Neurodynamics and connectivity during facial fear perception: The role of threat exposure and signal congruity
Fearful faces convey threat cues whose meaning is contextualized by eye gaze: While averted gaze is congruent with facial fear (both signal avoidance), direct gaze (an approach signal) is incongruent with it. We have previously shown using fMRI that the amygdala is engaged more strongly by fear with averted gaze during brief exposures. However, the amygdala also responds more to fear with direct gaze during longer exposures. Here we examined previously unexplored brain oscillatory responses to characterize the neurodynamics and connectivity during brief (~250ms) and longer (~883ms) exposures of fearful faces with direct or averted eye gaze. We performed two experiments: one replicating the exposure time by gaze direction interaction in fMRI (N=23), and another where we confrmed greater early phase locking to averted-gaze fear (congruent threat signal) with MEG (N=60) in a network of face processing regions, regardless of exposure duration. Phase locking to direct-gaze fear (incongruent threat signal) then increased signifcantly for brief exposures at ~350ms, and at ~700ms for longer exposures. Our results characterize the stages of congruent and incongruent facial threat signal processing and show that stimulus exposure strongly afects the onset and duration of these stages.
Cushing, C., Im, H.Y., Adams, R.B.Jr., Ward, N., Albohn, N.D., Steiner, T.G., & Kveraga, K. (2018). Neurodynamics and connectivity during facial fear perception: The role of threat exposure and signal congruity. Scientific Reports, 8, 2776. [PDF]