Control of the anterior cingulate/mPFC over the amygdala: a longitudinal fMRI study in patients with panic disorder

Neurobiologically, panic attacks in humans hold similarities to what in animals can be elicited by fear conditioning: A fear network, centred in the amygdala and involving interactions with the medial prefrontal cortex (mPFC) is assumed to mediate emotional, endocrine, motor and autonomous reactions during acute fear. This study focusses on the hypothesis that an altered mPFC/amygdalar interaction represents a neural substrate of panic disorder (PD). We probe this by applying an emotional conflict paradigm during fMRI to 20 patients diagnosed with PD. Congruent and incongruent image/word pairs are presented as mixed even-related/block design. Analysis involves dissociating a conflict monitoring phase from a resolution phase by accounting for the order of the individual trials. The design allows for analysing general deactivation of default mode activity during cognitive demanding task, conflict resolution versus monitoring, and mPFC/amygdala interactions. Drug-naïve patients are followed up after initiation of citalopram medication. 20 control subjects are scanned repeatedly to control for habituation. So far, controls (N=10) but not PD patients (N=10) showed faster reaction times in high versus low conflict resolution trials. Second level random effect fMRI analysis revealed more activation in the rostral ACC/mPFC during high conflict resolution trials in controls than PD patients (p<0.05). Dynamic causal modelling is applied to investigate the mPFC/amygdala interpla