Enhanced contralateral theta oscillations and N170 amplitudes in occipitotemporal scalp regions underlie attentional bias to fearful faces

Abstract

Attending toward fearful faces and other threatening stimuli increase the chance of survival. The dot-probe task is a commonly used measure of spatial attention. Event-related potentials (ERPs) have been found to be a reliable measure of attentional bias. The dot-probe literature suggests that posterior contralateral N170 amplitudes are more enhanced by fearful faces compared to ipsilateral amplitudes. However, ERP methods remove non-phase locked frequencies, which provides additional information about neural activity. Specifically, theta oscillations (5-7 Hz) have been linked to attentional processing. The purpose of this study was to examine the relationship between posterior contralateral theta oscillations and N170 amplitudes in the dot-probe task. A modified dot-probe task was used with fear and neutral facial expressions and EEG data was recorded from 33 electrodes. The ERP and time-frequency data were extracted from the P7 and P8 electrodes (left and right occipitotemporal regions). This study found enhanced N170 amplitude and theta oscillations in the electrodes posterior contralateral to the fearful face. Contralateral N170 amplitudes and theta oscillations were related such that greater N170 amplitudes were associated with greater theta oscillations. The results indicated that increased contralateral N170 and theta oscillations are related to each other and underlie attentional bias to fearful faces.

Keywords: Attentional bias; ERP; Fearful faces; N170; Theta.