Brain areas more activated by fearful than by neutral centrally presented faces in the three analyzed time windows.

<p>For each activation cluster, the Talairach coordinates correspond to the voxel of maximal intensity obtained after the ERB analyses, the volumes are expressed in cm³. The threshold is set at uncorrected p<0.01 (*p<0.005, **p<.001).</p

Brain areas more activated by fearful than by neutral peripherally presented faces in the three analyzed time windows.

<p>For each activation cluster, the Talairach coordinates correspond to the voxel of maximal intensity obtained after the ERB analyses, the volumes are expressed in cm³. The threshold is set at uncorrected p<0.01 (*p<0.005, **p<.001).</p

Sensor responses averaged across subjects and conditions.

<p>Event-related beamformer source analyses were performed in three 50 ms time windows (grey) surrounding the three major peaks. Magnetic activity maps represent the sensor activity for each maximum peak amplitude.</p

Example of trial.

<p>Each trial started with two scrambled faces and a fearful or neutral face presented for 33 ms, centrally or peripherally, immediately masked by 3 neutral faces. After a variable delay the target stimulus was appearing. The subject was asked to press a button when a happy face was occurring.</p

Group source analysis.

<p>The student-t statistic 3D map resulting for the group source analysis are thresholded by the corresponding p-value<0.01. During the first 130 ms, not-consciously perceived peripheral fearful faces enhanced the neuronal activity in the right anterior medial temporal lobe, including parahippocampal gyrus and amygdala.</p

Time courses of activities at the right amygdala site.

<p>The activity elicited at the right amygdale site (21, −4, −15) by peripherally presented stimuli is depicted in black for fearful faces, in grey for neutral faces. The first peak appearing around 115 ms is stronger for fearful faces. The reported pseudo-Z values are taken from the subtraction of time course activities related to fearful faces minus those related to neutral faces in the corresponding voxels.</p

Temporal course representation of stimuli displayed during the phase 3.

<p>The subject of the photograph has given written informed consent, as outlined in the PLOS consent form, to publication of their photograph.</p

Face the Hierarchy: ERP and Oscillatory Brain Responses in Social Rank Processing

<div><p>Recognition of social hierarchy is a key feature that helps us navigate through our complex social environment. Neuroimaging studies have identified brain structures involved in the processing of hierarchical stimuli but the precise temporal dynamics of brain activity associated with such processing remains largely unknown. Here, we used electroencephalography to examine the effect of social hierarchy on neural responses elicited by faces. In contrast to previous studies, the key manipulation was that a hierarchical context was constructed, not by varying facial expressions, but by presenting neutral-expression faces in a game setting. Once the performance-based hierarchy was established, participants were presented with high-rank, middle-rank and low-rank player faces and had to evaluate the rank of each face with respect to their own position. Both event-related potentials and task-related oscillatory activity were investigated. Three main findings emerge from the study. First, the experimental manipulation had no effect on the early N170 component, which may suggest that hierarchy did not modulate the structural encoding of neutral-expression faces. Second, hierarchy significantly modulated the amplitude of the late positive potential (LPP) within a 400–700 ms time-window, with more a prominent LPP occurring when the participants processed the face of the highest-rank player. Third, high-rank faces were associated with the highest reduction of alpha power. Taken together these findings provide novel electrophysiological evidence for enhanced allocation of attentional resource in the presence of high-rank faces. At a broader level, this study brings new insights into the neural processing underlying social categorization.</p></div

Mean (± <i>SE</i>) LPP amplitude (in Microvolts; 400–700 msec) in the for the Highest, Middle and Lowest player as a function of the scalp domain (left, central and right).

<p>Mean (± <i>SE</i>) LPP amplitude (in Microvolts; 400–700 msec) in the for the Highest, Middle and Lowest player as a function of the scalp domain (left, central and right).</p

Mean (± <i>SE</i>) alpha power (in Microvolts²) computed on Pz for the Highest, Middle and Lowest player as a function of the time interval ([100–400 ms] and [400–700 ms]).

<p>Mean (± <i>SE</i>) alpha power (in Microvolts²) computed on Pz for the Highest, Middle and Lowest player as a function of the time interval ([100–400 ms] and [400–700 ms]).</p