Gender Differences in Brain Activity during Exposure to Emotional Film Clips: an EEG Study

Abstract

(ProQuest: ... denotes formulae omitted.)Electroencephalogram (EEG) reflects the electrical activity occurring in the brain as a result of neuronal processing and signal flow across the nerve cells, nerve fibres, and synapses. The EEG response of one's brain is known to vary depending on changes in mental states such as different stages of sleep and wakefulness, different emotional states, cognitive performance such as reasoning and decision making, motor and ideomotor (imagined motor) acts like mental rotation. EEG has the advantage over other functional brain imaging tools such as Positron Emission Tomography (PET), functional Magnetic Resonance Imaging (fMRI), functional Near Infra-Red Spectroscopy (fNIRS), that it is non-invasive and that it has superior temporal resolution. Hence, EEG signals as psychophysical markers for monitoring mental states have been gaining importance especially in the domain of social, affective, and cognitive neuroscience. Some evidence already suggests that emotionally arousing films have different impact on male and female audiences. This research intended to investigate whether the nature of such gender difference could be captured in terms of EEG response while viewing film clips depicting various kinds of emotions embedded within familiar social contexts.Gender differences in emotion expression and physiologySex differences in emotion expression, experience and physiology have been studied extensively by many researchers. It has been reported that significant gender difference arises in the expressive component of emotion, with more valance and arousal scores in women compared to men (Ashmore, 1990; Brody & Hall, 1993; Kring & Gordon, 1998). Such differences in emotional expressiveness have been reported to be more pronounced in relation to specific emotion categories: sadness, disgust, fear, surprise, happiness or smiling, and anger (Barr & Kleck, 1995; Kring & Gordon, 1998; Tucker & Riggio, 1988; Wagner, Buck, & Winterbotham, 1993).Some studies have reviewed sex differences in emotional memory encoding and recall (Hamann & Canli, 2004). A PET study by Cahill and colleagues (2001) reported significantly more left sided amygdale activity in female participants during memory encoding, as well as more right sided amygdale activity in male participants during a similar task (Canli, Desmond, Zhao, & Gabrieli, 2002). An fMRI study using event related paradigm reported a greater integration of emotional experience and memory for females compared to males (Canli et al., 2002). Sex differences have also been reported during emotional memory retrieval. In one study, female brains revealed significantly greater activation in the bilateral posterior hippocampus and the cerebellum, and significantly less activity in medial pre-frontal cortex compared to male brains (Bremner et al., 2001). Various EEG studies have reported converging evidence that predominant left frontal EEG activity is associated with the processing of positive affects while viewing film clips containing pleasant scenes, and listening to pleasant music, whereas predominant right frontal EEG activity is consistently linked with the processing of negative affects during exposure to film clips containing unpleasant scenes and listening to unpleasant musical emotions (Jones & Fox, 1992; Schmidt & Trainor, 2001). Wang, Nie, and Lu (2014) reported a movie induction experiment that spontaneously lead subjects to real emotional states and simultaneously have their EEG data recorded. They found that power spectrum feature is a suitable EEG feature for emotion classification. Also, they reported that the trajectory of emotion changes can be visualized by reducing subject-independent features with machine learning algorithms.Using the event-related potential (ERP) paradigm, many researchers reported significant sex difference in processing emotional salience in voice (Schirmer & Kotz, 2003; Schirmer et al. …