Showing papers in "Psychophysiology in 2015"

The reward positivity: From basic research on reward to a biomarker for depression

Abstract: Feedback indicating monetary loss elicits an apparent negative deflection in the event-related potential (ERP) that has been referred to as the feedback error-related negativity, medial frontal negativity, feedback-related negativity, and feedback negativity-all conceptualizations that suggest a negative ERP component that is greater for loss than gain. In the current paper, I review a programmatic line of research indicating that this apparent negativity actually reflects a reward-related positivity (RewP) that is absent or suppressed following nonreward. I situate the RewP within a broader nomological network of reward processing and individual differences in sensitivity to rewards. Further, I review work linking reductions in the RewP to increased depressive symptoms and risk for depression. Finally, I discuss future directions for research on the RewP.

A multifaceted investigation of the link between mental fatigue and task disengagement

Abstract: Mental fatigue is often characterized by reduced motivation for effortful activity and impaired task performance. We used subjective, behavioral (performance), and psychophysiological (P3, pupil diameter) measures during an n-back task to investigate the link between mental fatigue and task disengagement. After 2 h, we manipulated the rewards to examine a possible reengagement effect. Analyses showed that, with increasing fatigue and time-on-task, performance, P3 amplitude, and pupil diameter decreased. After increasing the rewards, all measures reverted to higher levels. Multilevel analysis revealed positive correlations between the used measures with time-on-task. We interpret these results as support for a strong link between task disengagement and mental fatigue.

How inappropriate high‐pass filters can produce artifactual effects and incorrect conclusions in ERP studies of language and cognition

Abstract: Although it is widely known that high-pass filters can reduce the amplitude of slow ERP components, these filters can also introduce artifactual peaks that lead to incorrect conclusions. To demonstrate this and provide evidence about optimal filter settings, we recorded ERPs in a typical language processing paradigm involving syntactic and semantic violations. Unfiltered results showed standard N400 and P600 effects in the semantic and syntactic violation conditions, respectively. However, high-pass filters with cutoffs at 0.3 Hz and above produced artifactual effects of opposite polarity before the true effect. That is, excessive high-pass filtering introduced a significant N400 effect preceding the P600 in the syntactic condition, and a significant P2 effect preceding the N400 in the semantic condition. Thus, inappropriate use of high-pass filters can lead to false conclusions about which components are influenced by a given manipulation. The present results also lead to practical recommendations for high-pass filter settings that maximize statistical power while minimizing filtering artifacts.

It's not too late: the onset of the frontocentral P3 indexes successful response inhibition in the stop-signal paradigm.

Abstract: The frontocentral P3 event-related potential has been proposed as a neural marker of response inhibition. However, this association is disputed: some argue that P3 latency is too late relative to the timing of action stopping (stop-signal reaction time; SSRT) to index response inhibition. We tested whether P3 onset latency is a marker of response inhibition, and whether it coincides with the timing predicted by neurocomputational models. We measured EEG in 62 participants during the stop-signal task, and used independent component analysis and permutation statistics to measure the P3 onset in each participant. We show that P3 onset latency is shorter when stopping is successful, that it is highly correlated with SSRT, and that it coincides with the purported timing of the inhibition process (towards the end of SSRT). These results demonstrate the utility of P3 onset latency as a noninvasive, temporally precise neural marker of the response inhibition process.

Regression-based estimation of ERP waveforms: I. The rERP framework.

Abstract: ERP averaging is an extraordinarily successful method, but can only be applied to a limited range of experimental designs. We introduce the regression-based rERP framework, which extends ERP averaging to handle arbitrary combinations of categorical and continuous covariates, partial confounding, nonlinear effects, and overlapping responses to distinct events, all within a single unified system. rERPs enable a richer variety of paradigms (including high-N naturalistic designs) while preserving the advantages of traditional ERPs. This article provides an accessible introduction to what rERPs are, why they are useful, how they are computed, and when we should expect them to be effective, particularly in cases of partial confounding. A companion article discusses how nonlinear effects and overlap correction can be handled within this framework, as well as practical considerations around baselining, filtering, statistical testing, and artifact rejection. Free software implementing these techniques is available.

Teasing apart the anticipatory and consummatory processing of monetary incentives: An event-related potential study of reward dynamics.

