Publication recommendations for electrodermal measurements

Neural correlates of and processes underlying generalized and differential return of fear

Relapse represents a major limitation to long-term remission of psychopathology (anxiety, addiction). Relapse of anxiety can be modeled in the laboratory as return of fear (ROF) following un-signaled re-presentation of the aversive event (reinstatement, RI) after extinction. In humans, response enhancement to both the CS+ and CS- (generalized RI) or specifically to the CS+ (differential RI) has been described following RI. The (psychological) mechanisms and boundary conditions underlying these different RI qualities were investigated in 76 healthy participants using autonomic measures and functional magnetic resonance imaging. Our results suggest that both processes reflect distinct albeit intertwined (psychological) processes which are reflected in different neural activation patterns. Differential RI was linked to CS+ related hippocampal activation and CS- related disinhibition of the ventromedial prefrontal cortex (vmPFC). The latter likely contributes to robust generalized RI which was mirrored in thalamic and visual areas (as well as the bed nucleus of the striatum and inusula) possibly indicating generally facilitated salience processing. In addition, we also present data on experimental boundary conditions of RI (trial sequence effects, time stability). Taken together, this first comprehensive analysis of RI-induced ROF aids not only experimental research on ROF but also understanding of factors promoting clinical relapse and the role of the vmPFC.

Sex differences in conditioned stimulus discrimination during context-dependent fear learning and its retrieval in humans: the role of biological sex, contraceptives and menstrual cycle phases

BACKGROUND

Anxiety disorders are more prevalent in women than in men. Despite this sexual dimorphism, most experimental studies are conducted in male participants and studies focusing on sex differences are sparse. In addition, the role of hormonal contraceptives and menstrual cycle phase in fear conditioning and extinction processes remain largely unknown.

METHODS

We investigated sex differences in context-dependent fear acquisition and extinction (day 1) and their retrieval/expression (day 2). Skin conductance responses (SCRs), fear and unconditioned stimulus expectancy ratings were obtained.

RESULTS

We included 377 individuals (261 women) in our study. Robust sex differences were observed in all dependent measures. Women generally displayed higher subjective ratings but smaller SCRs than men and showed reduced excitatory/inhibitory conditioned stimulus (CS+/CS-) discrimination in all dependent measures. Furthermore, women using hormonal contraceptives showed reduced SCR CS discrimination on day 2 than men and free-cycling women, while menstrual cycle phase had no effect.

LIMITATIONS

Possible limitations include the simultaneous testing of up to 4 participants in cubicles, which might have introduced a social component, and not assessing postexperimental contingency awareness.

CONCLUSION

The response pattern in women shows striking similarity to previously reported sex differences in patients with anxiety. Our results suggest that pronounced deficits in associative discrimination learning and subjective expression of safety information (CS- responses) might underlie higher prevalence and higher symptom rates seen in women with anxiety disorders. The data call for consideration of biological sex and hormonal contraceptive use in future studies and may suggest that targeting inhibitory learning during therapy might aid precision medicine.

Neural signatures of experimentally induced flow experiences identified in a typical fMRI block design with BOLD imaging

Previously, experimentally induced flow experiences have been demonstrated with perfusion imaging during activation blocks of 3 min length to accommodate with the putatively slowly evolving "mood" characteristics of flow. Here, we used functional magnetic resonance imaging (fMRI) in a sample of 23 healthy, male participants to investigate flow in the context of a typical fMRI block design with block lengths as short as 30 s. To induce flow, demands of arithmetic tasks were automatically and continuously adjusted to the individual skill level. Compared against conditions of boredom and overload, experience of flow was evident from individuals' reported subjective experiences and changes in electrodermal activity. Neural activation was relatively increased during flow, particularly in the anterior insula, inferior frontal gyri, basal ganglia and midbrain. Relative activation decreases during flow were observed in medial prefrontal and posterior cingulate cortex, and in the medial temporal lobe including the amygdala. Present findings suggest that even in the context of comparably short activation blocks flow can be reliably experienced and is associated with changes in neural activation of brain regions previously described. Possible mechanisms of interacting brain regions are outlined, awaiting further investigation which should now be possible given the greater temporal resolution compared with previous perfusion imaging.

Alterations in electrodermal activity and cardiac parasympathetic tone during hypnosis

Exploring autonomic nervous system (ANS) changes during hypnosis is critical for understanding the nature and extent of the hypnotic phenomenon and for identifying the mechanisms underlying the effects of hypnosis in different medical conditions. To assess ANS changes during hypnosis, electrodermal activity and pulse rate variability (PRV) were measured in 121 young adults. Participants either received hypnotic induction (hypnosis condition) or listened to music (control condition), and both groups were exposed to test suggestions. Blocks of silence and experimental sound stimuli were presented at baseline, after induction, and after de-induction. Skin conductance level (SCL) and high frequency (HF) power of PRV measured at each phase were compared between groups. Hypnosis decreased SCL compared to the control condition; however, there were no group differences in HF power. Furthermore, hypnotic suggestibility did not moderate ANS changes in the hypnosis group. These findings indicate that hypnosis reduces tonic sympathetic nervous system activity, which might explain why hypnosis is effective in the treatment of disorders with strong sympathetic nervous system involvement, such as rheumatoid arthritis, hot flashes, hypertension, and chronic pain. Further studies with different control conditions are required to examine the specificity of the sympathetic effects of hypnosis.

Determination of the maximum rate of eccrine sweat glands’ ion reabsorption using the galvanic skin conductance to local sweat rate relationship

PURPOSE

The purpose of the present study was to develop and describe a simple method to evaluate the rate of ion reabsorption of eccrine sweat glands in human using the measurement of galvanic skin conductance (GSC) and local sweating rate (SR). This purpose was investigated by comparing the SR threshold for increasing GSC with following two criteria of sweat ion reabsorption in earlier studies such as (1) the SR threshold for increasing sweat ion was at approximately 0.2–0.5 mg/cm2/min and (2) exercise heat acclimation improved the sweat ion reabsorption ability and would increase the criteria 1.

METHODS

Seven healthy non-heat-acclimated male subjects received passive heat treatment both before and after 7 days of cycling in hot conditions (50% maximum oxygen uptake, 60 min/day, ambient temperature 32 °C, and 50% relative humidity).

