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Daniel Stjepanovic, Jason Mattingley, Mark Bellgrove; Effects of attentional load and spatial location on amygdala processing of emotional stimuli. Journal of Vision 2011;11(11):602. doi: 10.1167/11.11.602.
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The amygdala is known to play an important role in the processing of emotion-laden visual stimuli (Morris et al., 1996). Recent neuroimaging studies, however, conflict as to whether the amygdala automatically processes emotional stimuli (Vuilleumier et al., 2001) or is subject to capacity limits of attention (Pessoa et al., 2002). If the amygdala is truly automatic then it should be uninfluenced by attentional load. One potential explanation for discrepant findings may be varying spatial location of emotional stimuli across studies, with the amygdala argued to preferentially process stimuli appearing outside the fovea. The present study aimed to directly test the impact of varying levels of attentional load and spatial location on the processing of emotional stimuli in the amygdala.
BOLD signal (3T GR-EPI) in the amygdala was examined in 16 healthy volunteers while they completed a task requiring them to judge the size of gaps recessed into a diamond (Mattingley et al., 2006). Attending to two gaps at a time, subjects indicated which of the two was larger. Attentional load (low vs high) was manipulated by varying the difficulty of the gap judgment task. Faces displaying a neutral or fearful expression were presented at one of three spatial locations: centrally or 8.76° to the left or right of fixation.
A separate behavioral experiment demonstrated the effectiveness of our attentional load manipulation, such that high load resulted in significantly reduced accuracy on a secondary task than did low load, t′(20) = 4.23, p < .05. Preliminary results indicate a significant reduction in amygdala reactivity to fearful faces under conditions of high relative to low attentional load.
Thus, present results confirm earlier findings that the amygdala is sensitive to manipulations of attention. Furthermore, effects of varying spatial location of emotional stimuli on amygdala processing will be discussed.
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