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.