RESULTS

Subjects became partially heat-acclimated, as evidenced by the decreased end-exercise heart rate (p < 0.01), rate of perceived exhaustion (p < 0.01), and oesophageal temperature (p = 0.07), without alterations in whole body sweat loss, from the first to the last day of training. As hypothesized, we confirmed that the SR threshold for increasing GSC was near the predicted SR during passive heating before exercise heat acclimation, and increased significantly after training (0.19 ± 0.09–0.32 ± 0.10 mg/cm2/min, p < 0.05).

CONCLUSIONS

The reproducibility of sweat ion reabsorption by the eccrine glands in the present study suggests that the relationship between GSC and SR can serve as a new index for assessing the maximum rate of sweat ion reabsorption of eccrine sweat glands in humans.

Temperature effects on polygraph detection of concealed information

Thermoregulatory influences on electrodermal and cardiovascular activity may interfere with the detection of concealed information using a polygraph. This possibility was assessed by means of a mock terrorism scenario. Seventy-two participants were assigned to either a guilty or an innocent role. They were given a polygraph test at one of three ambient temperatures: 10°C, 22°C, or 34°C. Among guilty participants, electrodermal and cardiovascular measures were least effective at 10°C. Electrodermal results were optimal at 22°C, whereas cardiovascular results were optimal at 34°C. Among innocent participants, the effectiveness of these same measures was not affected by ambient temperature. Temperature had no significant impact on respiration results within the guilty or the innocent groups. Taken together, these findings have implications for those who use polygraphs in uncontrolled testing environments.

Electrodermal activity processing: a convex optimization approach

This paper reports on a novel model based on convex optimization methods for the analysis of the skin conductance (SC) as response of the electrodermal activity (EDA) to affective stimuli. Starting from previous assessed methodological approaches, this new model proposes a decomposition of SC into tonic and phasic components through the solution of a convex optimization problem. Previous knowledge about the physiology of the EDA is accounted for by means of an appropriate choice of constraints and regularizers. In order to test the effectiveness of the new approach, an experimental session in which 9 healthy subjects were stimulated using affective pictures gathered from the IAPS database was designed and carried out. The experimental session included series of negative-valence high-arousal images and series of neutral images, with an inter-stimulus interval of about 2 seconds for both neutral and high arousal pictures. Next, a statistical analysis was performed on a set of features extracted from the phasic driver and the tonic signal estimated by the model. Results showed that the phasic driver extracted from the model was able to strongly distinguish arousal sessions from neutral ones. Conversely, no significant difference was found for the tonic components. This experimental findings are consistent with the literature and confirm that the phasic component is strictly related to changes in the sympathetic activity of the autonomic nervous system. Although preliminary, these results are very encouraging and future work will progress to further validate the model through specific and controlled experiments.

Parental Anxiety Prospectively Predicts Fearful Children's Physiological Recovery from Stress

Parental anxiety confers risk for the development of an anxiety disorder in children, and this risk may be transmitted through children's stress reactivity. Further, some children may be more vulnerable to reactivity in the presence of parent factors such as anxiety. In this study, we examined whether parents' anxiety symptoms prospectively predict school-aged children's physiological reactivity following stress, assessed through their electrodermal activity (galvanic skin response) during recovery from a performance challenge task, and whether this varies as a function of children's temperamental fearfulness. Parents and their children (N = 68) reported on their anxiety symptoms at Time 1 of data collection, and parents characterized the extent to which their children had fearful temperaments. At Time 2 children completed the performance challenge and two recovery tasks. Greater parental anxiety symptom severity at Time 1 predicted children's higher electrodermal response during both recovery tasks following the failure task. Further, these effects are specific to children with medium and high fearful temperament, whereas for children low in fearfulness, the association between parent anxiety and child reactivity is not significant. Findings provide additional evidence for the diathesis-stress hypothesis and are discussed in terms of their contribution to the literature on developmental psychopathology.

Increased affective reactivity to neutral stimuli and decreased maintenance of affective responses in bipolar disorder

BACKGROUND

Affective dysregulation is a core feature of bipolar disorder (BD) and a significant predictor of clinical and functional outcome. Affective dysregulation can arise from abnormalities in multiple processes. This study addresses the knowledge gap regarding the precise nature of the processes that may be dysregulated in BD and their relationship to the clinical expression of the disorder.

METHODS

Patients with BD (n=45) who were either in remission or in a depressive or manic state and healthy individuals (n=101) were compared in terms of the intensity, duration and physiological response (measured using inter-beat intervals and skin conductance) to affective and neutral pictures during passive viewing and during experiential suppression.

RESULTS

Compared to healthy individuals, patients with BD evidenced increased affective reactivity to neutral pictures and reduced maintenance of subjective affective responses to all pictures. This pattern was present irrespective of clinical state but was more pronounced in symptomatic patients, regardless of polarity. Patients, regardless of symptomatic status, were comparable to healthy individuals in terms of physiological arousal and voluntary control of affective responses.

CONCLUSION

Our study demonstrates that increased affective reactivity to neutral stimuli and decreased maintenance of affective responses are key dimensions of affective dysregulation in BD.

When Threat Is Near, Get Out of Here

When detecting a threat, humans and other animals engage in defensive behaviors and supporting physiological adjustments that vary with threat imminence and potential response options. In the present study, we shed light on the dynamics of defensive behaviors and associated physiological adjustments in humans using multiple psychophysiological and brain measures. When participants were exposed to a dynamically approaching, uncontrollable threat, attentive freezing was augmented, as indicated by an increase in skin conductance, fear bradycardia, and potentiation of the startle reflex. In contrast, when participants had the opportunity to actively avoid the approaching threat, attention switched to response preparation, as indicated by an inhibition of the startle magnitude and by a sharp drop of the probe-elicited P3 component of the evoked brain potentials. These new findings on the dynamics of defensive behaviors form an important intersection between animal and human research and have important implications for understanding fear and anxiety-related disorders.

