitivity and HPA axis dysregulation. Child abuse may moderate Val66Met's impact on threat reactivity. Future research should explore how neuronal mechanisms might mediate this risk.

Psychophysiological responses to auditory change.

A comprehensive characterization of autonomic and somatic responding within the auditory domain is currently lacking. We studied whether simple types of auditory change that occur frequently during music listening could elicit measurable changes in heart rate, skin conductance, respiration rate, and facial motor activity. Participants heard a rhythmically isochronous sequence consisting of a repeated standard tone, followed by a repeated target tone that changed in pitch, timbre, duration, intensity, or tempo, or that deviated momentarily from rhythmic isochrony. Changes in all parameters produced increases in heart rate. Skin conductance response magnitude was affected by changes in timbre, intensity, and tempo. Respiratory rate was sensitive to deviations from isochrony. Our findings suggest that music researchers interpreting physiological responses as emotional indices should consider acoustic factors that may influence physiology in the absence of induced emotions.

An Arousal Effect of Colors Saturation

Abstract. The purpose of the experiment was to test the relationship between attributes of color, self-rated arousal, and autonomic reactions to color stimuli. Sixteen colored backgrounds of different hue, saturation, and brightness were each viewed by 64 subjects (females, Mage = 22.48) while skin conductance responses (SCRs) were recorded. Subjective judgments relating to pleasantness (valence) and arousal were also measured. Results show that among color attributes only saturation had an effect on SCR magnitude, F(1, 63) = 6.31, p &lt; .05, ηG2 = .01. There was also significant correlation, r(14) = .64, p &lt; .01, between aggregated SCR magnitude and arousal ratings. It confirms that SCR could be used as a marker of phasic arousal even in response to the abstract, devoid of content stimuli. Saturation seems to be the main property connected with color’s ability to elicit orienting response. More saturated stimuli are better in capturing attention regardless of hue, thus suggesting that at the first stage of color perception, color intensity is more important than qualitative properties. Such results clarify some incoherent findings known from previous studies on psychophysiological responses to color stimuli.

Dissociable roles for hippocampal and amygdalar volume in human fear conditioning.

Fear conditioning is a basic learning process which involves the association of a formerly neutral conditioned stimulus (CS) with a biologically relevant aversive unconditioned stimulus (US). Previous studies conducted in brain-lesioned patients have shown that while the acquisition of autonomic fear responses requires an intact amygdala, a spared hippocampus is necessary for the development of the CS-US contingency awareness. Although these data have been supported by studies using functional neuroimaging techniques in healthy people, attempts to extend these findings to the morphological aspects of amygdala and hippocampus are missing. Here we tested the hypothesis that amygdalar and hippocampal volumes play dissociable roles in determining autonomic responses and contingency awareness during fear conditioning. Fifty-two healthy individuals (mean age 21.83) underwent high-resolution magnetic resonance imaging. We used a differential delay fear conditioning paradigm while assessing skin conductance responses (SCRs), subjective ratings of CS-US contingency, as well as emotional valence and perceived arousal. Left amygdalar volume significantly predicted the magnitude of differential SCRs during fear acquisition, but had no impact on contingency learning. Conversely, bilateral hippocampal volumes were significantly related to contingency ratings, but not to SCRs. Moreover, left amygdalar volume predicted SCRs to the reinforced CS alone, but not those elicited by the US. Our findings bridge the gap between previous lesion and functional imaging studies, by showing that amygdalar and hippocampal volumes differentially modulate the acquisition of conditioned fear. Further, our results reveal that the morphology of these limbic structures moderate learning and memory already in healthy persons.

Psychophysiological Response to Acoustic Intensity Change in a Musical Chord

This paper investigates psychological and psychophysiological components of arousal and emotional response to a violin chord stimulus comprised of continuous increases (up-ramp) or decreases (down-ramp) of intensity. A factorial experiment manipulated direction of intensity change (60–90 dB SPL up-ramp, 90–60 dB SPL down-ramp) and duration (1.8 s, 3.6 s) within-subjects (N = 45). Dependent variables were ratings of emotional arousal, valence, and loudness change, and a fine-grained analysis of event-related skin conductance response (SCR). As hypothesized, relative to down-ramps, musical up-ramps elicited significantly higher ratings of emotional arousal and loudness change, with marginally longer SCR rise times. However, SCR magnitude was greater in response to musical down-ramps. The implications of acoustic intensity change for music-induced emotion and auditory warning perception are discussed.

Skin Conductance Response to the Pain of Others Predicts Later Costly Helping

People show autonomic responses when they empathize with the suffering of another person. However, little is known about how these autonomic changes are related to prosocial behavior. We measured skin conductance responses (SCRs) and affect ratings in participants while either receiving painful stimulation themselves, or observing pain being inflicted on another person. In a later session, they could prevent the infliction of pain in the other by choosing to endure pain themselves. Our results show that the strength of empathy-related vicarious skin conductance responses predicts later costly helping. Moreover, the higher the match between SCR magnitudes during the observation of pain in others and SCR magnitude during self pain, the more likely a person is to engage in costly helping. We conclude that prosocial motivation is fostered by the strength of the vicarious autonomic response as well as its match with first-hand autonomic experience.

