Neurophysiological Basis of Emotional Face Perception and Working Memory Load in a Dual-task MEG Study

Research on the neurophysiological effects of emotional face processing, working memory (WM) load, and their interaction in dual-tasks remains scarce. Therefore, we conducted a combined magnetoencephalography (MEG) and eye-tracking study with 47 participants. The dual-task temporally interleaved a facial emotion discrimination task with a visuo-spatial n-back task. Source-space cluster analyses of event-related magnetic fields (ERFs) and oscillations revealed significant main effects of emotional expression and WM load. During emotion discrimination, enhanced ERFs for negative facial expressions located across the insula, ACC, and face-specific occipital regions suggest amplified emotion processing but also the recruitment of attentional control mechanisms. During the n-back phase, emotional faces did not affect evoked responses when they were task-irrelevant. Interaction trends in pupil dilation indicated that emotion-specific processing is diminished under high WM load. During the n-back phase, increased WM load reduced alpha and low beta oscillations in temporo- and parieto-occipital areas. In addition, reduced target fixations in the presence of negative facial distractors indicated a tendency towards emotion-specific interference. Furthermore, sustained increased WM load affected perceived valence, pupil size, and reaction time in both subtasks. A convergence of neurophysiological, physiological, and behavioral findings points to specific processing modes with greater resource depletion for task-relevant negative expressions and high WM load effects in the dual-task even across phases.

Human Brain Mapping