Visual Angles and Emotional Valence Affect Temporal Dynamics of Neural Representations of Facial Expression: An MEG Study

Emotion processing has been a focus of research in Cognitive Neuroscience for decades. While the evoked neural markers as brain activations in response to different emotions have been reported, the temporal dynamics of emotion processing have received little attention. Furthermore, behavioral studies have found that the right side of the human face expresses emotions more accurately than the left side. Therefore, accounting for both the content of the emotion and the visual angle of the presentation from the viewer's perspective, we have investigated temporal dynamics and variability in the processing of happy and sad emotions using magnetoencephalography (MEG), when the visual angle of presentation was either Positive (right side of the face) or Negative (left side of the face). Our results showed that decodable processing of happy emotions emerged earlier than that for sad emotions, irrespective of visual angle. However, the amplitude of the evoked response to sad emotions was higher than that to happy emotions, when faces were presented at Positive visual angles only. Source reconstructed Event Related Fields (ERFs) showed localized activities in ventral and dorsal streams including fusiform gyrus, lingual gyrus, putamen and pre and post central gyrus. Multivariate pattern analysis also demonstrated successful decoding of happy and sad emotions only when the facial expression was viewed from a positive visual angle.