Sex-specific association between psychopathic traits and electrodermal reactivity in children.

This study investigated the relationship of skin conductance response (SCR) to a child psychopathy measure. Blunted electrodermal activity is a theoretically important characteristic of psychopathy, but it has not been fully explored in preadolescents or females. The authors tested the hypothesis that reduced SCR magnitude is associated with psychopathic-like traits in boys and girls. Participants were drawn from an ethnically diverse community sample of 9- to 10-year-old twins. Given the fact that members of each twin pair were rated by the same individual (i.e., their caregiver) on the Child Psychopathy Scale, the authors examined individual differences at the within-family level. Skin conductance data were collected during a passive auditory task consisting of 75-dB tones as well as miscellaneous sounds (e.g., baby cries, bird noises, and speech-like stimuli). Reduced SCR magnitude (hyporeactivity) was characteristic only of boys with higher psychopathy scores. More specifically, electrodermal hyporeactivity was linked to the interpersonal facet of psychopathy, suggesting that it is a biological marker of a manipulative and deceitful orientation in males. No association was found between SCRs and psychopathic traits in girls, indicating the importance of sex specific etiologies of psychopathy in childhood.

Early brain-body impact of emotional arousal

Current research in affective neuroscience suggests that the emotional content of visual stimuli activates brain–body responses that could be critical to general health and physical disease. The aim of this study was to develop an integrated neurophysiological approach linking central and peripheral markers of nervous activity during the presentation of natural scenes in order to determine the temporal stages of brain processing related to the bodily impact of emotions. More specifically, whole head magnetoencephalogram (MEG) data and skin conductance response (SCR), a reliable autonomic marker of central activation, were recorded in healthy volunteers during the presentation of emotional (unpleasant and pleasant) and neutral pictures selected from the International Affective Picture System (IAPS). Analyses of event-related magnetic fields (ERFs) revealed greater activity at 180 ms in an occipitotemporal component for emotional pictures than for neutral counterparts. More importantly, these early effects of emotional arousal on cerebral activity were significantly correlated with later increases in SCR magnitude. For the first time, a neuromagnetic cortical component linked to a well-documented marker of bodily arousal expression of emotion, namely, the SCR, was identified and located. This finding sheds light on the time course of the brain–body interaction with emotional arousal and provides new insights into the neural bases of complex and reciprocal mind–body links.

Age differences in perception and awareness of emotion

We investigated the effects of age and gender on emotional perception and physiology using electrodermal skin conductance response (SCR) and examined whether SCR is related to subjective perceptions of emotional pictures. Older adults found pictures to be more positive and arousing than younger participants. Older women rated pictures more extremely at both ends of the valence continuum: they rated positive pictures more positively and negative pictures more negatively. Elders were less likely to show measurable SCRs. However, magnitude of SCRs when a response occurred did not differ between young and old. Subjective ratings of emotion correlated with physiological responses in younger participants, but they were unrelated in older participants. Thus, in older adults the perception of emotional events was disconnected from the physiological state induced by emotion.

Skin conductance responses to visual sexual stimuli

Previous research showed that the asymmetrical direction of bilateral skin conductance responses (SCRs) remains constant regardless of task (with larger left SCRs in men and larger right SCRs in women). However, SCRs are controlled ipsilaterally by structures also associated with sexual arousal, hence it could be expected that larger right SCRs are specifically elicited by sexual stimuli. In order to test the two competing hypotheses, left and right SCR magnitude to three stimulus categories (sexually explicit, sexually non-explicit and neutral) were compared in 54 subjects (27 females). The direction of the asymmetry remained constant across stimulus types, however, unexpected sex differences occurred, as males had larger right SCRs and there was no lateralization in females. Interestingly, this interaction disappeared after controlling for indicators of subjective sexual arousal, suggesting that a specific (not previously hypothesized) processing of sexual information could take place.

Psychophysiological anticipation of positive outcomes promotes advantageous decision-making in normal older persons

Previous studies have demonstrated that aging has an adverse effect on laboratory decision-making in some older adults, and such findings have important implications for real-world reasoning and judgment. Emotion, and its accompanying somatic responses, is thought to contribute significantly to decision-making. In the present study, we had two objectives: 1) to investigate decision-making in a new sample of elderly participants, using the Iowa Gambling Task (IGT); and 2) to investigate psychophysiological correlates of decision-making, focusing on anticipatory skin conductance responses (SCRs) that participants produce immediately prior to their behavioral response. We hypothesized that the previous behavioral findings would be replicated, and further, that the older adult participants with IGT impairments would show a lack of discriminatory anticipatory SCRs during the IGT. The results supported both predictions. First, a subgroup of the new elderly sample demonstrated impaired decision-making on the IGT, replicating our previous findings. Second, the participants with impaired IGT performance failed to demonstrate discriminatory anticipatory SCRs for advantageous versus disadvantageous choices, whereas participants with normal IGT performance did demonstrate such discrimination; in the latter case, however, SCR magnitude was higher for advantageous decisions (unlike the pattern in young normal adults). Our data lead to the suggestion that strong decision-making abilities among older adults may be a function of positive somatic markers, whereas poor decision-making abilities may arise from an abnormal somatic response generated in anticipation of a future event.