Abstract: The monetary incentive delay (MID) task has been widely used in fMRI studies to investigate the neural networks involved in anticipatory and consummatory reward processing. Previous efforts to adapt the MID task for use with ERPs, however, have had limited success. Here, we sought to further decompose reward dynamics using a comprehensive set of anticipatory (cue-N2, cue-P3, contingent negative variation [CNV]) and consummatory ERPs (feedback negativity [FN], feedback P3 [fb-P3]). ERP data was recorded during adapted versions of the MID task across two experiments. Unlike previous studies, monetary incentive cues modulated the cue-N2, cue-P3, and CNV; however, cue-related ERPs and the CNV were uncorrelated with one another, indicating distinct anticipatory subprocesses. With regard to consummatory processing, FN amplitude primarily tracked outcome valence (reward vs. nonreward), whereas fb-P3 amplitude primarily tracked outcome salience (uncertain vs. certain). Independent modulation of the cue-P3 and fb-P3 was observed, indicating that these two P3 responses may uniquely capture the allocation of attention during anticipatory and consummatory reward processing, respectively. Overall, across two samples, consistent evidence of both anticipatory and consummatory ERP activity was observed on an adapted version of the MID paradigm, demonstrating for the first time how these ERP components may be integrated with one another to more fully characterize the time course of reward processing. This ERP-MID paradigm is well suited to parsing reward dynamics, and can be applied to both healthy and clinical populations.

Revisiting the incremental effects of context on word processing: Evidence from single‐word event‐related brain potentials

Abstract: The amplitude of the N400-an event-related potential (ERP) component linked to meaning processing and initial access to semantic memory-is inversely related to the incremental buildup of semantic context over the course of a sentence. We revisited the nature and scope of this incremental context effect, adopting a word-level linear mixed-effects modeling approach, with the goal of probing the continuous and incremental effects of semantic and syntactic context on multiple aspects of lexical processing during sentence comprehension (i.e., effects of word frequency and orthographic neighborhood). First, we replicated the classic word-position effect at the single-word level: Open-class words showed reductions in N400 amplitude with increasing word position in semantically congruent sentences only. Importantly, we found that accruing sentence context had separable influences on the effects of frequency and neighborhood on the N400. Word frequency effects were reduced with accumulating semantic context. However, orthographic neighborhood was unaffected by accumulating context, showing robust effects on the N400 across all words, even within congruent sentences. Additionally, we found that N400 amplitudes to closed-class words were reduced with incrementally constraining syntactic context in sentences that provided only syntactic constraints. Taken together, our findings indicate that modeling word-level variability in ERPs reveals mechanisms by which different sources of information simultaneously contribute to the unfolding neural dynamics of comprehension.

Updating and validating a new framework for restoring and analyzing latency‐variable ERP components from single trials with residue iteration decomposition (RIDE)

Abstract: Trial-to-trial latency variability pervades cognitive EEG responses and may mix and smear ERP components but is usually ignored in conventional ERP averaging. Existing attempts to decompose temporally overlapping and latency-variable ERP components show major limitations. Here, we propose a theoretical framework and model of ERPs consisting of temporally overlapping components locked to different external events or varying in latency from trial to trial. Based on this model, a new ERP decomposition and reconstruction method was developed: residue iteration decomposition (RIDE). Here, we describe an update of the method and compare it to other decomposition methods in simulated and real datasets. The updated RIDE method solves the divergence problem inherent to previous latency-based decomposition methods. By implementing the model of ERPs as consisting of time-variable and invariable single-trial component clusters, RIDE obtains latency-corrected ERP waveforms and topographies of the components, and yields dynamic information about single trials.

Focusing neurovisceral integration: cognition, heart rate variability, and cerebral blood flow.

Abstract: The neurovisceral integration hypothesis suggests in part that cerebral control of autonomic function conveys comparable control of executive function and, hence, correlation among vagally determined high frequency heart rate variability (HF-HRV), executive function, and regional cerebral blood flow (CBF). In 440 middle-aged men and women, resting HF-HRV was related to regional CBF derived from a resting arterial spin-labeled MRI scan and to seven neuropsychological tests of executive function. Despite some intercorrelations, regression modeling failed to support integrated central control of HF-HRV and executive function. Integration between autonomic and cognitive control appears more circumscribed than the general integration suggested by the neurovisceral integration hypothesis.