Generalization of Contextual Fear in Humans

Enhanced fear responses to cues, which were not associated with the threat but share perceptual characteristics with the threat signal, indicate generalization of conditioned fear. Here, we investigated for the first time generalization processes in contextual fear conditioning. Thirty-two participants were guided through two virtual offices (acquisition phases). Mildly painful electric shocks (unconditioned stimulus, US) were unpredictably delivered in one office (anxiety context, CTX+), but never in the other office (safety context, CTX-). During the generalization test, participants were guided through CTX+, CTX-, and the generalization context (G-CTX), which contained features of both the CTX+ and the CTX-, but no US was delivered. We found successful contextual fear conditioning (i.e., the CTX+ compared to the CTX- elicited potentiated startle responses and was rated with more negative valence, higher arousal and higher anxiety). Importantly, implicit and explicit responses dissociated in the generalization test. Thus, participants rated the G-CTX as more arousing and anxiogenic than the CTX- indicating anxiety generalization, but they showed enhanced startle responses to the CTX+ only, while the G-CTX and the CTX- did not differ. In summary, healthy participants on an explicit level responded to the generalization context like to the anxiety context, but on an implicit level responded to the generalization context like to the safety context. Possibly, this dissociation suggests distinct and specific generalization processes underlying contextual fear.

The framing effect and skin conductance responses

Individuals often rely on simple heuristics when they face complex choice situations under uncertainty. Traditionally, it has been proposed that cognitive processes are the main driver to evaluate different choice options and to finally reach a decision. Growing evidence, however, highlights a strong interrelation between judgment and decision-making (JDM) on the one hand, and emotional processes on the other hand. This also seems to apply to judgmental heuristics, i.e., decision processes that are typically considered to be fast and intuitive. In this study, participants are exposed to different probabilities of receiving an unpleasant electric shock. Information about electric shock probabilities is either positively or negatively framed. Integrated skin conductance responses (ISCRs) while waiting for electric shock realization are used as an indicator for participants' emotional arousal. This measure is compared to objective probabilities. I find evidence for a relation between emotional body reactions measured by ISCRs and the framing effect. Under negative frames, participants show significantly higher ISCRs while waiting for an electric shock to be delivered than under positive frames. This result might contribute to a better understanding of the psychological processes underlying JDM. Further studies are necessary to reveal the causality underlying this finding, i.e., whether emotional processes influence JDM or vice versa.

Effects of hearing loss on heart rate variability and skin conductance measured during sentence recognition in noise

OBJECTIVE

The purpose of the study was to determine the effects of hearing loss and noise on (1) two autonomic nervous system measures associated with stress (skin conductance and heart rate variability) and on (2) subjective ratings of workload/stress. The authors hypothesized that hearing loss would increase psychophysiological and subjective reactivity to noise during speech recognition tasks. Both psychophysiological and subjective indicators of workload/stress were expected to increase with a reduction in signal-to-noise ratio.

DESIGN

Sentence recognition in the presence of babble noise was assessed in 15 adults with clinically normal hearing and 18 adults with sensorineural hearing loss. Mean sentence recognition was equalized for the two groups using an adaptive procedure to estimate 80% recognition of words in sentences. Sentences were then presented in quiet and at four fixed signal-to-noise ratios: -6, -3, 0, and +3 dB relative to the individually determined signal-to-noise thresholds. Electrocardiography and skin conductance recordings were obtained during each listening condition. The high-frequency spectral component of heart rate variability was extracted from the electrocardiographic recordings as a measure of parasympathetic nervous system activity. Subjective ratings of effort, mental demand, stress, and perceived performance were obtained after each listening condition using the National Aeronautics and Space Administration Task Load Index.

RESULTS

Recognition scores referenced to the adaptive threshold were similar for the two groups. Participants with hearing loss showed a decrease in high-frequency heart rate variability at lower signal-to-noise ratios, whereas those with normal hearing did not. Skin conductance levels were not sensitive to changes in signal-to-noise ratio. However, overall skin conductance reactivity to noise (relative to quiet) was higher for those with hearing loss than for those with normal hearing. In contrast to the psychophysiological findings, there were no significant differences between subjective ratings for the two groups.

CONCLUSIONS

Listeners with hearing loss show greater autonomic nervous system reactivity to babble noise during speech recognition than do listeners with normal hearing, when recognition performance is equal. The findings are consistent with the conclusion that listeners with hearing loss experience increased effort and/or stress during speech recognition in noise.

Learning to (dis)like: The effect of evaluative conditioning with tastes and faces on odor valence assessed by implicit and explicit measurements

Evaluative conditioning may be an important mechanism for learning food preferences and aversions; however, in both real life and experimental settings it has not been consistently successful. The current study aimed to gain more insight into which underlying factors may contribute to a successful outcome of olfactory evaluative conditioning. Two groups of 18 participants came in on three consecutive days, and were repeatedly exposed to four novel, neutral odors (CS) coupled to varying disliked, neutral, liked, or no stimuli (taste and/or pictures, US), following a 50% reinforcement schedule, leading to 40 odor presentations per session. Liking ratings, as well as changes in the autonomic nervous system were assessed before, during and after conditioning. We were able to induce negative, but not positive, affective changes by pairing neutral odors with tastes and pictures differing in valence. Negative as well as multimodal stimuli appear to be more potent US, since they may be considered more salient. Lastly, results of the current study imply that heart rate is responsive to changes in valence of olfactory stimuli, and perhaps even more sensitive than explicit ratings of liking.

Electrodermal activity analysis during affective haptic elicitation

This paper investigates how the autonomic nervous system dynamics, quantified through the analysis of the electrodermal activity (EDA), is modulated according to affective haptic stimuli. Specifically, a haptic display able to convey caress-like stimuli is presented to 32 healthy subjects (16 female). Each stimulus is changed according to six combinations of three velocities and two forces levels of two motors stretching a strip of fabric. Subjects were also asked to score each stimulus in terms of arousal (high/low activation) and valence (pleasant/unpleasant), in agreement with the circumplex model of affect. EDA was processed using a deconvolutive method, separating tonic and phasic components. A statistical analysis was performed in order to identify significant differences in EDA features among force and velocity levels, as well as in their valence and arousal scores. Results show that the simulated caress induced by the haptic display significantly affects the EDA. In detail, the phasic component seems to be inversely related to the valence score. This finding is new and promising, since it can be used, e.g., as an additional cue for haptics design.

