Hemodynamic and electrocortical reactivity to specific scene contents in emotional perception

Emotional scene perception is characterized by enhanced neural activity across broad regions of visual cortex, the frontoparietal network, and anterior corticolimbic structures. In human fMRI and electrocortical experiments, activation enhancement is strongly related to self‐reported emotional arousal evoked by scene stimuli. However, an additional bias in reaction to pleasant scenes has been reported in a subset of emotion‐enhanced brain regions. Human fMRI and primate electrophysiological studies show biased frontoparietal network activity in response to rewarding cues. In addition, activation in lateral occipital regions may show a bias in pleasant scene perception, as shown in fMRI and in the early posterior negativity (EPN) ERP component. To define this potential pleasure bias, we presented a balanced set of naturalistic scenes to participants during separate fMRI and ERP recording sessions. Consistent with past work, the amplitude of the slow‐wave late positive potential (LPP), as well as hemodynamic activity in fusiform gyrus and amygdala, showed equivalent enhancement across highly arousing pleasant and unpleasant, relative to neutral scenes. In addition to this emotional enhancement, the EPN component, as well as hemodynamic activity in lateral occipital cortex and frontoparietal network, showed greater reactivity during highly arousing pleasant relative to unpleasant scenes, consistent with a pleasure bias. The interpretation of this pattern of reactivity is discussed with respect to selective and evolved attention mechanisms.     

Shyness and emotional face processing in schizophrenia: An ERP study

Shyness in healthy controls has been related to early event-related potential (ERP) responses to emotional faces. Patients with schizophrenia typically demonstrate increased shyness that is stable and related to reduced social functioning. We indexed early ERP responses to emotional faces in relation to shyness in 40 outpatients with schizophrenia and 39 healthy controls. Patients with low-to-medium shyness showed reductions in P100 amplitude to emotional compared to neutral faces as shyness increased. Patients reporting medium-to-high shyness demonstrated the opposite pattern; P100 amplitude sharply increased as shyness increased, possibly reflecting heightened vigilance. When a restricted range of shyness scores was used to equalize scores between groups, patients showed increased N170 amplitude to emotional faces as shyness increased, whereas controls demonstrated the opposite pattern. The implications of the findings are discussed with respect to informing vulnerability to social functioning impairment and psychosocial stress in this population.     

K-complexes are not preferentially evoked to combat sounds in combat-exposed Vietnam veterans with and without post-traumatic stress disorder

The primary objective was to compare the evoked K-complex response to salient versus non-salient auditory stimuli in combat-exposed Vietnam veterans with and without post-traumatic stress disorder (PTSD). Three categories of auditory stimuli (standard 1000Hz tones, trauma-related combat sounds, and affectively neutral environmental sounds) were presented during stage 2 sleep utilizing an oddball paradigm with probabilities of occurrence of 60%, 20% and 20% respectively. Twenty-four combat-exposed Vietnam veterans, 14 with PTSD and 10 without PTSD were studied in a sleep laboratory at the National Center for PTSD in Menlo Park, CA. While significantly fewer K-complexes overall were elicited in patients, there were no differences in the proportion of K-complexes elicited by tones and combat stimuli within either group. Patients produced significantly more K-complexes to neutral stimuli than to tone or combat stimuli. Examination of the N550 component of the evoked K-complex revealed significantly longer latencies in the patient group. Across the entire sample, N550 latencies were longer for combat stimuli relative to tone neutral stimuli. There were no group or stimulus category differences for N550 amplitude. The results suggest that salient information, as defined by trauma-related combat sounds, did not preferentially elicit K-complexes in either the PTSD group or the control group, suggesting that K-complexes function to protect sleep more than to endogenously process meaningful stimuli.     

A common neural substrate for elevated PTSD symptoms and reduced pulse rate variability in combat-exposed veterans

Previous studies have identified reduced heart rate variability (HRV) in post-traumatic stress disorder (PTSD), which may temporally precede the onset of the disorder. A separate line of functional neuroimaging research in PTSD has consistently demonstrated hypoactivation of the ventromedial prefrontal cortex (vmPFC), a key aspect of a descending neuromodulatory system that exerts inhibitory control over heart rate. No research to date, however, has simultaneously investigated whether altered vmPFC activation is associated with reduced HRV and elevated PTSD symptoms in the same individuals. Here, we collected fMRI data during alternating conditions of threat of shock and safety from shock in 51 male combat-exposed veterans with either high or low levels of PTSD symptoms. Pulse rate variability (PRV)—a HRV surrogate calculated from pulse oximetry—was assessed during a subsequent resting scan. Correlational analyses tested for hypothesized relationships between reduced vmPFC activation, lower PRV, and elevated PTSD symptomatology. We found that PTSD re-experiencing symptoms were inversely associated with high-frequency (HF)-PRV, thought to primarily reflect parasympathetic control of heart rate, in veterans with elevated PTSD symptoms. Reduced vmPFC activation for the contrast of safety-threat was associated both with lower HF-PRV and elevated PTSD re-experiencing symptoms. These results tie together previous observations of reduced HRV/PRV and impaired vmPFC function in PTSD and call for further research on reciprocal brain-body relationships in understanding PTSD pathophysiology.     