Time-frequency theta and delta measures index separable components of feedback processing in a gambling task

Abstract: Previous work using gambling tasks indicate that the feedback negativity (FN) reflects primary or salient stimulus attributes (often gain vs. loss), whereas the feedback-P300 appears sensitive to secondary stimulus information. A recent time-frequency approach has characterized separable theta (3–7 Hz) and delta (0–3 Hz) feedback processes, independently sensitive to primary feedback attributes, specifically loss and gain outcomes, respectively. The current study extends this time-frequency work to evaluate both primary and secondary (relative outcome and outcome magnitude) feedback attributes. Consistent with previous reports, theta indexed an initial, lower-level response sensitive to the primary (most salient) feedback attributes (specifically losses), while delta was sensitive to both primary attributes (specifically gains) and assessed secondary stimulus features.

When flanker meets the n-back: What EEG and pupil dilation data reveal about the interplay between the two central-executive working memory functions inhibition and updating

Abstract: We investigated the interplay between inhibition and updating, two executive working memory (WM) functions. We applied a novel task paradigm consisting of flanker stimuli presented within an n-back task and studied the interaction between inhibitory demands and load on WM updating using behavioral measures, EEG, and pupil dilation. In contrast to studies that examine the interaction between inhibitory demands and load on WM storage components, the current task paradigm allowed testing the interaction between the executive WM components updating and inhibition. We found a reduced flanker interference effect for the highest (2-back) updating load condition compared to lower updating load conditions on most measures. We interpret these findings as indicating that inhibitory control and WM updating are closely intertwined executive functions. Increased load on updating seemed to result in an overall more activated attentional network thus enhancing inhibitory control, such that task performance is less susceptible to distracting information.

Methodological recommendations for a heartbeat detection‐based measure of interoceptive sensitivity

Abstract: Heartbeat detection tasks are often used to measure cardiac interoceptive sensitivity-the ability to detect sensations from one's heart However, there is little work to guide decisions on the optimum number of trials to use, which should balance reliability and power against task duration and participant burden Here, 174 participants completed 100 trials of a widely used heartbeat detection task where participants attempt to detect whether presented tones occurred synchronously or asynchronously with their heartbeats First, we quantified measurement reliability of the participant's accuracy derived from differing numbers of trials of the task using a correlation metric; we found that at least 40-60 trials were required to yield sufficient reliability Next, we quantified power by simulating how the number of trials influenced the ability to detect a correlation between cardiac interoceptive sensitivity and other variables that differ across participants, including a variable measured from our sample (body mass index) as well as simulated variables of varying effect sizes Using these simulations, we quantified the trade-offs between sample size, effect size, and number of trials in the heartbeat detection task such that a researcher can easily determine any one of these variables at given values of the other two variables We conclude that using fewer than 40 trials is typically insufficient due to poor reliability and low power in estimating an effect size, although the optimal number of trials can differ by study

Regression-based estimation of ERP waveforms: II. Nonlinear effects, overlap correction, and practical considerations

Abstract: A companion paper introduced the rERP framework, which recasts traditional event-related potential (ERP) averaging as a special case of a more flexible regression-based approach to estimating ERP waveforms. Here, we build on this foundation, showing how rERP analysis can also handle the estimation of nonlinear effects (a generalization of both the well-known approach of dichotomizing continuous covariates, and also of the ERP image technique), and can disentangle overlapping ERPs to temporally adjacent stimuli. We then consider how the use of rERPs impacts on other parts of the EEG analysis pipeline, including baselining, filtering, significance testing, and artifact rejection, and provide practical recommendations. Free software implementing these techniques is available.

Modeling nonlinear relationships in ERP data using mixed-effects regression with R examples.

Abstract: In the analysis of psychological and psychophysiological data, the relationship between two variables is often assumed to be a straight line This may be due to the prevalence of the general linear model in data analysis in these fields, which makes this assumption implicitly However, there are many problems for which this assumption does not hold In this paper, we show that, in the analysis of event-related potential (ERP) data, the assumption of linearity comes at a cost and may significantly affect the inferences drawn from the data We demonstrate why the assumption of linearity should be relaxed and how to model nonlinear relationships between ERP amplitudes and predictor variables within the familiar framework of generalized linear models, using regression splines and mixed-effects modeling

Resting high-frequency heart rate variability is related to resting brain perfusion