Neural mechanisms of placebo anxiolysis

The beneficial effects of placebo treatments on fear and anxiety (placebo anxiolysis) are well known from clinical practice, and there is strong evidence indicating a contribution of treatment expectations to the efficacy of anxiolytic drugs. Although clinically highly relevant, the neural mechanisms underlying placebo anxiolysis are poorly understood. In two studies in humans, we tested whether the administration of an inactive treatment along with verbal suggestions of anxiolysis can attenuate experimentally induced states of phasic fear and/or sustained anxiety. Phasic fear is the response to a well defined threat and includes attentional focusing on the source of threat and concomitant phasic increases of autonomic arousal, whereas in sustained states of anxiety potential and unclear danger requires vigilant scanning of the environment and elevated tonic arousal levels. Our placebo manipulation consistently reduced vigilance measured in terms of undifferentiated reactivity to salient cues (indexed by subjective ratings, skin conductance responses and EEG event-related potentials) and tonic arousal [indexed by cue-unrelated skin conductance levels and enhanced EEG alpha (8-12 Hz) activity], indicating a downregulation of sustained anxiety rather than phasic fear. We also observed a placebo-dependent sustained increase of frontal midline EEG theta (4-7 Hz) power and frontoposterior theta coupling, suggesting the recruitment of frontally based cognitive control functions. Our results thus support the crucial role of treatment expectations in placebo anxiolysis and provide insight into the underlying neural mechanisms.

Temporally Unpredictable Sounds Exert a Context-Dependent Influence on Evaluation of Unrelated Images

Temporally unpredictable stimuli influence murine and human behaviour, as previously demonstrated for sequences of simple sounds with regular or irregular onset. It is unknown whether this influence is mediated by an evaluation of the unpredictable sound sequences themselves, or by an interaction with task context. Here, we find that humans evaluate unrelated neutral pictures as more negative when these are presented together with a temporally unpredictable sound sequence, compared to a predictable sequence. The same is observed for evaluation of neutral, angry and fearful face photographs. Control experiments suggest this effect is specific to interspersed presentation of negative and neutral visual stimuli. Unpredictable sounds presented on their own were evaluated as more activating, but not more aversive, and were preferred over predictable sounds. When presented alone, these sound sequences also did not elicit tonic autonomic arousal or negative mood change. We discuss how these findings might account for previous data on the effects of unpredictable sounds, in humans and rodents.

Continuous electrodermal activity as a potential novel neurophysiological biomarker of prognosis after cardiac arrest--A pilot study

AIMS

Neurological outcome prognosis remains challenging in patients undergoing therapeutic hypothermia (TH) after cardiac resuscitation. Technological advances allow for a novel wrist-worn device to continuously record electrodermal activity (EDA), a measure of pure sympathetic activity.

METHODS

A prospective cohort study was performed to determine the yield of continuous EDA in patients treated with TH for coma after cardiac arrest during hypothermia and normothermia. Association between EDA parameters (event-related and nonspecific electrodermal responses (ER-EDR, NS-EDR)) and outcome measures (cerebral performance category [CPC]) (Full Outline in UnResponsivenss (FOUR) score) were assessed.

RESULTS

Eighteen patients were enrolled. Total number of EDR (66.4 vs 12.0/24h, p = 0.02), ER-EDR (39.5 vs 11.2/24h, p = 0.009), median amplitude change of all EDR (0.08 vs 0.03 μSI, p = 0.03) and ER-EDR (0.14 vs 0.05 μSI, p = 0.025) were higher in patients with favorable (CPC 1-2) versus poor outcome (CPC 3-5) during hypothermia. Greater differences in EDA parameters were observed during hypothermia than normothermia. The FOUR score was correlated to the number of all EDR and median amplitudes.

CONCLUSIONS

Continuous EDA potentially opens a new avenue for autonomic function monitoring in neurocritically ill patients. It is feasible in the ICU setting, even during hypothermic states. As a measure of a complete neurophysiological circuit, it may be a novel neurophysiologic biomarker of outcome after cardiac resuscitation.

Neural circuitry underlying effects of context on human pain-related fear extinction in a renewal paradigm

OBJECTIVES

The role of context in pain-related extinction learning remains poorly understood. We analyzed the neural mechanisms underlying context-dependent extinction and renewal in a clinically relevant model of conditioned abdominal pain-related fear.

EXPERIMENTAL DESIGN

In this functional magnetic resonance imaging study, two groups of healthy volunteers underwent differential fear conditioning with painful rectal distensions as unconditioned stimuli (US) and visual conditioned stimuli (CS(+) ; CS(-) ). The extinction context was changed in an experimental group (context group), which was subsequently returned into the original learning context to test for renewal. No context changes occurred in the control group. Group differences in CS-induced differential neural activation were analyzed along with skin conductance responses (SCR), CS valence and CS-US contingency ratings.

PRINCIPAL OBSERVATIONS

During extinction, group differences in differential neural activation were observed in dorsolateral (dlPFC) and ventromedial (vmPFC) prefrontal cortex and amygdala, mainly driven by enhanced activation in response to the CS(-) in the control group. During renewal, observed group differences in activation of dlPFC and orbitofrontal cortex (OFC) resulted primarily from differential modulation of the CS(-) in the absence of group differences in response to CS(+) or SCR.

CONCLUSION

The extinction context affects the neural processing of nonpain predictive safety cues, supporting a role of safety learning in pain-related memory processes.

Deceptive Intentions: Can Cues to Deception Be Measured before a Lie Is Even Stated?

Can deceitful intentions be discriminated from truthful ones? Previous work consistently demonstrated that deceiving others is accompanied by nervousness/stress and cognitive load. Both are related to increased sympathetic nervous system (SNS) activity. We hypothesized that SNS activity already rises during intentions to lie and, consequently, cues to deception can be detected before stating an actual lie. In two experiments, controlling for prospective memory, we monitored SNS activity during lying, truth telling, and truth telling with the aim of lying at a later instance. Electrodermal activity (EDA) was used as an indicator of SNS. EDA was highest during lying, and compared to the truth condition, EDA was also raised during the intention to deceive. Moreover, the switch from truth telling toward lying in the intention condition evoked higher EDA than switching toward non-deception related tasks in the lie or truth condition. These results provide first empirical evidence that increased SNS activity related to deception can be monitored before a lie is stated. This implies that cues to deception are already present during the mere intention to lie.

