Acute Posttrauma Resting-State Functional Connectivity of Periaqueductal Gray Prospectively Predicts Posttraumatic Stress Disorder Symptoms.

BACKGROUND: Posttraumatic stress disorder (PTSD) is characterized by hyperarousal, avoidance, and intrusive/re-experiencing symptoms. The periaqueductal gray (PAG), which generates behavioral responses to physical and psychological stressors, is also implicated in threat processing. Distinct regions of the PAG elicit opposing responses to threatening or stressful stimuli; the ventrolateral PAG evokes passive coping strategies (e.g., analgesia), whereas the dorsolateral PAG (dlPAG) promotes active responses (e.g., fight or flight). We investigated whether altered PAG resting-state functional connectivity (RSFC) prospectively predicted PTSD symptoms. METHODS: A total of 48 trauma-exposed individuals underwent an RSFC scan 2 weeks posttraumatic injury. Self-report measures, including the visual analog scale for pain and the Impact of Event Scale, were collected at 2 weeks and 6 months posttrauma. We analyzed whether acute bilateral PAG RSFC was a marker of risk for total 6-month symptom severity and specific symptom clusters. In an exploratory analysis, we investigated whether dlPAG RSFC predicted PTSD symptoms. RESULTS: After adjusting for physical pain ratings, greater acute posttrauma PAG-frontal pole and PAG-posterior cingulate cortex connectivity was positively associated with 6-month total PTSD symptoms. Weaker dlPAG-superior/inferior parietal lobule connectivity predicted both higher hyperarousal and higher intrusive symptoms, while weaker dlPAG-supramarginal gyrus RSFC was associated with only hyperarousal symptoms. CONCLUSIONS: Altered connectivity of the PAG 2 weeks posttrauma prospectively predicted PTSD symptoms. These findings suggest that aberrant PAG function may serve as a marker of risk for chronic PTSD symptoms, possibly by driving specific symptom clusters, and more broadly that connectivity of specific brain regions may underlie specific symptom profiles.

State rumination enhances elaborative processing of negative material as evidenced by the late positive potential.

Rumination has been shown to increase negative affect and is highly associated with increased duration of depressive episodes. Previous research has shown that enhanced elaborative processing of negative stimuli is often associated with depression and trait rumination. We hypothesized that engaging in rumination would result in sustained elaborative processing of negative information, as measured by late positive potential (LPP) asymmetry, regardless of depression. Participants were experimentally induced to engage in ruminative- or distraction-oriented thoughts and subsequently viewed negative, positive, and neutral images. Our results showed a very specific right-dominant frontal and parietal LPP to negative, but not neutral or positive, pictures in the rumination condition only that was not correlated with any measures of trait rumination or depression symptoms. This suggests that state rumination alone may lead to an enhanced, sustained processing of negative material that is typically associated with depression. (PsycINFO Database Record

BAS Reward Responsiveness: A unique predictor of positive psychological functioning.

Previous research on Reinforcement Sensitivity Theory has well-characterized the Behavioral Inhibition System in terms of its behavioral and emotional manifestations, but the Behavioral Approach System (BAS) is less well-defined, particularly regarding the prominence of reward sensitivity versus impulsivity. Furthermore, few researchers evaluate both systems in one model. We evaluated the relationship between Carver and White's (1994) BIS/BAS Scales and areas of psychological functioning including internalizing, externalizing, affect regulation, and well-being. 497 undergraduates completed a battery of self-report measures. Two structural equation models indicate that the Reward Responsiveness subscale uniquely predicts adaptive functioning across all domains. Reward Responsiveness may be a more pure measure of BAS than other BAS traits and may be important for resilience from maladaptive psychological functioning.

Imbalance of default mode and regulatory networks during externally focused processing in depression.

Attentional control difficulties likely underlie rumination, a core cognitive vulnerability in major depressive disorder (MDD). Abnormalities in the default mode, executive and salience networks are implicated in both rumination and attentional control difficulties in MDD. In the current study, individuals with MDD (n = 16) and healthy controls (n = 16) completed tasks designed to elicit self-focused (ruminative) and externally-focused thinking during fMRI scanning. The MDD group showed greater default mode network connectivity and less executive and salience network connectivity during the external-focus condition. Contrary to our predictions, there were no differences in connectivity between the groups during the self-focus condition. Thus, it appears that when directed to engage in self-referential thinking, both depressed and non-depressed individuals similarly recruit networks supporting this process. In contrast, when instructed to engage in non-self-focused thought, non-depressed individuals show a pattern of network connectivity indicative of minimized self-referential processing, whereas depressed individuals fail to reallocate neural resources in a manner consistent with effective down regulation of self-focused thought. This is consistent with difficulties in regulating self-focused thinking in order to engage in more goal-directed behavior that is seen in individuals with MDD.

Modulation of the startle reflex across time by unpleasant pictures distinguishes dysphoric from non-dysphoric women.

While several investigators have examined differences in affective startle modulation between individuals with and without Major Depressive Disorder, fewer researchers have evaluated the time course of this response, particularly in dysphoric individuals. The purpose of this study was to evaluate emotion modulation of the startle reflex during and after the presentation of affective pictures in dysphoric and non-dysphoric women. Dysphoric subjects showed attenuated startle for unpleasant compared to neutral pictures 1.5s post-stimulus onset relative to non-dysphoric subjects and potentiated startle for unpleasant compared to neutral pictures 3s post-stimulus offset. These findings extend the literature on the time course of affective startle modulation in dysphoria, and mirror results of studies in which other psychophysiological responses were examined in this population with regard to negative emotion.

MAOA T941G polymorphism and the time course of emotional recovery following unpleasant pictures.

Difficulty down-regulating negative affect has been linked with anxiety and depression. In addition, recent studies have identified specific polymorphisms of the MAOA gene related to affective psychopathology. Here we examined whether genetic variation in MAOA was associated with the time course of responses to affective stimuli. Emotion-modulation of the startle blink response was measured during and after affective pictures. Women with the G/G genotype of the MAOA T941G single nucleotide polymorphism showed sustained reactivity to unpleasant stimuli, as evidenced by continued blink potentiation during the picture-offset period. These data suggest that the MAOA T941G polymorphism, which has been previously linked with mood disorders, is associated with a maladaptive pattern of affective responding in women.