Abstract: We examined the neural correlates of resting cardiac vagal activity in a sample of 432 participants (206 male; 61 African American; mean age 42 years). Pulsed arterial spin labeling was used to quantify whole brain and regional cerebral blood flow at rest. High-frequency heart rate variability (HF-HRV) was used to measure cardiac vagal activity at rest. The primary aim was to determine whether brain regions implicated in regulating cardiac vagal reactions were also related to cardiac vagal activity at rest, and whether these associations varied by sex or race. Brain areas previously related to vagal reactivity were related to resting HF-HRV. Directionality of relationships differed between overall and regional flows. Some relationships were only observed in women and African Americans. There appears to be communality between brain regions associated with task-induced vagal reactivity and those associated with resting cardiac vagal activity.

Estimating time-varying RSA to examine psychophysiological linkage of marital dyads.

Abstract: One of the primary tenets of polyvagal theory dictates that parasympathetic influence on heart rate, often estimated by respiratory sinus arrhythmia (RSA), shifts rapidly in response to changing environmental demands. The current standard analytic approach of aggregating RSA estimates across time to arrive at one value fails to capture this dynamic property within individuals. By utilizing recent methodological developments that enable precise RSA estimates at smaller time intervals, we demonstrate the utility of computing time-varying RSA for assessing psychophysiological linkage (or synchrony) in husband-wife dyads using time-locked data collected in a naturalistic setting.

Effect of acute exercise and cardiovascular fitness on cognitive function: an event-related cortical desynchronization study.

Abstract: This study aimed to clarify the effects of acute exercise and cardiovascular fitness on cognitive function using the Stroop test and event-related desynchronization (ERD) in an aged population. Old adults (63.10 ± 2.89 years) were first assigned to either a high-fitness or a low-fitness group, and they were then subjected to an acute exercise treatment and a reading control treatment in a counterbalanced order. Alpha ERD was recorded during the Stroop test, which was administered after both treatments.Acute exercise improved cognitive performance regardless of the level of cognition, and old adults with higher fitness levels received greater benefits from acute exercise. Additionally, acute exercise, rather than overall fitness, elicited greater lower and upper alpha ERDs relative to the control condition. These findings indirectly suggest that the beneficial effects of acute exercise on cognitive performance may result from exercise-induced attentional control observed during frontal neural excitation. Descriptors: Electroencephalography (EEG), Event-related synchronization (ERS), Executive function, Stroop test

Efficacy of paced breathing for insomnia: Enhances vagal activity and improves sleep quality

Abstract: Fourteen self-reported insomniacs (SRI) and 14 good sleepers (GS) had their cardiac neuronal activity assessed by heart rate variability (HRV) under controlled respiration at a slow frequency rate of 0.1 Hz, and a forced rate of 0.2 Hz during daytime rest. Nighttime sleep was measured by polysomnography. The SRI showed depressed high frequency power of HRV compared to the GS. An increased total power of HRV was observed among the SRI during slow, paced breathing compared with spontaneous breathing and 0.2 Hz. Sleep onset latency, number of awakenings, and awakening time during sleep were decreased and sleep efficiency was increased if SRI practiced slow, paced breathing exercises for 20 min before going to sleep. Our results indicate that there is autonomic dysfunction among insomniacs, especially in relation to vagal activity; however, this decreased vagal activity can be facilitated by practicing slow, paced breathing, thereby improving sleep quality.

You see what you have learned. Evidence for an interrelation of associative learning and visual selective attention

Abstract: Besides visual salience and observers' current intention, prior learning experience may influence deployment of visual attention. Associative learning models postulate that observers pay more attention to stimuli previously experienced as reliable predictors of specific outcomes. To investigate the impact of learning experience on deployment of attention, we combined an associative learning task with a visual search task and measured event-related potentials of the EEG as neural markers of attention deployment. In the learning task, participants categorized stimuli varying in color/shape with only one dimension being predictive of category membership. In the search task, participants searched a shape target while disregarding irrelevant color distractors. Behavioral results showed that color distractors impaired performance to a greater degree when color rather than shape was predictive in the learning task. Neurophysiological results show that the amplified distraction was due to differential attention deployment (N2pc). Experiment 2 showed that when color was predictive for learning, color distractors captured more attention in the search task (ND component) and more suppression of color distractor was required (PD component). The present results thus demonstrate that priority in visual attention is biased toward predictive stimuli, which allows learning experience to shape selection. We also show that learning experience can overrule strong top-down control (blocked tasks, Experiment 3) and that learning experience has a longer-term effect on attention deployment (tasks on two successive days, Experiment 4).