Developmental trajectory of the late positive potential: Using temporal-spatial PCA to characterize within-subject developmental changes in emotional processing

The late positive potential (LPP) is characterized by temporal and spatial changes across development—though existing work has primarily relied on visual or statistical comparisons of relatively few electrodes and averaged activity over time. The current study used an empirically based approach to characterize temporal and spatial changes in ERPs over time. Data were utilized from a large longitudinal study (N = 380) in which the LPP was recorded to pleasant, neutral, and unpleasant pictures around age 9 and again around age 12. Age 9 ERPs were subtracted from age 12 ERPs for all three image types; the resulting ERPs for each subject at each electrode site were then submitted to a temporospatial principal component analysis (PCA). A PCA factor was greater in amplitude for emotional pictures compared to neutral pictures between ages 9 and 12, evident as an occipital negativity and frontocentral positivity that peaked approximately 850 ms following picture presentation. Furthermore, the factor scores to emotional pictures for this component increased as a function of age 12 pubertal development, consistent with the notion that the LPP shifts from occipital to more frontocentral sites in relation to developmental changes from childhood to adolescence. A similar factor was observed when PCA was applied to all ERPs from both ages 9 and 12. Using temporospatial PCA on ERPs collected from the same subjects over time—especially within-subject subtraction-based ERPs—provides a concise way of characterizing and quantifying within-subject developmental changes in both the timing and scalp distribution of ERPs.     

Stability and change in emotional processing across development: A 6‐year longitudinal investigation using event‐related potentials

ERPs reveal the temporal dynamics of emotional processing and are easily assessed in children. Yet, little longitudinal research has examined ERPs sensitive to emotion across development. We aimed to systematically identify timing and spatial distributions of ERPs sensitive to emotion in a longitudinal sample of youth (N = 62) using principal component analysis (PCA) and evaluate stability and change in emotional responses across development. Participants completed an emotional interrupt paradigm in childhood (M_age = 9.38, SD = 0.42), early adolescence (M_age = 13.03, SD = 0.24), and midadolescence (M_age = 15.16, SD = 0.17). ERPs were recorded to unpleasant, pleasant, and neutral images. Participants were instructed to respond to a target while viewing images. Two components sensitive to emotion emerged across development: P300/early late positive potential (LPP) and late LPP. The P300/early LPP component was characterized by an enhanced positivity for unpleasant compared to pleasant and neutral images. The late LPP was enhanced for both unpleasant and pleasant compared to neutral images, and more positive for unpleasant compared to pleasant images. The components showed moderate to strong stability. Overall LPP magnitude decreased from childhood into adolescence. There was a developmental shift in distributions from occipital sites in childhood to centroparietal sites in midadolescence. Results support use of PCA to inform scoring windows and electrode selection. The shift in distribution may reflect developmental focalization in underlying neural circuitry. Future work is needed using multimodal approaches to further understand the relationship between ERPs and changes in neural circuitry across development.     

A longitudinal examination of peritraumatic emotional responses and their association with posttraumatic stress disorder and major depressive disorder among veterans

Research has revealed a significant association between several peritraumatic emotional responses and posttraumatic stress disorder (PTSD). Preliminary research has also linked peritraumatic emotional responses with a diagnosis of major depressive disorder (MDD). The majority of this research has been cross-sectional, thereby making it difficult to determine the extent to which the various peritraumatic emotional responses may increase risk for, or serve as a premorbid marker of, PTSD and MDD. This study examined the longitudinal role of peritraumatic emotional responses on the subsequent development of PTSD and MDD in a sample of US military veterans. Whereas a number of peritraumatic emotional responses were concurrently associated with PTSD, only peritraumatic numbness maintained the association with this diagnosis longitudinally. For MDD, peritraumatic numbness was the only emotional response related to the diagnosis both concurrently and longitudinally. Study findings are a preliminary proof of concept that peritraumatic numbness may serve as a premorbid marker for the development of PTSD and MDD following a traumatic event. Implications of these findings for the diagnosis, assessment, and treatment of both PTSD and MDD are discussed.     

