Networks of phobic fear: Functional connectivity shifts in two subtypes of specific phobia

• Published in: Neuroscience letters Vol. 662; pp. 167 - 172
• Main Authors: Stefanescu, Maria R., Endres, Ralph J., Hilbert, Kevin, Wittchen, Hans-Ulrich, Lueken, Ulrike
• Format: Journal Article
• Language: English
• Published: Ireland Elsevier B.V 01.01.2018
• Subjects: Adult; Amygdala; Amygdala - physiopathology; Anterior cingulate cortex; Brain - diagnostic imaging; Brain - physiopathology; Brain Mapping; Cerebral Cortex - physiopathology; Fear - physiology; Fear regulation; Female; Functional connectivity; Gyrus Cinguli - physiopathology; Humans; Insula; Magnetic Resonance Imaging; Male; Neural Pathways - physiopathology; Phobic Disorders - diagnostic imaging; Phobic Disorders - physiopathology; Specific phobia; Young Adult; Functional connectivity; Insula; Specific phobia; Amygdala; Anterior cingulate cortex; Fear regulation
• ISSN: 0304-3940; 1872-7972; 1872-7972
• DOI: 10.1016/j.neulet.2017.10.031

•Phobic fear may be associated with connectivity in emotion-processing circuits.•We found a positive coupling between para-limbic regions in phobia groups only.•The observed negative connectivity in controls might represent fear inhibition.•Stimulus modality may alter functional brain connectivity in dental phobia. Anxiety disorders can be conceptualized by an abnormal interplay of emotion-processing brain circuits; however, knowledge of brain connectivity measures in specific phobia is still limited. To explore functional interactions within selected fear-circuitry structures (anterior cingulate cortex (ACC), amygdala, insula), we re-examined three task-based fMRI studies using a symptom provocation approach (n=94 subjects in total) on two different phobia subtypes (animal subtype as represented by snake phobia (SP) and blood-injection-injury subtype as represented by dental phobia (DP)), and a non-phobic healthy control group (HC). Functional connectivity (FC) analyses detected a negative coupling between the amygdala and the ACC in HC for both classes of phobic stimuli, while SP and DP lacked this inhibitory relationship during visual stimulus presentation. However, a negative FC between the insula and the amygdala was observed in DP during visual symptom provocation, which reversed to a positive FC under auditory symptom provocation pointing to effects depending on stimulus modality in DP. SP showed significantly higher FC towards snake-anxiety eliciting stimuli than HC on an average measure of FC, while DP showed a similar pattern under auditory stimulation only. These findings altogether indicate FC shifts during symptom provocation in specific phobia possibly reflecting impaired emotion regulation processes within fear-circuitry networks. FC hence could represent a prime target for neuroscience-informed augmentation strategies when treating pathological forms of fear.