The dependability of electrophysiological measurements of performance monitoring in a clinical sample: A generalizability and decision analysis of the ERN and Pe.

Abstract: Psychometric studies of the ERN, CRN, Pe, and Pc ERPs are increasing. Coherent integration of these results is difficult with classical test theory because the definition of error depends on the measure of reliability. This study used generalizability theory, which extends the ideas of classical test theory, as a framework for evaluating the influence of psychopathology and number of trials on dependability of measurement. Participants included 34 people meeting criteria for major depression, 29 meeting criteria for an anxiety disorder, and 319 controls. For all ERPs, within-person variance was larger than between-person variance across groups, indicating many trials are needed for adequate dependability (at least 13). Slightly fewer trials were needed to achieve adequate dependability in the control group than the pathology groups. Regions of interest had higher dependability than single sensors.

A systematic review of the mismatch negativity as an index for auditory sensory memory: From basic research to clinical and developmental perspectives

Abstract: Auditory sensory memory is an important ability for successful language acquisition and processing. The mismatch negativity (MMN) in response to auditory stimuli has been proposed as an objective tool to measure the existence of auditory sensory memory traces. By increasing interstimulus intervals, attenuation of MMN peak amplitude and increased MMN peak latency have been suggested to reflect duration and decay of sensory memory traces. The aim of the present study is to conduct a systematic review of studies investigating sensory memory duration with MMN. Searches of electronic databases yielded 743 articles. Of these, 37 studies met final eligibility criteria. Results point to maturational changes in the time span of auditory sensory memory from birth on with a peak in young adulthood, as well as to a decrease of sensory memory duration in healthy aging. Furthermore, this review suggests that sensory memory decline is related to diverse neurological, psychiatric, and pediatric diseases, including Alzheimer's disease, alcohol abuse, schizophrenia, and language disorders. This review underlines that the MMN provides a unique window to the cognitive processes of auditory sensory memory. However, further studies combining electrophysiological and behavioral data, and further studies in clinical populations are needed, also on individual levels, to validate the MMN as a clinical tool for the assessment of sensory memory duration.

Single Bouts of Exercise Selectively Sustain Attentional Processes

Abstract: This study examined how single bouts of exercise may differentially modulate neuroelectric correlates of attentional orienting and processing. Using a within-participants design, ERPs and task performance were assessed in response to a perceptually challenging three-stimulus oddball task prior to and following a bout of exercise or seated rest during two separate, counterbalanced sessions. Findings revealed that, following a single bout of exercise, attentional processing was sustained relative to pretest whereas prolonged sitting resulted in attentional decrements. Focal attention resulting from attentional orienting, in contrast, does not appear to be sensitive to the influences of single bouts of physical activity. These findings suggest that acute exercise-induced changes in cognition do not originate from an overall modulation of attention but instead are specific to aspects of attentional processing.

Resting heart rate variability is associated with inhibition of conditioned fear

Abstract: Startle blink as well as skin conductance responses (SCR) are widely used indices of learning processes associated with fear conditioning and extinction. During safety learning, the amygdala is under top-down inhibitory control by the prefrontal cortex (PFC). The capacity of the PFC to exert inhibitory control over subcortical brain structures may be indexed by resting state vagally mediated heart rate variability (HRV). The present study investigated the association of resting HRV with startle blink and SCR during conditioned fear inhibition and extinction. Participants first learned to discriminate a threat cue (A) signaling an aversive unconditioned stimulus from a safety signal (B), which were each presented together with a third stimulus X (AX+/BX-). Then, both the threat and safety signal were presented together (AB) to test whether the presence of the learned safety signal inhibits the fear response to the danger signal. Finally, AX was presented without reinforcement (AX-) to investigate fear extinction. Higher HRV was associated with pronounced fear inhibition and fear extinction. Resting HRV levels were associated with fear extinction as indexed by startle blink potentiation but not SCR, which presumably reflect more cognitive aspects of learning. Resting HRV may reflect the capacity of the prefrontal cortex to inhibit subcortical fear responses in the presence of safety or when former threat cues are presented in the absence of threat.

