Influence of trait anxiety on brain activity during the acquisition and extinction of aversive conditioning.

BACKGROUND: We examined how individual differences in trait anxiety (TA) influence the neural responses associated with the acquisition and extinction of anticipatory anxiety elicited through a context conditioning paradigm, with particular focus on the amygdala and the subgenual anterior cingulate cortex (sgACC).
METHOD: During two sessions of echo-planar functional magnetic resonance imaging (fMRI), 18 healthy volunteers completed a decision-making task with two randomly alternating 28-s to 32-s background screen colour blocks. One of the colours was associated with the presentation of an aversive noise (CTX+) and the other colour was 'safe' (CTX-). In the first session (Acquisition), 33% of CTX+ colour blocks were paired with noise and in the second session (Extinction) no noise was presented.
RESULTS: The amygdala displayed an increased response to CTX+ compared to CTX- colour blocks during the Acquisition and Extinction sessions and the ACC displayed an increased response to CTX+ compared to CTX- colour blocks during Extinction only. In addition, a greater conditioned response (CTX+ minus CTX-) was observed in the ACC when comparing the Extinction and Acquisition sessions. Correlation analyses further showed that higher levels of TA were associated with a higher conditioned response in the amygdala during Extinction as well as a greater differential conditioned response (i.e. Extinction>Acquisition) in the ACC.
CONCLUSIONS: Our results support the idea that individuals with high levels of anxiety-relevant traits and vulnerable to developing an anxiety disorder display a more resilient anxiety response during extinction that is characterized by hyper-responsivity in the amygdala.