Trait anxiety moderates visual pathway contributions to the processing of clear versus ambiguous threat.

[摘要] Introduction: Fear expressions combined with averted gaze clearly signal where threat resides. Fear expressions coupled with direct gaze, however, are more ambiguous. Supporting this contention, Adams and Kleck (2003) found that direct gaze facilitated processing efficiency, accuracy, and perceived intensity of averted versus direct gaze fear expressions. Amygdalar responses have also been found to be greater to clear threat when rapidly presented (300 ms) and to ambiguous threat for more sustained presentations (1 s; Adams et al., 2012). Similar flips in responses have been reported as a function of anxiety (Ewbank et al., 2010). Herein, we focus on differential contributions of the magnocellular (M) and parvocellular (P) pathways, and the moderating role of trait anxiety on neural responses to threat. Methods: Participants (N=108) viewed images of fearful or neutral faces with direct and averted gaze for 1 second presentations while undergoing fMRI. These stimuli were presented in high luminance contrast (Unbiased), low luminance contrast (M-biased), or isoluminant red/green (P-biased) images. Results: M-Clear threat cues yielded relatively greater activation in parietal and prefrontal regions along the dorsal visual stream, whereas M-Ambiguous threat cues evoked little activation. Conversely, P-Ambiguous threat cues yielded relatively greater activation in the occipital and inferior temporal regions along the ventral visual stream and the left amygdala. ROI analyses revealed that M-clear threat cues evoked greater right amygdala activation, whereas P-ambiguous threat cues evoked greater left amygdala activation, with high- versus low trait anxiety subjects showing the greatest increase to both. Conclusion: These findings suggest a differential visual pathway contribution to the perception of clear vs. ambiguous facial threat cues. Critically, these effects were moderated by perceivers' trait anxiety levels, reflecting heightened vigilance to threat, in both the M and P visual streams, to clear- versus ambiguous-threat cues, respectively.

[学科分类] 眼科学