Poster F15, Tuesday, March 28, 8:00 – 10:00 am, Pacific Concourse
Does immediate versus diffuse threat evoke dissociable high-resolution functional imaging activation profiles from amygdala and bed-nucleus of the stria terminalis?
Lindsay Knight1, Farah Naaz1, Brooke Siers1, Brendan Depue1; 1University of Louisville
Older models of threat processing have been highly influential, and have suggested differential engagement of the amygdala and the bed nucleus of the stria terminalis (BNST); with immediate threat evoking a phasic response in the amygdala, while diffuse threat leads to a sustained response in the BNST. However, recent work has presented contradictory results, suggesting similar activation profiles for both the amygdala and BNST. To explore whether immediate and diffuse threat are functionally dissociable processes, twenty participants were scanned using high-resolution fMRI (1.5mmX3) while presenting human screams and fearful faces during two different conditions: unpredictable vs. immediate on-set time, as well as differing levels of probability vs. certainty in the diffuse vs. immediate threat conditions, respectively. Results show that the immediate vs. diffuse threat evoked higher activation in bilateral amygdala, specifically in the central nuclei group of the amygdala. Conversely, diffuse vs. immediate threat evoked higher activation in the bilateral BNST. Additionally, the comparison between diffuse vs. immediate threat revealed dorsomedial frontal activations. Secondarily, we conducted ROI analyses for the amygdala and BNST to extract finite impulse response time-series for each region. The time-series for both the amygdala and BNST indicated a relatively quick and short latency response for the immediate threat condition. While conversely, both the amygdala and BNST exhibited a longer to peak and sustained time series for the diffuse threat condition. Our results indicate that the amygdala and BNST show similar, rather than dissociable activation profiles.
Topic Area: EMOTION & SOCIAL: Emotional responding