Event-Related Alpha Suppression in Response to Facial Motion

Abstract

While biological motion refers to both face and body movements, little is known about the visual perception of facial motion. We therefore examined alpha wave suppression as a reduction in power is thought to reflect visual activity, in addition to attentional reorienting and memory processes. Nineteen neurologically healthy adults were tested on their ability to discriminate between successive facial motion captures. These animations exhibited both rigid and non-rigid facial motion, as well as speech expressions. The structural and surface appearance of these facial animations did not differ, thus participants decisions were based solely on differences in facial movements. Upright, orientation-inverted and luminance-inverted facial stimuli were compared. At occipital and parieto-occipital regions, upright facial motion evoked a transient increase in alpha which was then followed by a significant reduction. This finding is discussed in terms of neural efficiency, gating mechanisms and neural synchronization. Moreover, there was no difference in the amount of alpha suppression evoked by each facial stimulus at occipital regions, suggesting early visual processing remains unaffected by manipulation paradigms. However, upright facial motion evoked greater suppression at parieto-occipital sites, and did so in the shortest latency. Increased activity within this region may reflect higher attentional reorienting to natural facial motion but also involvement of areas associated with the visual control of body effectors.

Neural rhythmic symphony of human walking observation: Upside-down and Uncoordinated condition on cortical theta, alpha, beta and gamma oscillations

“…This was generally related to the desynchronization of mirror neurons activity as studied with EEG and fMRI combination (Arnstein et al, 2011 ), and would reflect a release from inhibition. However, it is interesting to note that our results are in contrast to studies of face perception (Girges et al, 2014 ), which report a greater alpha ERD in response to upright facial motion than in inverted condition. This difference between face and body motion recognition may be explain by high specialization of the brain to face recognition, and in particular to treatment of semantic content of facial gesture (Rojas et al, 2011 ).…”

“…The first alpha ERS is in accordance with recent studies showing similar transient alpha increase in response to upright facial motion (Girges et al, 2014 ). The suppression of the early alpha ERS in Upside-down suggest that the inversion of the body presentation rapidly affect the early visual process.…”

Modulation of Alpha Oscillations in the Human EEG with Facial Preference

“…Recently, Girges et al . reported that an increase in alpha ERD at the parieto-occipital regions reflected activity of the face-specific posterior STS for higher attentional efforts allocated to perceiving upright facial motion [ 32 ]. Consistent with these findings, our results also demonstrated that alpha power for the preferred face group was more decreased than for the non-preferred face group, because the preferred faces required more intensive information processing that was likely to be reflected by alpha ERD.…”

Categorizing identity from facial motion

“…The technique also allowed the authors to separate rigid and nonrigid motion, thus evaluating their contributions to the categorization of identity and gender, respectively. These stimuli have since been successfully implemented in other studies examining the discrimination of individual faces (O'Brien, Spencer, Girges, Johnston, & Hill, 2014;Spencer, O'Brien, Johnston, & Hill, 2006), viewpoint dependence (Watson, Johnston, Hill, & Troje, 2005), and neural correlates of facial motion perception within the visual cortex (Girges, Wright, Spencer, & O'Brien, 2014).…”