Integrating electrodermal biofeedback into pharmacologic treatment of grand mal seizures

Electrodermal activity (EDA) and electrodermal biofeedback, when integrated with pharmacologic treatments, indicate promising methods for the treatment of grand mal seizures. They can be used to monitor patient arousal and help patients learn new strategies to better cope with stress and anxiety. Our proposed method can possibly reduce the number of crises for patients who are dependent on pharmacologic therapy and can improve their quality of life. This article describes the scientific background of electrodermal monitoring and electrodermal biofeedback for patients affected by grand mal seizures. In this study, we have reported a clinical case study. The patient was treated for 2 years with electrodermal biofeedback to augment pharmacologic treatments. The trial has been designed in accordance with “n = 1 case study research”. Our results have shown that our methods could achieve a significant reduction in grand mal seizures and sympathetic arousal when applied. The patient under consideration was also relaxed and exhibited greater competency to cope with stress. Additionally, the patient’s sense of mastery and self-efficacy was enhanced.

A matching pursuit algorithm for inferring tonic sympathetic arousal from spontaneous skin conductance fluctuations

Tonic sympathetic arousal is often inferred from spontaneous fluctuations in skin conductance, and this relies on assumptions about the shape of these fluctuations and how they are generated. We have previously furnished a psychophysiological model for this relation, and an efficient and reliable inversion method to estimate tonic arousal from given data in the framework of dynamic causal modeling (DCM). Here, we provide a fast alternative inversion method in the form of a matching pursuit (MP) algorithm. Analyzing simulated data, this algorithm approximates the true underlying arousal up to about 10 spontaneous fluctuations per minute of data. For empirical data, we assess predictive validity as the ability to differentiate two known psychological arousal states. Predictive validity is comparable between the methods for three datasets, and also comparable to visual peak scoring. Computation time of the MP algorithm is 2-3 orders of magnitude faster for the MP than the DCM algorithm. In summary, the new MP algorithm provides a fast and reliable alternative to DCM inversion for SF data, in particular when the expected number of fluctuations is lower than 10 per minute, as in typical experimental situations.

Replay of conditioned stimuli during late REM and stage N2 sleep influences affective tone rather than emotional memory strength

Emotional memories are reprocessed during sleep, and it is widely assumed that this reprocessing occurs mainly during rapid eye movement (REM) sleep. In support for this notion, vivid emotional dreams occur mainly during REM sleep, and several studies have reported emotional memory enhancement to be associated with REM sleep or REM sleep-related parameters. However, it is still unknown whether reactivation of emotional memories during REM sleep strengthens emotional memories. Here, we tested whether re-presentation of emotionally learned stimuli during REM sleep enhances emotional memory. In a split-night design, participants underwent Pavlovian conditioning after the first half of the night. Neutral sounds served as conditioned stimuli (CS) and were either paired with a negative odor (CS+) or an odorless vehicle (CS-). During sound replay in subsequent late REM or N2 sleep, half of the CS+ and half of the CS- were presented again. In contrast to our hypothesis, replay during sleep did not affect emotional memory as measured by the differentiation between CS+ and CS- in expectancy, arousal and valence ratings. However, replay unspecifically decreased subjective arousal ratings of both emotional and neutral sounds and increased positive valence ratings also for both CS+ and CS- sounds, respectively. These effects were slightly more pronounced for replay during REM sleep. Our results suggest that re-exposure to previously conditioned stimuli during late sleep does not affect emotional memory strength, but rather influences the affective tone of both emotional and neutral memories.

Animals may act as social buffers: Skin conductance arousal in children with autism spectrum disorder in a social context

Children with autism spectrum disorder (ASD) experience high rates of social stress and anxious arousal. Preliminary evidence suggests that companion animals can act as buffers against the adverse effects of social stress in adults. We measured continuous physiological arousal in children with ASD and typically developing (TD) children in a social context during four conditions: (a) a baseline of reading silently, (b) a scripted classroom activity involving reading aloud, (c) free play with peers and toys, and (d) free play with peers and animals (guinea pigs). Our results confirmed heightened arousal among children with ASD compared to TD children in all conditions, except when the animals were present. Children with ASD showed a 43% decrease in skin conductance responses during free play with peers in the presence of animals, compared to toys. Thus, animals may act as social buffers for children with ASD, conferring unique anxiolytic effects.

Sensitivity towards fear of electric shock in passive threat situations

Human judgment and decision-making (JDM) requires an assessment of different choice options. While traditional theories of choice argue that cognitive processes are the main driver to reach a decision, growing evidence highlights the importance of emotion in decision-making. Following these findings, it appears relevant to understand how individuals asses the attractiveness or riskiness of a situation in terms of emotional processes. The following study aims at a better understanding of the psychophysiological mechanisms underlying threat sensitivity by measuring skin conductance responses (SCRs) in passive threat situations. While previous studies demonstrate the role of magnitude on emotional body reactions preceding an outcome, this study focuses on probability. In order to analyze emotional body reactions preceding negative events with varying probability of occurrence, we have our participants play a two-stage card game. The first stage of the card game reveals the probability of receiving an unpleasant electric shock. The second stage applies the electric shock with the previously announced probability. For the analysis, we focus on the time interval between the first and second stage. We observe a linear relation between SCRs in anticipation of receiving an electric shock and shock probability. This finding indicates that SCRs are able to code the likelihood of negative events. We outline how this coding function of SCRs during the anticipation of negative events might add to an understanding of human JDM.