ERP and pupil responses to deviance in an oddball paradigm.

Abstract: We investigated the relationship between, and functional significance of, P300, novelty P3, and the pupil dilation response (PDR). Subjects categorized stimuli including (a) words of a frequent category, (b) words of an infrequent category (14%), and (c) pictures of the frequent category ("novels"; 14%). The P300 and novelty P3 were uncorrelated with the PDR and differed in their response to experimental manipulation. Therefore, although the three physiological responses often co-occur, they appear to each manifest a distinct function: The PDR may be more closely linked to aspects of behavioral responding than the event-related potentials. Within participants, P300 and PDR latencies accounted for unique portions of the reaction time variance, and amplitudes of all three responses were larger for stimuli recalled on a subsequent test, compared to not recalled. We discuss the possibility that all three responses reflect norepinephric input from the locus coeruleus.

Memory, emotion, and pupil diameter: Repetition of natural scenes

Abstract: Recent studies have suggested that pupil diameter, like the "old-new" ERP, may be a measure of memory. Because the amplitude of the old-new ERP is enhanced for items encoded in the context of repetitions that are distributed (spaced), compared to massed (contiguous), we investigated whether pupil diameter is similarly sensitive to repetition. Emotional and neutral pictures of natural scenes were viewed once or repeated with massed (contiguous) or distributed (spaced) repetition during incidental free viewing and then tested on an explicit recognition test. Although an old-new difference in pupil diameter was found during successful recognition, pupil diameter was not enhanced for distributed, compared to massed, repetitions during either recognition or initial free viewing. Moreover, whereas a significant old-new difference was found for erotic scenes that had been seen only once during encoding, this difference was absent when erotic scenes were repeated. Taken together, the data suggest that pupil diameter is not a straightforward index of prior occurrence for natural scenes.

Heartbeat-related EEG amplitude and phase modulations from wakefulness to deep sleep: Interactions with sleep spindles and slow oscillations

Abstract: Based on physiological models of neurovisceral integration, different studies have shown how cognitive processes modulate heart rate and how the heartbeat, on the other hand, modulates brain activity. We tried to further determine interactions between cardiac and electrical brain activity by means of EEG. We investigated how the heartbeat modulates EEG in 23 healthy controls from wakefulness to deep sleep and showed that frontocentral heartbeat evoked EEG amplitude and phase locking (as measured by intertrial phase locking), at about 300-400 ms after the R peak, decreased with increasing sleep depth with a renewed increase during REM sleep, which underpins the assumption that the heartbeat evoked positivity constitutes an active frontocortical response to the heartbeat. Additionally, we found that individual heart rate was correlated with the frequency of the EEG's spectral peak (i.e., alpha peak frequency during wakefulness). This correlation was strongest during wakefulness and declined linearly with increasing sleep depth. Furthermore, we show that the QRS complex modulates spindle phase possibly related to the correspondence between the frequency of the QRS complex and the spindle frequency of about 12-15 Hz. Finally, during deep sleep stages, a loose temporal coupling between heartbeats and slow oscillation (0.8 Hz) could be observed. These findings indicate that cardiac activity such as heart rate or individual heartbeats can modulate or be modulated by ongoing oscillatory brain activity.

Relaxation training assisted by heart rate variability biofeedback: Implication for a military predeployment stress inoculation protocol

Abstract: Decreased heart rate variability (HRV) is associated with posttraumatic stress disorder (PTSD) and depression symptoms, but PTSD's effects on the autonomic stress response and the potential influence of HRV biofeedback in stress relaxation training on improving PTSD symptoms are not well understood. The objective of this study was to examine the impact of a predeployment stress inoculation training (PRESTINT) protocol on physiologic measures of HRV in a large sample of the military population randomly assigned to experimental HRV biofeedback-assisted relaxation training versus a control condition. PRESTINT altered the parasympathetic regulation of cardiac activity, with experimental subjects exhibiting greater HRV, that is, less arousal, during a posttraining combat simulation designed to heighten arousal. Autonomic reactivity was also found to be related to PTSD and self-reported use of mental health services. Future PRESTINT training could be appropriate for efficiently teaching self-help skills to reduce the psychological harm following trauma exposure by increasing the capacity for parasympathetically modulated reactions to stress and providing a coping tool (i.e., relaxation method) for use following a stressful situation.

