Early affective processing in patients with acute posttraumatic stress disorder: magnetoencephalographic correlates

Reduced gray matter volume in the left prefrontal, occipital, and temporal regions as predictors for posttraumatic stress disorder: a voxel-based morphometric study

The concept of acute stress disorder (ASD) was introduced as a diagnostic entity to improve the identification of traumatized people who are likely to develop posttraumatic stress disorder (PTSD). Neuroanatomical models suggest that changes in the prefrontal cortex, amygdala, and hippocampus play a role in the development of PTSD. Using voxel-based morphometry, this study aimed to investigate the predictive power of gray matter volume (GMV) alterations for developing PTSD. The GMVs of ASD patients (n = 21) were compared to those of PTSD patients (n = 17) and healthy controls (n = 18) in whole-brain and region-of-interest analyses. The GMV alterations seen in ASD patients shortly after the traumatic event (T1) were also correlated with PTSD symptom severity and symptom clusters 4 weeks later (T2). Compared with healthy controls, the ASD patients had significantly reduced GMV in the left visual cortex shortly after the traumatic event (T1) and in the left occipital and prefrontal regions 4 weeks later (T2); no significant differences in GMV were seen between the ASD and PTSD patients. Furthermore, a significant negative association was found between the GMV reduction in the left lateral temporal regions seen after the traumatic event (T1) and PTSD hyperarousal symptoms 4 weeks later (T2). Neither amygdala nor hippocampus alterations were predictive for the development of PTSD. These data suggest that gray matter deficiencies in the left hemispheric occipital and temporal regions in ASD patients may predict a liability for developing PTSD.

Rapid brain responses to affective pictures indicate dimensions of trauma-related psychopathology in adolescents

A variety of mental disorders are related to deviant brain activity, but these neural alterations do not validate psychiatric diagnostic categories. High symptom overlap and variable symptom patterns encourage a dimensional approach. Following the logic of the Research Domain Criteria (RDoC), we investigated trauma survivors for symptom clusters that might be associated with characteristics of ERPs, in particular with the early posterior negativity (EPN) elicited during affective picture processing. In rapid serial visual presentation, 90 adolescents (40 male/50 female, age M = 15.0 ± 2.5 years) who had been exposed to varying amounts of traumatic stress passively viewed a stream of high‐arousing positive and low‐arousing neutral pictures taken from the International Affective Picture System (IAPS). Using standardized interviews, symptoms of trauma‐related mental disorders were assessed (including those for PTSD, depression, borderline personality disorder, and behavioral problems). A principal component analysis was performed to derive potential dimensions of psychopathology. Multiple regression analysis confirmed a factor comprising problems concentrating, sleeping difficulties, and mistrust as a predictor of a larger EPN difference between high‐arousing positive and low‐arousing neutral IAPS pictures (β = 0.19, p < 0.05). Sex predicted the magnitude of the EPN (β = 0.45, p < 0.001). Male adolescents displayed a stronger EPN suppression than female adolescents. The result suggests that problems concentrating, sleeping difficulties, and mistrust seem to be trans‐diagnostic elements related to diminished early emotional discrimination represented by the EPN. Furthermore, our findings indicate that the EPN in response to emotional processing is modulated by sex.

Based on the RDoC heuristic, symptom clusters that may be associated with the early posterior negativity (EPN) elicited during affective picture processing were investigated in youth trauma survivors. Analysis confirmed a factor comprising problems concentrating, sleeping difficulties, and mistrust as a predictor of a larger EPN difference between high arousing positive and low arousing neutral IAPS pictures using rapid serial visual presentation (RSVP). The EPN component was also modulated by sex. The findings also extend those of prior research on emotional processing confirming that EPN suppression can also be found in adolescents.

