Sex-Differences of Face Coding: Evidence from Larger Right Hemispheric M170 in Men and Dipole Source Modelling

Abstract

The processing of faces relies on a specialized neural system comprising bilateral cortical structures with a dominance of the right hemisphere. However, due to inconsistencies of earlier findings as well as more recent results such functional lateralization has become a topic of discussion. In particular, studies employing behavioural tasks and electrophysiological methods indicate a dominance of the right hemisphere during face perception only in men whereas women exhibit symmetric and bilateral face processing. The aim of this study was to further investigate such sex differences in hemispheric processing of personally familiar and opposite-sex faces using whole-head magnetoencephalography (MEG). We found a right-lateralized M170-component in occipito-temporal sensor clusters in men as opposed to a bilateral response in women. Furthermore, the same pattern was obtained in performing dipole localization and determining dipole strength in the M170-timewindow. These results suggest asymmetric involvement of face-responsive neural structures in men and allow to ascribe this asymmetry to the fusiform gyrus. This specifies findings from previous investigations employing event-related potentials (ERP) and LORETA reconstruction methods yielding rather extended bilateral activations showing left asymmetry in women and right lateralization in men. We discuss our finding of an asymmetric fusiform activation pattern in men in terms of holistic face processing during face evaluation and sex differences with regard to visual strategies in general and interest for opposite faces in special. Taken together the pattern of hemispheric specialization observed here yields new insights into sex differences in face perception and entails further questions about interactions between biological sex, psychological gender and influences that might be stimulus-driven or task dependent.

Sex differences in social cognition: The case of face processing

“…The left hemispheric involvement of the occipito‐/temporal cortex in women for the processing of human faces has been confirmed in two other independent studies, showing a bilateral pattern of activity of the FFA indexed by N170 ERP response in females, as opposed to the typical male right‐side hemispheric asymmetry (Proverbio et al, , ). A similar pattern of results has been shown by Tiedt et al (). Interhemispheric transfer time of face‐related inputs seems also to be asymmetric across sexes: N170 recorded in men have faster latencies in the left visual field (LVF)/RH→LH (170 msec) direction than in the right visual field (RVF)/LH→RH (185 msec) direction, whereas it is symmetrical in women (Proverbio et al, ).…”

Event-related potentials modulated by the perception of sexual dimorphism: The influence of attractiveness and sex of faces

“…The results from this later study are difficult to interpret as the sex of participants was not described, especially taking into account the evidence that women and men respond differently to different sex faces (e.g. Godard & Fiori, 2010;Tiedt, Weber, Pauls, Beier, & Lueschow, 2013).…”

Face processing in the brains of pre-school aged children measured with MEG

“…Some studies reported a strongly right-biased N170 (Eimer and McCarthy, 1999;Goffaux et al, 2003;Sagiv and Bentin, 2001;Taylor et al, 2001) while others did not find this effect (Bötzel et al, 1995;Eimer, 2000;Rossion et al, 2000). There is also evidence for substantial gender differences in the extent of N170/M170 lateralization (Proverbio et al, 2010;Tiedt et al, 2013).…”