No abstract

Several lines of evidence suggest that the amygdala and the bed nucleus of the stria terminalis (BNST) are differentially involved in phasic and sustained fear. Even though, results from neuroimaging studies support this distinction, a specific effect of a temporal dissociation with phasic responses to onset versus sustained responses during prolonged states of threat anticipation has not been shown yet. To explore this issue, we investigated brain activation during anticipation of threat in 38 healthy participants by means of functional magnetic resonance imaging. Participants were presented different visual cues indicated the temporally unpredictable occurrence of a subsequent aversive or neutral stimulus. During the onset of aversive versus neutral anticipatory cues, results showed a differential phasic activation of amygdala, anterior cingulate cortex (ACC), and ventrolateral prefrontal cortex (PFC). In contrast, activation in the BNST and other brain regions, including insula, dorsolateral PFC, ACC, cuneus, posterior cingulate cortex, and periaqueductal grey was characterized by a sustained response during the threat versus neutral anticipation period. Analyses of functional connectivity showed phasic amygdala response as positively associated with activation, mainly in sensory cortex areas whereas sustained BNST activation was negatively associated with activation in visual cortex and positively correlated with activation in the insula and thalamus. These findings suggest that the amygdala is responsive to the onset of cues signaling the unpredictable occurrence of a potential threat while the BNST in concert with other areas is involved in sustained anxiety. Furthermore, the amygdala and BNST are characterized by distinctive connectivity patterns during threat anticipation.

Feelings of uncontrollability and anxiety regarding possibly harmful events are key features of post-traumatic stress disorder (PTSD) symptomatology. Due to a lack of studies, the neural correlates of anticipatory anxiety in PTSD are still poorly understood. During functional magnetic resonance imaging, female PTSD patients with interpersonal violence trauma and healthy controls (HC) anticipated the temporally unpredictable presentation of aversive (human scream) or neutral sounds. Based on separate analysis models, we investigated phasic and sustained brain activations. PTSD patients reported increased anxiety during anticipation of aversive versus neutral sounds. Furthermore, we found both increased initial, phasic amygdala activation and increased sustained activation of the bed nucleus of the stria terminalis (BNST) during anticipation of aversive versus neutral sounds in PTSD patients in comparison to HC. PTSD patients as compared with HC also showed increased phasic responses in mid-cingulate cortex (MCC), posterior cingulate cortex (PCC), mid-insula and lateral prefrontal cortex (PFC) as well as increased sustained responses in MCC, PCC, anterior insula and lateral and medial PFC. Our results demonstrate a relationship between anticipatory anxiety in PTSD patients and hyperresponsiveness of brain regions that have previously been associated with PTSD symptomatology. Additionally, the dissociation between amygdala and BNST indicates distinct temporal and functional characteristics and suggests that phasic fear and sustained anxiety responses are enhanced during unpredictable anticipation of aversive stimuli in PTSD. Hum Brain Mapp 38:2190-2205, 2017. © 2017 Wiley Periodicals, Inc.

We demonstrate a role for the BNST during unpredictable threat anticipation in PD and provide first evidence for dissociation between phasic amygdala and sustained BNST activation and their functional connectivity. In line with a hypersensitivity to uncertainty in PD, our results suggest time-dependent involvement of brain regions related to fear and anxiety.

Sustained anticipatory anxiety is central to Generalized Anxiety Disorder (GAD). During anticipatory anxiety, phasic threat responding appears to be mediated by the amygdala, while sustained threat responding seems related to the bed nucleus of the stria terminalis (BNST). Although sustained anticipatory anxiety in GAD patients was proposed to be associated with BNST activity alterations, firm evidence is lacking. We aimed to explore temporal characteristics of BNST and amygdala activity during threat anticipation in GAD patients. Nineteen GAD patients and nineteen healthy controls (HC) underwent functional magnetic resonance imaging (fMRI) during a temporally unpredictable threat anticipation paradigm. We defined phasic and a systematic variation of sustained response models for blood oxygen level-dependent responses during threat anticipation, to disentangle temporally dissociable involvement of the BNST and the amygdala. GAD patients relative to HC responded with increased phasic amygdala activity to onset of threat anticipation and with elevated sustained BNST activity that was delayed relative to the onset of threat anticipation. Both the amygdala and the BNST displayed altered responses during threat anticipation in GAD patients, albeit with different time courses. The results for the BNST activation hint towards its role in sustained threat responding, and contribute to a deeper understanding of pathological sustained anticipatory anxiety in GAD.

Interpersonal violence (IPV) is one of the most frequent causes for the development of posttraumatic stress disorder (PTSD) in women. Trauma-related triggers have been proposed to evoke automatic emotional responses in PTSD. The present functional magnetic resonance study investigated the neural basis of trauma-related picture processing in women with IPV-PTSD (n = 18) relative to healthy controls (n = 18) using a newly standardized trauma-related picture set and a non-emotional vigilance task. We aimed to identify brain activation and connectivity evoked by trauma-related pictures, and associations with PTSD symptom severity. We found hyperactivation during trauma-related vs neutral picture processing in both subcortical [basolateral amygdala (BLA), thalamus, brainstem] and cortical [anterior cingulate cortex (ACC), medial prefrontal cortex (mPFC), insula, occipital cortex] regions in IPV-PTSD. In patients, brain activation in amygdala, ACC, insula, occipital cortex and brainstem correlated positively with symptom severity. Furthermore, connectivity analyses revealed hyperconnectivity between BLA and dorsal ACC/mPFC. Results show symptom severity-dependent brain activation and hyperconnectivity in response to trauma-related pictures in brain regions related to fear and visual processing in women suffering from IPV-PTSD. These brain mechanisms appear to be associated with immediate responses to trauma-related triggers presented in a non-emotional context in this PTSD subgroup.

The present findings emphasize the importance of social-context processing in SAD by showing that scrutiny prevents appropriate reward-processing-related signatures in response to positive performances in SAD.

Anticipation of potentially threatening social situations is a key process in social anxiety disorder (SAD). In other anxiety disorders, recent research of neural correlates of anticipation of temporally unpredictable threat suggests a temporally dissociable involvement of amygdala and bed nucleus of the stria terminalis (BNST) with phasic amygdala responses and sustained BNST activation. However, the temporal profile of amygdala and BNST responses during temporal unpredictability of threat has not been investigated in patients suffering from SAD. We used functional magnetic resonance imaging (fMRI) to investigate neural activation in the central nucleus of the amygdala (CeA) and the BNST during anticipation of temporally unpredictable aversive (video camera observation) relative to neutral (no camera observation) events in SAD patients compared to healthy controls (HC). For the analysis of fMRI data, we applied two regressors (phasic/sustained) within the same model to detect temporally dissociable brain responses. The aversive condition induced increased anxiety in patients compared to HC. SAD patients compared to HC showed increased phasic activation in the CeA and the BNST for anticipation of aversive relative to neutral events. SAD patients as well as HC showed sustained activity alterations in the BNST for aversive relative to neutral anticipation. No differential activity during sustained threat anticipation in SAD patients compared to HC was found. Taken together, our study reveals both CeA and BNST involvement during threat anticipation in SAD patients. The present results point towards potentially SAD-specific threat processing marked by elevated phasic but not sustained CeA and BNST responses when compared to HC.