Time will tell: Object categorization and emotional engagement during processing of degraded natural scenes

The aim of the present study was to examine the relationship between object categorization in natural scenes and the engagement of cortico‐limbic appetitive and defensive systems (emotional engagement) by manipulating both the bottom‐up information and the top‐down context. Concerning the bottom‐up information, we manipulated the computational load by scrambling the phase of the spatial frequency spectrum, and asked participants to classify natural scenes as containing an animal or a person. The role of the top‐down context was assessed by comparing an incremental condition, in which pictures were progressively revealed, to a condition in which no probabilistic relationship existed between each stimulus and the following one. In two experiments, the categorization and response to emotional and neutral scenes were similarly modulated by the computational load. The Late Positive Potential (LPP) was affected by the emotional content of the scenes, and by categorization accuracy. When the phase of the spatial frequency spectrum was scrambled by a large amount (>58%), chance categorization resulted, and affective LPP modulation was eliminated. With less degraded scenes, categorization accuracy was higher (.82 in Experiment 1, .86 in Experiment 2) and affective modulation of the LPP was observed at a late window (>800 ms), indicating that it is possible to delay the time of engagement of the motivational systems which are responsible for the LPP affective modulation. The present data strongly support the view that semantic analysis of visual scenes, operationalized here as object categorization, is a necessary condition for emotional engagement at the electrocortical level (LPP).     

Cardiac awareness and autonomic cardiac reactivity during emotional picture viewing and mental stress

This study investigated the relationship between autonomic cardiovascular reactivity and cardiac awareness during the following conditions: baseline, emotional picture viewing, mental stress, and heartbeat tracking. Cardiac parameters were examined by using power spectrum analysis of heart rate variability and impedance cardiography. According to their performance in a heartbeat tracking task, 38 participants were classified as good (n=19) or poor (n=19) heartbeat perceivers. Neither group differed during baseline and heartbeat tracking, but good compared to poor heartbeat perceivers demonstrated greater sympathetic reactivity during mental stress and more vagal reactivity and subjective arousal during emotional picture viewing. The results suggest that cardiac awareness is related to greater responsivity of the autonomic nervous system during situations evoking autonomic reactivity.     

Heart rate variability and its neural correlates during emotional face processing in social anxiety disorder

The monitoring and regulation of one's own physiological reactions and cardioregulatory abnormalities are central to the aetiology and maintenance of social anxiety disorder (SAD). We therefore explored the neural correspondences of these heart rate alterations.     

Convergence of fMRI and ERP measures of emotional face processing in combat‐exposed U. S. military veterans

The late positive potential (LPP) and fMRI blood‐oxygen‐level dependent (BOLD) activity can provide complementary measures of the processing of affective and social stimuli. Separate lines of research using these measures have often employed the same stimuli, paradigms, and samples; however, there remains relatively little understanding of the way in which individual differences in one of these measures relates to the other, and all prior research has been conducted in psychiatrically healthy samples and using emotional scenes (not faces). Here, 32 combat‐exposed U. S. military veterans with varying levels of posttraumatic stress symptomatology viewed affective social stimuli (angry, fearful, and happy faces) and geometric shapes during separate EEG and fMRI BOLD recordings. Temporospatial principal component analysis was used to quantify the face‐elicited LPP in a data‐driven manner, prior to conducting whole‐brain correlations between resulting positivities and fMRI BOLD elicited by faces. Participants with larger positivities to fearful faces (> shapes) showed increased activation in the amygdala; larger positivities to angry and happy faces (> shapes) were associated with increased BOLD activation in the posterior fusiform gyrus and inferior temporal gyrus, respectively. Across all face types, larger positivities were associated with increased activation in the fusiform “face” area. Correlations using mean area amplitude LPPs showed an association with increased activation in the anterior insula for angry faces (> shapes). LPP‐BOLD associations were not moderated by PTSD. Findings provide the first evidence of correspondence between face‐elicited LPP and BOLD activation across a range of (normal to disordered) psychiatric health.     

Response processing during visual search in normal aging: The need for more time to prevent cross talk between spatial attention and manual response selection

It is still not well known whether the age-related behavioural slowing observed during visual search is due to changes in the allocation of attention, in response activation patterns, or to a combination of both. To help in clarifying it, attention-related (N2 posterior contralateral; N2pc, and N2 central contralateral; N2cc) and response-related (Motor Potential; MP, and Reafferent Potential; RAP) event-related potentials (ERPs) were obtained in healthy young and older participants executing a visual search task. Age was associated with N2pc and N2cc longer latencies, earlier MP onsets and longer MP rise times. Lower N2pc, higher MP and lower RAP amplitudes were also observed. Results suggest that older participants need more time to allocate spatial attention onto the target (N2pc) and to prevent cross talk between response selection and attention direction (N2cc), and that they are slower and need higher cortical activation when preparing and executing correctly selected responses (MP).     

