Disentangling the effects of novelty, valence and trait anxiety in the bed nucleus of the stria terminalis, amygdala and hippocampus with high resolution 7T fMRI

The hippocampus and amygdala exhibit sensitivity to stimulus novelty that is reduced in participants with inhibited temperament, which is related to trait anxiety. Although the bed nucleus of the stria terminalis (BNST)
is highly connected to the amygdala and is implicated in anxiety, whether the BNST responds to novelty remains
unstudied, as well as how trait anxiety may modulate this response. Additionally how novelty, stimulus
negativity and trait anxiety interact to affect activity in these areas is also unclear. To address these questions,
we presented participants with novel and repeated, fearful and neutral faces, while measuring brain activity via
fMRI, and also assessed participants’ self-reported trait anxiety. As the small size of the BNST makes assessing
its activity at typical fMRI resolution difficult, we employed high resolution 7 Tesla scanning. Our results
replicate findings of novelty sensitivity that is independent of valence in the hippocampus. Our results also
provide novel evidence for a BNST novelty response toward neutral, but not fearful faces. We also found that the
novelty response in the hippocampus and BNST was blunted in participants with high trait anxiety.
Additionally, we found left amygdala sensitivity to stimulus negativity that was blunted for high trait anxiety
participants. These findings extend past research on the response to novel stimuli in the hippocampus and
amygdala at high resolution, and are the first to demonstrate trait anxiety modulated novelty sensitivity in the
BNST that is dependent on stimulus valence.