Biased emotional attention in patients with dental phobia

Biased motivated attention towards phobia-relevant pictures is a typical finding in specific phobia. In the visual system, the allocation of motivated attention is indexed by two event-related potential components - the Early Posterior Negativity and the Late Positive Potential. Enhanced Early Posterior Negativity and Late Positive Potential amplitudes are reliably observed in specific phobia such as, for instance, snake, spider, or blood-injection-injury phobia and to some extent also in dental phobia. However, regarding dental phobia results are sparse and its theoretical concept is not undisputed. To further elucidate the electrophysiological characteristics of dental phobia, we investigated visual emotional processing in dental phobia patients and controls. Subjects viewed neutral, phobia-irrelevant and phobia-relevant pictures while magnetoencephalographic and behavioural measures were recorded. All patients reported a history of traumatic experiences and depressive and anxiety symptoms, as well as dissociative and posttraumatic symptoms. In the magnetoencephalography, patients showed generally less evoked neural activation at parietal and temporal regions and a reduced differentiation between picture categories compared to controls. At the behavioural level, patients rated phobia-relevant pictures as clearly more negative as did controls. In contrast to previous reports, our results suggest that dental phobia cannot be associated with the typical effects of biased motivated attention seen in other specific phobias. Instead, results indicate that dental phobia shares typical characteristics with mild forms of posttraumatic stress disorder.

Emotion regulation strategies in trauma-related disorders: pathways linking neurobiology and clinical manifestations

Emotion regulation impairments with traumatic origins have mainly been studied from posttraumatic stress disorder (PTSD) models by studying cases of adult onset and single-incident trauma exposure. The effects of adverse traumatic experiences, however, go beyond the PTSD. Different authors have proposed that PTSD, borderline personality, dissociative, conversive and somatoform disorders constitute a full spectrum of trauma-related conditions. Therefore, a comprehensive review of the neurobiological findings covering this posttraumatic spectrum is needed in order to develop an all-encompassing model for trauma-related disorders with emotion regulation at its center. The present review has sought to link neurobiology findings concerning cortico-limbic function to the field of emotion regulation. In so doing, trauma-related disorders have been placed in a continuum between under- and over-regulation of affect strategies. Under-regulation of affect was predominant in borderline personality disorder, PTSD with re-experiencing symptoms and positive psychoform and somatoform dissociative symptoms. Over-regulation of affect was more prevalent in somatoform disorders and pathologies characterized by negative psychoform and somatoform symptoms. Throughout this continuum, different combinations between under- and over-regulation of affect strategies were also found.

Hypervigilance-avoidance in children with anxiety disorders: magnetoencephalographic evidence

BACKGROUND

An altered pattern of threat processing is deemed critical for the development of anxiety disorders (AD). According to the hypervigilance-avoidance hypothesis, AD patients show hypervigilance to threat cues at early stages of processing but avoid threat cues at later stages of processing. Consistently, adults with AD show enhanced neurophysiological responses to threat in early time windows and reduced responses to threat in late time windows. The presence of such a hypervigilance-avoidance effect and its underlying neural sources remain to be determined in clinically anxious children.

METHODS

Twenty-three children diagnosed with an AD and 23 healthy control children aged 8-14 years saw faces with angry and neutral expressions while whole-head magnetoencephalography (MEG) was recorded. Neural sources were estimated based on L2-Minimum Norm inverse source modeling and analyzed in early, midlatency, and late time windows.

RESULTS

In visual cortical regions, early threat processing was relatively enhanced in patients compared to controls, whereas this relation was inverted in a late interval. Consistent with the idea of affective regulation, the right dorsolateral prefrontal cortex revealed relatively reduced inhibition of early threat processing but revealed enhanced inhibition at a late interval in patients. Both visual-sensory and prefrontal effects were correlated with individual trait anxiety.

CONCLUSIONS

These results support the hypothesis of early sensory hypervigilance followed by later avoidance of threat in anxiety disordered children, presumably modulated by early reduced and later enhanced prefrontal inhibition. This neuronal hypervigilance-avoidance pattern unfolds gradually with increasing trait anxiety, reflecting a progressively biased allocation of attention to threat.

