Neural Oscillations Supporting Gender Categorization of Faces and Body Silhouettes

Gender categorization of faces and body silhouettes is fundamental to human behavior. However, it remains unclear whether encoding of gender similarity of faces and body silhouettes engages similar or distinct neural mechanisms at different stages of the categorical processing. We addressed this issue by recording magnetoencephalography signals while female participants viewed faces or body silhouettes presented in a repetition suppression (RS) paradigm. We found that early neural RS effects within 200 ms after stimulus onset occurred for female faces in high-beta (22-30 Hz) power in the left inferior frontal cortex (IFC) but for female body silhouettes in alpha band (9-14 Hz) power in the cuneus and in beta band (15-20 Hz) power in the anterior cingulate cortex (ACC). RS of beta band (15-20 Hz) power in the left temporoparietal junction (TPJ) occurred for both female faces and body silhouettes at 200-300 ms. Bidirectional alpha-band transfer between the IFC and TPJ was observed for female faces, whereas unidirectional alpha/beta band transfer from the TPJ to ACC and then to cuneus was evident for female body silhouettes. Our findings suggest a two-stage model of neural encoding of intragender similarity during gender categorization of faces and body silhouettes in women.