Sustained, not habituated, activity in the human amygdala: A pilot fMRI dot-probe study of attentional bias to fearful faces

Abstract

The human amygdala consciously and nonconsciously processes facial expressions and directs spatial attention to them. Research has shown that amygdala activity habituates after repeated exposure to emotionally salient stimuli during passive viewing tasks. However, it is unclear to what extent the amygdala habituates during biologically relevant amygdala-mediated behaviors, such as the orienting of attention to environmentally salient social signals. The present study investigated amygdala habituation during a dot-probe task measuring attentional bias to backward masked fearful faces. The results suggest that across the duration of the 50 min (1,098 trial) task both attentional bias behavior and amygdala activity were sustained—rather than habituated. Thus, these initial findings indicate that when biologically relevant behavior is sustained, so too is amygdala activation.

Keywords

• amygdala
• habituation
• backward masking
• attention bias
• fear