Preliminary Study of Acute Changes in Emotion Processing in Trauma Survivors with PTSD Symptoms

Accumulating evidence suggests traumatic experience can rapidly alter brain activation associated with emotion processing. However, little is known about acute changes in emotion neurocircuits that underlie PTSD symptom development. To examine acute alterations in emotion circuit activation and structure that may be linked to PTSD symptoms, thirty-eight subjects performed a task of appraisal of emotional faces as their brains were functionally and structurally studied with MRI at both two weeks and three months after motor vehicle collision (MVC). As determined by symptoms reported in the PTSD Checklist at three months, sixteen survivors developed probable PTSD, whereas the remaining 22 did not meet criteria for PTSD diagnosis (non-PTSD). The probable PTSD group had greater activation than the non-PTSD group in dorsal and ventral medial prefrontal cortex (dmPFC and vmPFC) while appraising fearful faces within two weeks after MVC and in left insular cortex (IC) three months after MVC. dmPFC activation at two weeks significantly positively correlated with PTSD symptom severity at two weeks (R = 0.462, P = 0.006) and three months (R = 0.418, p = 0.012). Changes over time in dmPFC activation and in PTSD symptom severity were also significantly positively correlated in the probable PTSD group (R = 0.641, P = 0.018). A significant time by group interaction was found for volume changes in left superior frontal gyrus (SFG, F = 6.048, p = 0.019) that partially overlapped dmPFC active region. Between two weeks and three months, left SFG volume decreased in probable PTSD survivors. These findings identify alterations in frontal cortical activity and structure during the early post-trauma period that appear to be associated with development of PTSD symptoms.

Distinct populations of neurons respond to emotional valence and arousal in the human subthalamic nucleus

Both animal studies and studies using deep brain stimulation in humans have demonstrated the involvement of the subthalamic nucleus (STN) in motivational and emotional processes; however, participation of this nucleus in processing human emotion has not been investigated directly at the single-neuron level. We analyzed the relationship between the neuronal firing from intraoperative microrecordings from the STN during affective picture presentation in patients with Parkinson's disease (PD) and the affective ratings of emotional valence and arousal performed subsequently. We observed that 17% of neurons responded to emotional valence and arousal of visual stimuli according to individual ratings. The activity of some neurons was related to emotional valence, whereas different neurons responded to arousal. In addition, 14% of neurons responded to visual stimuli. Our results suggest the existence of neurons involved in processing or transmission of visual and emotional information in the human STN, and provide evidence of separate processing of the affective dimensions of valence and arousal at the level of single neurons as well.

Spatiotemporal dynamics of affective picture processing revealed by intracranial high-gamma modulations

Our comprehension of the neural mechanisms underlying emotional information processing has largely benefited from noninvasive electrophysiological and functional neuroimaging techniques in recent years. However, the spatiotemporal dynamics of the neural events occurring during emotional processing remain imprecise due to the limited combination of spatial and temporal resolution provided by these techniques. This study examines the modulations of high-frequency activity of intracranial electroencephalography recordings associated with affective picture valence, in epileptic patients awaiting neurosurgery. Recordings were obtained from subdural grids and depth electrodes in eight patients while they viewed a series of unpleasant, pleasant and neutral pictures from the International Affective Picture System. Broadband high-gamma (70-150 Hz) power was computed for separate 100-ms time windows and compared according to ratings of emotional valence. Compared to emotionally neutral or pleasant pictures, unpleasant stimuli were associated with an early and long-lasting (≈200-1,000 ms) bilateral increase in high-gamma activity in visual areas of the occipital and temporal lobes, together with a late and transient (≈500-800 ms) decrease found bilaterally in the lateral prefrontal cortex (PFC). Pleasant pictures were associated with increased gamma activity in the occipital cortex, compared to the emotionally neutral stimuli. Consistent with previous studies, our results provide direct evidence of emotion-related modulations in the visual ventral pathway during picture processing. Results in the lateral PFC also shed light on the neural mechanisms underlying its role in negative emotions processing. This study demonstrates the utility of intracranial high-gamma modulations to study emotional process with a high spatiotemporal precision.