title: 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.
authors.affiliation: Department of Psychology, Brunel University, London, United Kingdom.
authors.forename: Christine
authors.initials: C
authors.lastname: Girges
authors.affiliation: Department of Psychology, Brunel University, London, United Kingdom.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Wright
authors.affiliation: Department of Psychology, Brunel University, London, United Kingdom.
authors.forename: Janine V
authors.initials: JV
authors.lastname: Spencer
authors.affiliation: Department of Psychology, Brunel University, London, United Kingdom.
authors.forename: Justin M D
authors.initials: JM
authors.lastname: O'Brien
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001921:Brain / Q000502:physiology*; D004192:Discrimination, Psychological / Q000502:physiology*; D004569:Electroencephalography; D005071:Evoked Potentials / Q000502:physiology*; D005145:Face; D005260:Female; D006801:Humans; D008297:Male; D009039:Motion Perception / Q000502:physiology*