Skin conductance responses are elicited by the airway sensory effects of puffs from cigarettes

The airway sensations stimulated by smoking are an important source of hedonic impact (pleasure) for dependent smokers. The learning process by which these sensations become pleasurable is not well understood. The classical conditioning model predicts that airway sensory stimulation will elicit sympathetic arousal that is positively correlated with the hedonic impact that is elicited by airway sensory stimulation. To test this prediction, we measured skin conductance responses (SCRs) and subjective hedonic impact elicited by a series of individual puffs from nicotinized, denicotinized and unlit cigarettes. Nicotinized puffs elicited more subjective hedonic impact than denicotinized and unlit puffs partly as a result of the fact that they provided a greater level of airway sensory stimulation. We found that SCRs were not larger for nicotinized puffs than for denicotinized puffs, but that they were larger for both nicotinized and denicotinized puffs than for unlit puffs. We also found that the average SCR of a subject to denicotinized puffs was positively correlated with the average hedonic impact that a subject obtained from denicotinized puffs. Together, this suggests that SCR magnitude does not reflect within-subject variations in hedonic impact that are due to variations in the level of airway sensory stimulation, but that it does reflect individual differences in the amount of hedonic impact that is derived from a given level of airway sensory stimulation. The results of a post hoc correlation analysis suggest that these individual differences may have been due to variations in the prevailing urge to smoke. The implications of these findings for the classical conditioning model, as well as for other learning models, are discussed.

Decision-making in amnesia: Do advantageous decisions require conscious knowledge of previous behavioural choices?

Previous work has reported that in the Iowa gambling task (IGT) advantageous decisions may be taken before the advantageous strategy is known [Bechara, A., Damasio, H., Tranel, D., & Damasio, A. R. (1997). Deciding advantageously before knowing the advantageous strategy. Science, 275, 1293–1295]. In order to test whether explicit memory is essential for the acquisition of a behavioural preference for advantageous choices, we measured behavioural performance and skin conductance responses (SCRs) in five patients with dense amnesia following damage to the basal forebrain and orbitofrontal cortex, six amnesic patients with damage to the medial temporal lobe or the diencephalon, and eight control subjects performing the IGT. Across 100 trials healthy participants acquired a preference for advantageous choices and generated large SCRs to high levels of punishment. In addition, their anticipatory SCRs to disadvantageous choices were larger than to advantageous choices. However, this dissociation occurred much later than the behavioural preference for advantageous alternatives. In contrast, though exhibiting discriminatory autonomic SCRs to different levels of punishment, 9 of 11 amnesic patients performed at chance and did not show differential anticipatory SCRs to advantageous and disadvantageous choices. Further, the magnitude of anticipatory SCRs did not correlate with behavioural performance. These results suggest that the acquisition of a behavioural preference – be it for advantageous or disadvantageous choices – depends on the memory of previous reinforcements encountered in the task, a capacity requiring intact explicit memory.

Processing of the Arousal of Subliminal and Supraliminal Emotional Stimuli by the Human Amygdala

The amygdala is known to play an important role in conscious and unconscious processing of emotional and highly arousing stimuli. Neuroanatomical evidence suggests that the amygdala participates in the control of autonomic responses, such as skin conductance responses (SCRs), elicited by emotionally salient stimuli, but little is known regarding its functional role in such control. We investigated this issue by showing emotional visual stimuli of varying arousal to patients with left (n = 12), right (n = 8), and bilateral (n = 3) amygdala damage and compared their results with those from 38 normal controls. Stimuli were presented both subliminally (using backward masking) and supraliminally under lateralized presentation to one visual hemifield. We collected SCRs as a physiological index of emotional responses. Subjects subsequently rated each stimulus on valence and arousal under free viewing conditions. There were two key findings: (1) impaired overall SCR after right amygdala damage; and (2) impaired correlation of SCR with the rated arousal of the stimuli after left amygdala damage. The second finding was strengthened further by finding a positive correlation between the evoked SCR magnitude and postsurgery amygdala volume, indicating impaired autonomic responses with larger tissue damage. Bilateral amygdala damage resulted in severe impairments on both of the above measures. Our results provide support for the hypothesis that the left and right amygdalae subserve different functions in emotion processing: the left may decode the arousal signaled by the specific stimulus, whereas the right may provide a global level of autonomic activation triggered automatically by any arousing stimulus.