Department of Neurology, Charité-Universitätsmedizin Berlin, Campus Benjamin Franklin, Berlin, Germany.
PLoS One. 2013 Jul 9;8(7):e69107. doi: 10.1371/journal.pone.0069107. Print 2013.
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.
面孔处理依赖于一个专门的神经网络系统，该系统由双侧皮质结构组成，右半球占主导地位。然而，由于早期研究结果的不一致以及最近的研究结果，这种功能偏侧性已经成为一个讨论的话题。特别是，采用行为任务和电生理方法的研究表明，在男性中，只有在面孔感知时，右半球才占主导地位，而女性则表现出对称的双侧面孔处理。本研究的目的是使用全头磁脑图（MEG）进一步研究这种半球处理个人熟悉和异性面孔的性别差异。我们发现男性在枕颞传感器集群中存在右侧化的 M170 成分，而女性则表现出双侧反应。此外，在进行偶极子定位和确定 M170 时间窗中的偶极子强度时，也得到了相同的模式。这些结果表明，男性中与面孔反应相关的神经结构不对称参与，并且可以将这种不对称归因于梭状回。这指定了先前采用事件相关电位（ERP）和 LORETA 重建方法的研究结果，这些结果产生了相当广泛的双侧激活，表现出女性的左侧不对称和男性的右侧偏侧化。我们根据面孔评价过程中的整体面孔处理以及一般视觉策略和对异性面孔的特殊兴趣，讨论了我们在男性中观察到的不对称梭状回激活模式的发现。总之，这里观察到的半球专门化模式为面孔感知中的性别差异提供了新的见解，并提出了关于生物学性别、心理性别以及可能是刺激驱动或任务依赖的相互作用的进一步问题。