Examining gender specificity of sexual response with concurrent thermography and plethysmography.

Abstract: Men's genital responses are significantly greater to sexual stimuli of their preferred gender compared to their nonpreferred gender (gender-specific), whereas androphilic (i.e., sexually attracted to men) women's genital responses are similar to sexual stimuli depicting either women or men (gender-nonspecific). This gendered pattern of genital response has only been demonstrated using vaginal photoplethysmography (VPP) in women and primarily penile plethysmography (PPG) in men. These measures assess different aspects of genital vasocongestion, thereby limiting comparisons between genders. Thermography is a newer sexual psychophysiology methodology that measures genital vasocongestion via temperature change and is better suited to assess sexual response between genders because the dependent measure, change in genital temperature, is similar for women and men. Further, previous studies have assessed gender specificity of sexual response across relatively short sexual stimuli, allowing only the examination of initial phases of sexual response. We examined gender specificity of sexual arousal by measuring women's and men's genital responses to lengthier stimuli with concurrent thermography and VPP/PPG. Gynephilic men (i.e., sexually attracted to women; n = 27) and androphilic women (n = 28) viewed 10-min films depicting men masturbating, women masturbating, and a nonsexual film, and reported feelings of sexual arousal while genital responses were assessed. Across measures, men's sexual responses were gender-specific and women's responses were gender-nonspecific, indicating that the gender difference in gender specificity of arousal is robust to methodology and stimulus duration. These findings replicate previous research, extend knowledge of gendered sexual response, and highlight the utility of multimethod approaches in sexual psychophysiology.

Personality and emotional processing: A relationship between extraversion and the late positive potential in adolescence.

Abstract: Neuroticism and extraversion are multifaceted affective-laden personality traits that have been associated with major depressive disorder (MDD). Research and theory have argued that extraversion, and particularly its facet positive emotionality, is specific to MDD, while neuroticism is common across internalizing disorders. Converging evidence has suggested that MDD is associated with reduced engagement with emotional stimuli, but it remains unclear whether either extraversion, neuroticism, or both modulate reactivity to emotional cues. The late positive potential (LPP) is an event-related brain potential that is uniquely suited to assess engagement with emotional stimuli because it reflects sustained attention toward emotional content. The current study examined the LPP in relation to personality traits that may confer risk for depression by examining the relationship between the LPP and both neuroticism and extraversion in never-depressed adolescent girls. Specifically, 550 girls aged 13.5-15.5 with no lifetime history of depression completed an emotional picture-viewing task, and the LPP was measured in response to neutral, pleasant, and unpleasant pictures. Personality traits were gathered via self- and informant report. Results indicated that high extraversion was associated with a potentiated LPP to emotional pictures-and this effect was accounted for by positive emotionality in particular. In contrast, there was no association between the LPP and neuroticism or its facets. The present study is one of the first to demonstrate that extraversion is associated with variation in neural indices of emotional picture processing, similar to what has been observed among individuals with depression and at high risk for depression.

Event-related potentials to acoustic startle probes during the anticipation of predictable and unpredictable threat.

Abstract: The startle reflex is a robust measure of defense system activation. Startle probes also elicit ERP P300 and N100 responses that capture attentional engagement. The startle probe-elicited P300 and N100 have been primarily examined during affective picture viewing paradigms, and no study has examined these measures in the context of a threat anticipation task or in relation to threat predictability. In the present study, 131 participants completed a no (N), predictable (P), and unpredictable (U) threat-of-shock task, and the startle eye blink reflex, P300, and N100 responses to the startle probe were measured. We also examined several psychometric properties of these psychophysiological measures. Results indicated probe P300 attenuation during the P and U relative to N condition. In contrast, probe N100 enhancement was present only for the U condition. The P300 and N100 decreased (i.e., habituated) at comparable rates across the different threat conditions. The startle reflex also decreased, but only startle during the U (and not P) condition continued to differ from the N condition by the end of the task. Internal consistency of the ERP measures was acceptable and comparable to the startle reflex. Finally, the startle reflex was correlated with the probe N100, but not P300, across threat conditions. This study is one of the first to use startle probe ERPs to demonstrate that a context of potential threat also elicits attentional engagement. Furthermore, this study provides novel evidence that the probe N100 may provide a measure that is uniquely sensitive to unpredictable threat.