Reciprocal relations between work stress and insomnia symptoms: A prospective study

Work stress and poor sleep are closely related in cross‐sectional data, but evidence from prospective data is limited. We analysed how perceived stress and work stressors (work demands, decision authority and workplace social support) are related to key dimensions of insomnia over time, using structural equation modelling. Biennial measurements from a large sample of the working population in Sweden enabled us to analyse both the relationship from stress to sleep as well as that from sleep to stress. Overall, we found reciprocal relations between insomnia and all four stress measures. However, looking at the relation between each dimension of insomnia and each stress measure, there were some differences in direction of effects. In the direction from stress to sleep, all work stressors as well as perceived stress predicted both difficulties initiating sleep and difficulties maintaining sleep. The same was found for non‐restorative sleep, with the exception for decision authority. In the opposite direction, difficulties maintaining sleep predicted increased levels of work demands and perceived stress. Difficulties initiating sleep stood out among the insomnia symptoms as not predicting any of the stress measures, while non‐restorative sleep was the only symptom predicting all stress measures. The results advance the understanding of the stress?sleep relationship and indicate a potential vicious circle between insomnia and perceived stress as well as work stressors, suggesting that the workplace could be an arena for interventions to alleviate insomnia.     

Cognitive functioning and emotion processing in breast cancer survivors and controls: An ERP pilot study

Diagnosis and treatment of breast cancer is a very emotionally aversive and stressful life event, which can lead to impaired cognitive functioning and mental health. Breast cancer survivors responding with repressive emotion regulation strategies often show less adaptive coping and adverse outcomes. We investigated cognitive functioning and neural correlates of emotion processing using ERPs. Self‐report measures of depression, anxiety, and fatigue, as well as hair cortisol as an index of chronic stress, were assessed. Twenty breast cancer survivors (BCS) and 31 carefully matched healthy controls participated in the study. After neuropsychological testing and subjective assessments, participants viewed 30 neutral, 30 unpleasant, and 30 pleasant pictures, and ERPs were recorded. Recognition memory was tested 1 week later. BCS reported stronger complaints about cognitive impairments and more symptoms of depression, anxiety, and fatigue. Moreover, they showed elevated hair cortisol levels. Except for verbal memory, cognitive functioning was predominantly in the normative range. Recognition memory performance was decreased in cancer survivors, especially for emotional contents. In ERPs, survivors showed smaller late positive potential amplitudes for unpleasant pictures relative to controls in a later time window, which may indicate less elaborative processing of this material. Taken together, we found cognitive impairments in BCS in verbal memory, impaired emotional picture memory accuracy, and reduced neural activity when breast cancer survivors were confronted with unpleasant materials. Further studies and larger sample sizes, however, are needed to evaluate the relationship between altered emotion processing and reduced memory in BCS in order to develop new treatment strategies.     

Effects of concurrent working memory load on distractor and conflict processing in a name‐face Stroop task

To examine the time course of effects of working memory (WM) load on interference control, ERPs were measured in a combined WM and Stroop task. A WM load of 0, 2, or 4 letters was imposed, and during the maintenance‐interval Stroop trials were presented that required participants to classify names of famous people while ignoring faces that were either congruent or incongruent with the names. Behavioral interference was not modulated by WM load, but WM load led to an overall reduction of Stroop stimulus encoding as reflected by reduced N170 and N250 amplitudes independent of congruency. Incongruent distractor faces induced interference as shown by a delayed and reduced positivity between 480–600 ms (N450) and an enhanced positivity between 760–1000 ms (P600), indicating longer stimulus evaluation, conflict detection, and conflict resolution, respectively. WM load led to an increase of the P600 at frontal and parietal sites, possibly reflecting PFC‐driven top‐down control of posterior sites, necessary for conflict resolution.     

An exploration of the relationship between voices,dissociation, and post-traumatic stress disorder symptoms

Objectives

Extensive research has shown voice hearing to be associated with symptoms of Post-Traumatic Stress Disorder (PTSD) and dissociation. However, most studies have adopted a quantitative design, using cross-sectional data sampling methods, precluding temporal relationships between variables from being defined.

Design

Using a qualitative design, this study sought to identify potential symptom relationships by addressing the research question: what is the nature of the temporal relationship between voices, dissociation and PTSD symptoms?

Methods

Seven voice hearers (aged 27 to 68 years) participated in a semi-structured interview exploring voice hearing, PTSD symptoms, and dissociation. The interviews were analysed using Interpretative Phenomenological Analysis.

Results

One superordinate theme was identified in the data. Voices were observed to occur in dynamic interrelationship with PTSD symptoms and dissociation, and were frequently experienced before and after PTSD symptoms and dissociative episodes.

Conclusions

Implications for theoretical understandings of voice hearing and future research are discussed.