Neuroscience Letters 424 (2007) 94–99 Gender differences influence brain’s beta oscillatory responses in recognition of facial expressions Bahar G ¨ untekin, Erol Bas ¸ar ∗ Brain Dynamics, Cognition and Complex Systems Research Unit, Istanbul K¨ ult¨ ur University, Faculty of Science and Letters, Istanbul, Turkey Received 27 March 2007; received in revised form 16 July 2007; accepted 20 July 2007 Abstract There are only few studies describing gender differences in recognition of facial expressions. Our study has the aim to analyze the effect of gender differences in oscillatory brain responses. Three sets of Ekman and Friesens’s facial expressions (neutral, angry, and happy) were presented to 26 healthy subjects (13 men) while recording from 13 different scalp locations. Occipital beta response (15–24 Hz) was significantly larger for women than for men during the presentation of face expressions. Our results demonstrate that processing of emotional face expressions clearly differs between men and women. Accordingly, the results indicate the necessity of introducing standardization between male and female subjects by means of oscillatory dynamics. In turn, this standardization may be useful for cognitive and clinical studies. © 2007 Elsevier Ireland Ltd. All rights reserved. Keywords: Gender differences; Event-related oscillations; Beta; Face expressions; Visual perception; Emotion The analysis of brain electrical activity gained considerable importance in the last two decades. The studies cover analy- sis of simple sensory inputs, sensory-cognitive inputs studied by the application of the conventional odd-ball paradigms and various types of working memory paradigms [15,19,21,27,29]. Preliminary work on brain oscillations had started in 1970s; works of Bas ¸ar et al. [6] and of Freeman [14] are among the first ones. Whereas Freeman emphasized the gamma band oscilla- tions as the major physiological network property to understand the brain functions, Bas ¸ar’s group proposed the use of multiple oscillatory activity that are selectively distributed in the whole brain. The present report follows a chain of studies that started first by means of simple stimulation, bimodal stimulation, working memory tasks, and later by presentation of more complex per- cepts “as known and unknown face” [8,9,28]. The analysis of the present results provides a more complex step in comparison to processing of faces. As McCarthy [23] states: in the analysis of electrophysiology of facial percepts, the experimenter is con- fronted with face processing, which comprises (i) perceptual and memory processes required for the recognition of complex stim- ∗ Corresponding author. Tel.: +90 212 498 43 92; fax: +90 212 498 45 46. E-mail address: e.basar@iku.edu.tr (E. Bas ¸ar). ulation as a face, (ii) the identification of the particular face in view, and (iii) the analysis of its facial expression [23]. Recently, we published results on the functional correlates of theta, alpha, and beta oscillations in recognition of faces and differentiation of facial expressions [8,9,17,28] by emphasizing that in process- ing of facial expressions selectively distributed multiple cortical oscillations are involved. We also gained additional evidence for the relevant role of beta oscillatory responses in recognition of faces and facial expressions by integrating the results of previous studies [17,28]. The large-scale networks approach was also used to under- stand the differentiation of facial expressions. Large scale approach means the analysis of electrical events at the whole cortex. Mesulam [24] introduced first the concept of selectively distributed networks in cognitive processing. Earlier results on selectively distributed and coherent multiple oscillatory responses were published by Bas ¸ar [3] in the cat and human brains (for reviews see refs. [4,5]). In the last years, the large- scale hypothesis has became also a keyword with increasing number of publications by von Stein and Sarnthein [32], Varela et al. [31], and Fell et al. [13]. In the vast literature on the differentiated behavior of female and male subjects, it is proposed that in selective attention tasks, female subjects’ processing entails more detailed elaboration of information content than males [25,26]; and female subjects 0304-3940/$ – see front matter © 2007 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.neulet.2007.07.052