1. Characteristics of brain activity in GID people Molo M.T., Vighetti S., Rizzi L., Castelli L., Cantafio P., Cappai E. CE.R.NE - Via della Rocca 24 bis, Turin (Italy) - www.cerne.it - e-mail: mtmolo@attglobal.net INTRODUCTION Nowadays transsexuals still suffer a social discrimination due to their gender identity. A major understanding of the phenomena should help to overcome the prejudices. Our studies investigate the psychophysiological response to emotions, starting from the difference between male and female, scientifically demonstrated. Emotions take an important role in cortical functioning because they are relevant in every activity of our mind. But scientists do not agree about definitions and measures of them: different are the emotions supposed to be fundamental, different are questionnaires used in order to evaluate them. Affective states are usually investigated by heart rate, skin conductance and facial electrophysiological response. But their “origin” seems to be in a subcortical area of the brain called limbic system involving the amygdale, the anterior cingulated and the orbital-frontal cortex. Moreover, some studies support the idea that greater left frontal activity is associated with positive emotions and/or approach motivation, and that greater right frontal activity is associated with negative emotions and/or withdrawal motivation (Harmon-Jones E, 2003). There are no studies in literature dealing with the brain electrophysiological response of transsexuals to emotional stimuli. The aim of the present study is to investigate the brain electrophysiological response to different visual stimuli in transsexuals compared to a control group. METHODS Twenty-four transsexuals (12 male to female- MtF - and 12 female to male - MtF), some of them in hormonal therapy, were enrolled in the study. The control group consisted of 12 heterosexual women and 12 heterosexual men matched for age and educational level. Twenty positive and twenty negative slides were chosen from the International Affective Picture System (IAPS). Each picture was presented for 6 seconds followed by a blank screen for other 6 seconds. Brain electrophysiological activity was measured by Mizar Syrius according to the International 10/20 System DISCUSSION Our study evidences a major activation of the brain alpha and theta rythms in the female compared to the other groups (male, MtF, FtM). The males are less sensitive to visual stimuli with different affective valence (negative and positive). The transsexuals put themselves between the male and the female group and the FtM seem to be more activated than the MtF. So, the transsexuals seem to follow the same “affective trend” of the heterosexuals: their brain activity was similar to the sex they would like to be. This finding supports the idea that transsexuals don’t feel the emotions as we can expect thinking about their gender identity. This is in accordance with the previous studies about the autonomic responses during the slide presentation (Molo M., 2003 ). We agree that affective states aren’t always correlated with gender identity in transsexuals as it happens in some people not suffering from this disorder. REFERENCES Harmon-Jones E. Clarifying the emotive functions of asymmetrical frontal cortical activity. Psychophysiology, 2003:40:838-48. Lang, P.J., Bradley, M.M., Cuthbert,B.N. International affective picture system (IAPS): Instrucion manual and affective ratings. Technical ReportA-4, The Center.For Research in Psychophysiology, University of Florida, 1999. Molo M., Vighetti S., Castelli L., Cappai E., Perozzo P., Neurophysiological correlates to emotional stimuli in transsexuals. XVI° Congresso Mondiale Word Association for Sexology, WAS, Cuba, 10-14 marzo 2003 RESULTS The results were analysed by a statistical package for the brain electrophysiological activity offered by the Mizar Syrius. We considered as within-subject factor the type of slide (positive vs negative) and as between-subjects factor the group (male vs female vs FtM vs MtF ). We considered the alpha rhythm as indicative of attention. We also took into account the theta rhythm as indicative of a subcortical brain activity. The female group was more activated than the male during the negative slides The female group was also more activated than the FtM during both the positive and the negative ones The MtF were more activated than the FtM during the presentation About the alpha rhythm, the results were the following: Female groupMale group About theta rhythm, we found that: The female group was more activated than the male during the positive slides The MtF were more activated than the male during both the positive and the negative slides The MtF were more activated than the FtM during the negative ones MtF groupFtM group Female groupMale group MtF group FtM groupMtF group Positive slide Male groupMtF groupMale group Negative slide Female groupFtM groupFemale group FtM group Positive slideNegative slide We didn’t find any significant difference in the other comparisons between the groups. Moreover, the valence (positive or negative) of the visual stimuli didn’t reproduce the cerebral asymmetrical (left or right) configuration found in other studies.