Contextual fear conditioning in humans using feature-identical contexts

Contextual fear conditioning studies in animals and humans found an involvement of the hippocampus and amygdala during fear learning. To exclude a focus on elements of the context we employed a paradigm, which uses two feature-identical contexts that only differ in the arrangement of the features and requires configural processing. We employed functional magnetic resonance imaging to determine the role of the hippocampus and neocortical areas during the acquisition of contextual fear in humans. For contextual fear acquisition, we paired one context (CS+) with an aversive electrical stimulus, whereas the other (CS-) was never followed by aversive stimulation. Blood oxygen level dependent activation to the CS+ was present in the insula, inferior frontal gyrus, inferior parietal lobule, superior medial gyrus and caudate nucleus. Furthermore, the amygdala and hippocampus were involved in a time-dependent manner. Psychophysiological interaction analyses revealed functional connectivity of a more posterior hippocampal seed region with the anterior hippocampus, posterior cingulate cortex and superior parietal lobule. The anterior hippocampus was functionally coupled with the amygdala and postcentral gyrus. This study complements previous findings in contextual fear conditioning in humans and provides a paradigm which might be useful for studying patients with hippocampal impairment.

Comment: The Methodological and Conceptual Utility of Differentiating Emotional Arousal

The concept of psychophysiological arousal as a component of emotional behavior has a long history, but has not attracted the research attention paid to valence in the burgeoning field of affective neuroscience. The potency of emotional stimuli is often poorly balanced in studies designed to assess appetitive and aversive stimulus processing, and thus I applaud Picard and colleagues’ choice to highlight the arousal dimension of emotional behavior. Any attempt to understand the nature of human emotion must carefully balance the evocative impact of appetitive and aversive processes. By focusing on the contribution of arousal to emotional processing, Picard advances this goal. In this comment I suggest methodological and conceptual refinements that may help to strengthen the multiple arousal theory perspective.

Sparse representation of electrodermal activity with knowledge-driven dictionaries

Biometric sensors and portable devices are being increasingly embedded into our everyday life, creating the need for robust physiological models that efficiently represent, analyze, and interpret the acquired signals. We propose a knowledge-driven method to represent electrodermal activity (EDA), a psychophysiological signal linked to stress, affect, and cognitive processing. We build EDA-specific dictionaries that accurately model both the slow varying tonic part and the signal fluctuations, called skin conductance responses (SCR), and use greedy sparse representation techniques to decompose the signal into a small number of atoms from the dictionary. Quantitative evaluation of our method considers signal reconstruction, compression rate, and information retrieval measures, that capture the ability of the model to incorporate the main signal characteristics, such as SCR occurrences. Compared to previous studies fitting a predetermined structure to the signal, results indicate that our approach provides benefits across all aforementioned criteria. This paper demonstrates the ability of appropriate dictionaries along with sparse decomposition methods to reliably represent EDA signals and provides a foundation for automatic measurement of SCR characteristics and the extraction of meaningful EDA features.

Brain morphology correlates of interindividual differences in conditioned fear acquisition and extinction learning

The neural circuits underlying fear learning have been intensively investigated in pavlovian fear conditioning paradigms across species. These studies established a predominant role for the amygdala in fear acquisition, while the ventromedial prefrontal cortex (vmPFC) has been shown to be important in the extinction of conditioned fear. However, studies on morphological correlates of fear learning could not consistently confirm an association with these structures. The objective of the present study was to investigate if interindividual differences in morphology of the amygdala and the vmPFC are related to differences in fear acquisition and extinction learning in humans. We performed structural magnetic resonance imaging in 68 healthy participants who underwent a differential cued fear conditioning paradigm. Volumes of subcortical structures as well as cortical thickness were computed by the semi-automated segmentation software Freesurfer. Stronger acquisition of fear as indexed by skin conductance responses was associated with larger right amygdala volume, while the degree of extinction learning was positively correlated with cortical thickness of the right vmPFC. Both findings could be conceptually replicated in an independent sample of 53 subjects. The data complement our understanding of the role of human brain morphology in the mechanisms of the acquisition and extinction of conditioned fear.

Biofeedback-based self-alert training reduces alpha activity and stabilizes accuracy in the Sustained Attention to Response Task

OBJECTIVE

Deficits in sustaining attention are common in various organic brain diseases. A recent study proposed self-alert training (SAT) as a technique to improve sustained attention. In the SAT, individuals learn to gain volitional control over their own state of arousal by means of electrodermal biofeedback.

METHOD

In this study, we investigated the behavioral, electrodermal, and electroencephalogram correlates of the SAT with a blinded, randomized, and active-controlled pre-post study design. Sustained attention capacity was assessed with the Sustained Attention to Response Task (SART).

RESULTS

The SAT resulted in strong phasic increases in skin conductance response (SCR), but endogenous control of SCR without feedback was problematic. Electroencephalogram analysis revealed stronger alpha reduction during SART for the SAT than for the control group. Behaviorally, the SAT group performed more accurately and more slowly after intervention than the control group.

CONCLUSION

The study provides further evidence that SAT helps to maintain SART accuracy over prolonged periods of time. Whether this accuracy is more related to sustained attention or response inhibition is discussed.

'What is more familiar than I? Self, other and familiarity in schizophrenia

BACKGROUND

Familiarity disorders (FDs) critically impact social cognition in persons with schizophrenia. FDs can affect both relationships with people familiar to the patient and the patient's relationship with himself, in the case of a self-disorder. Skin conductance response (SCR) studies have shown that familiar and unknown faces elicit the same emotional response in persons with schizophrenia with FD. Moreover, in control subjects, one's own face and familiar faces have been shown to activate strongly overlapping neural networks, suggesting common processing. The aim of the present study was to determine whether the mechanisms involved in processing one's own and familiar faces are similarly impaired in persons with schizophrenia, suggesting a link between them.

METHOD

Twenty-eight persons with schizophrenia were compared with twenty control subjects. Three face conditions were used: specific familiar, self and unknown. The task was to indicate the gender of the faces presented randomly on a screen during SCR recording. Face recognition was evaluated afterwards.

RESULTS

Control subjects exhibited similar SCRs for the familiar and self-conditions, which were higher than the responses elicited by the unknown condition, whereas persons with schizophrenia exhibited no significant differences between the three conditions.

CONCLUSION

Persons with schizophrenia have a core defect of both self and familiarity that is emphasised by the lack of an increased SCR upon presentation with either self or familiar stimuli. Familiarity with specific familiar faces and one's own face may be driven by the same mechanism. This perturbation may predispose persons with schizophrenia to delusions and, in particular, to general familiarity disorder.

