Abstract
AbstractThe 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.
Highlights
The human amygdala consciously and nonconsciously processes facial expressions and directs spatial attention to them
The results from this study suggest that when individuals are confronted with salient stimuli that signal potential danger, such as fearful facial expressions, our attentional bias to these stimuli is maintained for a prolonged period of time (i.e. 50 min) and the amygdala remains active during this time
Functional neuroimaging research indicates that the amygdala is reactive to fearful faces when processed at a conscious level (Breiter et al, 1996; Morris et al, 1996), and when conscious awareness has been restricted by backward masking (Liddell et al, 2005; Morris, Öhman, & Dolan, 1998; Whalen et al, 1998; Williams et al, 2005), binocular rivalry (Williams, Morris, McGlone, Abbott, & Mattingley, 2004), and continuous flash suppression (Jiang & He, 2006) as well as in cases of cortical blindness (Morris, DeGelder, Weiskrantz, & Dolan, 2001; Morris, Ohman, & Dolan, 1999)
Summary
The human amygdala consciously and nonconsciously processes facial expressions and directs spatial attention to them. 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. These initial findings indicate that when biologically relevant behavior is sustained, so too is amygdala activation. The results from this study suggest that when individuals are confronted with salient stimuli that signal potential danger, such as fearful facial expressions, our attentional bias to these stimuli is maintained for a prolonged period of time (i.e. 50 min) and the amygdala remains active during this time. Through projections to visual cortex (Adolphs, 2004; Vuilleumier et al, 2004) and the prefrontal cortex (Amaral & Price, 1984; Carlson, Cha, Harmon-Jones, Mujica-Parodi, & Hajcak, 2014; Carlson, Cha, & Mujica-Parodi, 2013) the amygdala mediates the preferential processing of environmental threat
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