Does trans-spinal direct current stimulation alter phrenic motoneurons and respiratory neuromechanical outputs in humans? A double-blind, sham-controlled, randomized, crossover study

Although compelling evidence has demonstrated considerable neuroplasticity in the respiratory control system, few studies have explored the possibility of altering descending projections to phrenic motoneurons (PMNs) using noninvasive stimulation protocols. The present study was designed to investigate the immediate and long-lasting effects of a single session of transcutaneous spinal direct current stimulation (tsDCS), a promising technique for modulating spinal cord functions, on descending ventilatory commands in healthy humans. Using a double-blind, controlled, randomized, crossover approach, we examined the effects of anodal, cathodal, and sham tsDCS delivered to the C3-C5 level on (1) diaphragm motor-evoked potentials (DiMEPs) elicited by transcranial magnetic stimulation and (2) spontaneous ventilation, as measured by respiratory inductance plethysmography. Both anodal and cathodal tsDCS induced a progressive increase in DiMEP amplitude during stimulation that persisted for at least 15 min after current offset. Interestingly, cathodal, but not anodal, tsDCS induced a persistent increase in tidal volume. In addition, (1) short-interval intracortical inhibition, (2) nonlinear complexity of the tidal volume signal (related to medullary ventilatory command), (3) autonomic function, and (4) compound muscle action potentials evoked by cervical magnetic stimulation were unaffected by tsDCS. This suggests that tsDCS-induced aftereffects did not occur at brainstem or cortical levels and were likely not attributable to direct polarization of cranial nerves or ventral roots. Instead, we argue that tsDCS could induce sustained changes in PMN output. Increased tidal volume after cathodal tsDCS opens up the perspective of harnessing respiratory neuroplasticity as a therapeutic tool for the management of several respiratory disorders.

Reduced Responsiveness to Social Provocation in Autism Spectrum Disorder

Deficits in emotion processing and social interaction are prominent symptoms of autism spectrum disorder (ASD). ASD has also been associated with aggressive tendencies towards self and others. The prevalence of aggressive behavior in this disorder, its etiology and its impact on social life are still unclear. This study investigated behavioral and physiological effects of social provocation in patients with ASD and healthy controls. We used a modified Taylor Aggression Paradigm in 24 high-functioning patients with ASD and 24 healthy controls. Participants were instructed to play against a fictitious human opponent. Money withdrawals toward the participant represented provocation and money deduction by the participant denoted aggressive behavior. Throughout the measurement, electrodermal activity (EDA) was recorded. Healthy controls showed higher aggressive responses to high provocation compared to low provocation, which demonstrated the effectiveness of the used procedure in eliciting aggression. Patients' responses were not influenced by the level of social provocation, although in both groups aggression was higher after lost compared to won trials. Physiologically, controls showed fewer but higher EDA amplitudes when responding aggressively, whereas patients displayed the opposite pattern of more but lower EDA amplitudes. The modified Taylor Aggression Paradigm successfully elicited aggression and revealed different behavioral and neurophysiological responses in patients and healthy controls. Patients' aggressive behavior as well as their physiological responses were less modulated by level of provocation compared to controls. Therapeutic attempts for patients might concentrate on improving empathic abilities and the understanding of social situations, including provocation and aggressive behavior.

Neural circuitry of abdominal pain-related fear learning and reinstatement in irritable bowel syndrome

BACKGROUND

Altered pain anticipation likely contributes to disturbed central pain processing in chronic pain conditions like irritable bowel syndrome (IBS), but the learning processes shaping the expectation of pain remain poorly understood. We assessed the neural circuitry mediating the formation, extinction, and reactivation of abdominal pain-related memories in IBS patients compared to healthy controls (HC) in a differential fear conditioning paradigm.

METHODS

During fear acquisition, predictive visual cues (CS(+)) were paired with rectal distensions (US), while control cues (CS(-)) were presented unpaired. During extinction, only CSs were presented. Subsequently, memory reactivation was assessed with a reinstatement procedure involving unexpected USs. Using functional magnetic resonance imaging, group differences in neural activation to CS(+) vs CS(-) were analyzed, along with skin conductance responses (SCR), CS valence, CS-US contingency, state anxiety, salivary cortisol, and alpha-amylase activity. The contribution of anxiety symptoms was addressed in covariance analyses.

KEY RESULTS

Fear acquisition was altered in IBS, as indicated by more accurate contingency awareness, greater CS-related valence change, and enhanced CS(+)-induced differential activation of prefrontal cortex and amygdala. IBS patients further revealed enhanced differential cingulate activation during extinction and greater differential hippocampal activation during reinstatement. Anxiety affected neural responses during memory formation and reinstatement.

CONCLUSIONS & INFERENCES

Abdominal pain-related fear learning and memory processes are altered in IBS, mediated by amygdala, cingulate cortex, prefrontal areas, and hippocampus. Enhanced reinstatement may contribute to hypervigilance and central pain amplification, especially in anxious patients. Preventing a 'relapse' of learned fear utilizing extinction-based interventions may be a promising treatment goal in IBS.

Sympathetic Arousal during a Touch-Based Healing Ritual Predicts Increased Well-Being

Objective. There is mounting evidence that more elaborate treatment rituals trigger larger nonspecific effects. The reasons for this remain unclear. In a pilot field study, we investigated the role of psychophysiological changes during a touch-based healing ritual for improvements in subjective well-being.Methods. Heart rate, respiratory rate, and skin conductance levels (SCL) were continuously assessed in 22 subjects before, during, and after a touch-based healing ritual. Participants rated their expectations and subjective well-being was assessed before and after the ritual by the “Short Questionnaire on Current Disposition”.Results. Subjective well-being increased significantly from before to after the ritual. The analysis of psychophysiological changes revealed a significant increase in respiratory rate from baseline to ritual, while skin conductance, heart rate, and heart rate variability did not change. Increases in SCL as well as decreases in respiratory rate from baseline to ritual were significantly associated with improvements in subjective well-being. Regression analyses showed increases in SCL to be the only significant predictor of improvements in well-being.Conclusion. Higher sympathetic arousal during a touch-based healing ritual predicted improvements in subjective well-being. Results suggest the occurrence of an anticipatory stress response, that is, a state of enhanced sympathetic activity that is known to precede relaxation.

Sex differences in cognitive regulation of psychosocial achievement stress: brain and behavior

Although cognitive regulation of emotion has been extensively examined, there is a lack of studies assessing cognitive regulation in stressful achievement situations. This study used functional magnetic resonance imaging in 23 females and 20 males to investigate cognitive downregulation of negative, stressful sensations during a frequently used psychosocial stress task. Additionally, subjective responses, cognitive regulation strategies, salivary cortisol, and skin conductance response were assessed. Subjective response supported the experimental manipulation by showing higher anger and negative affect ratings after stress regulation than after the mere exposure to stress. On a neural level, right middle frontal gyrus (MFG) and right superior temporal gyrus (STG) were more strongly activated during regulation than nonregulation, whereas the hippocampus was less activated during regulation. Sex differences were evident: after regulation females expressed higher subjective stress ratings than males, and these ratings were associated with right hippocampal activation. In the nonregulation block, females showed greater activation of the left amygdala and the right STG during stress than males while males recruited the putamen more robustly in this condition. Thus, cognitive regulation of stressful achievement situations seems to induce additional stress, to recruit regions implicated in attention integration and working memory and to deactivate memory retrieval. Stress itself is associated with greater activation of limbic as well as attention areas in females than males. Additionally, activation of the memory system during cognitive regulation of stress is associated with greater perceived stress in females. Sex differences in cognitive regulation strategies merit further investigation that can guide sex sensitive interventions for stress-associated disorders.

Low levels of estradiol are associated with elevated conditioned responding during fear extinction and with intrusive memories in daily life

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Intrusive memories can be seen as conditioned responses to trauma reminders.

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Novel conditioned-intrusion paradigm models both fear conditioning and intrusions.

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Low estradiol is related to higher conditioned responses during fear extinction.

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Low estradiol is related to higher intrusive memory strength in daily life.

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Conditioned responding during extinction partially explains the latter relationship.

Posttraumatic stress disorder (PTSD) can be conceptualized as a disorder of emotional memory showing strong (conditioned) responses to trauma reminders and intrusive memories among other symptoms. Women are at greater risk of developing PTSD than men. Recent studies have demonstrated an influence of ovarian steroid hormones in both fear conditioning and intrusive memory paradigms. However, although intrusive memories are considered non-extinguished emotional reactions to trauma reminders, none of the previous studies has investigated effects of ovarian hormones on fear conditioning mechanisms and intrusive memories in conjunction. This may have contributed to an overall inconsistent picture of the role of these hormones in emotional learning and memory. To remedy this, we exposed 37 healthy women with a natural menstrual cycle (during early follicular or luteal cycle phase) to a novel conditioned-intrusion paradigm designed to model real-life traumatic experiences. The paradigm included a differential fear conditioning procedure with short violent film clips as unconditioned stimuli. Intrusive memories about the film clips were assessed ambulatorily on subsequent days. Women with lower levels of estradiol displayed elevated differential conditioned skin conductance responding during fear extinction and showed stronger intrusive memories. The inverse relationship between estradiol and intrusive memories was at least partially accounted for by the conditioned responding observed during fear extinction. Progesterone levels were not associated with either fear acquisition/extinction or with intrusive memories. This suggests that lower levels of estradiol might promote stronger symptoms of PTSD through associative processes.

Autonomic arousal during actigraphically estimated waking and sleep in male veterans with PTSD

Physiological hyperarousal is manifested acutely by increased heart rate, decreased respiratory sinus arrhythmia, and increased skin conductance level and variability. Yet it is uncertain to what extent such activation occurs with the symptomatic hyperarousal of posttraumatic stress disorder (PTSD). We compared 56 male veterans with current PTSD to 54 males who never had PTSD. Subjects wore ambulatory devices that recorded electrocardiograms, finger skin conductance, and wrist movement while in their normal environments. Wrist movement was monitored to estimate sleep and waking periods. Heart rate, but not the other variables, was elevated in subjects with PTSD equally during waking and during actigraphic sleep (effect sizes, Cohen's d, ranged from 0.63 to 0.89). The length of the sleep periods and estimated sleep fragmentation did not differ between groups. Group heart rate differences could not be explained by differences in body activity, PTSD hyperarousal symptom scores, depression, physical fitness, or antidepressant use.

Prereactivation propranolol fails to reduce skin conductance reactivity to prepared fear-conditioned stimuli

Pharmacologic blockade of memory reconsolidation has been demonstrated in fear-conditioned rodents and humans and may provide a means to reduce fearfulness in anxiety disorders and posttraumatic stress disorder. Studying the efficacy of potential interventions in clinical populations is challenging, creating a need for paradigms within which candidate reconsolidation-blocking interventions can be readily tested. We used videos of biologically prepared conditioned stimuli (tarantulas) to test the efficacy of propranolol in blocking reconsolidation of conditioned fear in healthy young adults. Strong differential conditioning, measured by skin conductance, was observed among a screened subset of participants during acquisition. However, subsequent propranolol failed to reduce reactivity to the reactivated conditioned stimulus. These results are consistent with other recent findings and point to a need for testing other candidate drugs.

A head-to-head comparison of SCRalyze and Ledalab, two model-based methods for skin conductance analysis

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Comparison of two developed methods for model-based analysis of phasic skin conductance responses.

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Four datasets are used to compare predictive validity.

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SCRalyze shows higher predictive validity than Ledalab in 4 of 5 comparisons, and equal predictive validity in the fifth.

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SCRalyze shows higher predictive validity than peak-scoring in all comparisons.

Model-based analysis of skin conductance responses (SCR) can furnish less noisy estimates of sympathetic arousal (SA) than operational peak scoring approaches, as shown in previous work. Here, I compare two model-based methods for analysis of evoked (stimulus-locked) SCR, implemented in two software packages, SCRalyze and Ledalab, with respect to their sensitivity in recovering SA. Four datasets are analysed to compare predictive validity, i.e. the sensitivity to distinguish pairs of SA states that are known to be different. SCRalyze was significantly better able than Ledalab to recover this known difference in four out of five tested contrasts and comparable in the remaining one. SCRalyze performed significantly better than conventional analysis in all contrasts. I conclude that the model-based method engendered in SCRalyze is currently the best available approach to provide robust and sensitive estimates of sympathetic arousal.