UNIVERSITA DEGLI STUDI DI TORINO A S O

UNIVERSITA’ DEGLI STUDI DI TORINO A. S. O. S. Giovanni Battista – Molinette - Torino Divisione Universitaria di Urologia II Direttore Prof. D. Fontana FONDAZIONE CARLO MOLO ONLIS NEUROPHYSIOLOGICAL POSTOPERATIVE VARIATIONS IN Mto. F TRANSSEXUALS M. Molo, L. Rolle, S. Vighetti, P Perozzo, M. Timpano, M. Falcone, L. Castelli, D. Fontana

Aim of the study… To investigate neurophysiological patterns, particularly the P 300 wave, and to compare data collected before and after Sex Reassignement Surgery

INTRODUCTION Animal studies have demonstrated the existence of sexual dimorphic brain areas related to sexual behaviour Arnold 1976, Mac Lusky 1981 Dimorphic cerebral areas exist in humans Hofman 1989, Allen 1990

Dimorphic areas have specific cellular patterns in terms of: • Numbers of neurons (Kruijver 2000) • Type of neurons (Cooke 1999)

ü Men and women differ in processing cognitive and emotional information ü Emotions are characterised by: • valence (positive or negative) • arousal ( high or low) Women have greater answers to negative emotional stimuli when compared with men

Interstitial nucleus of anterior hypotalamus Basal nucleus of stria terminalis Preoptic area nucleus Locus ceruleus Amygdala

Materials and methods ü 15 Mt. F transsexuals ü 60 slides from the IAPS: 20 positive, 20 negative and 20 neutral ü Recording of the P 300 evoked activity in Cz, Fz and Pz electrodes ü Statistical analysis: t. test for pair samples

P 300 - ERP • P 300 ERP is a positive deflection located 300 ms after the presentation of a stimulus • To be elicited the subject must concentrate on the visual stimulus • P 300 amplitude is correlated to the subject’s attention

P 300 - ERP • The visual related P 300 is known to represent updating mechanism of task-relevant information and is influenced by the emotional characteristics of pictures Armehein 2004 • Gender differences in the amplitude of the visual ERP have been reported in literature, reporting a major P 300 amplitude in women than in men Geisler 1990, Deldin 1994

P 300 – Parameters • Latence considers the time between the elicitation of the stimulus and the deflection on the EEG • Topography position on the cranic surface where is recorded the maximum amplitude of the electrode • Amplitude the amount of the deflection, starting from the basal status

Results Positive stimuli Pre vs post p<0, 01

Positive stimuli Pre vs post p<0, 01 Positive stimuli Mto. F pre Mto. F post Latence Amplitude Area Pz 342, 4 4, 7 95, 7 Pz 361, 4 6, 73 104, 4 p<0. 01 Cz 342, 4 2, 9 89, 7 Cz 363, 9 4, 1 99, 8 p<0. 01 Fz 340, 6 1, 8 71, 1 Fz 359, 3 2, 7 84, 9 p<0. 01

Results Negative stimuli Pre vs post p<0, 01

Negative stimuli Pre vs post p<0, 01 Mto. F pre Mto. F post Latence Amplitude Area Pz 349, 8 3, 0 117, 9 Pz 371, 7 5, 3 128, 5 p<0, 01 Cz 351, 2 3, 4 119, 0 Cz 386, 5 6, 2 133, 3 p<0. 01 Fz 354, 9 2, 9 91, 2 Fz 376, 5 5, 2 107, 6 p<0. 01

Results Neutral stimuli Pre vs post p>0, 05

Neutral stimuli Pre vs post p>0, 05 Mto. F pre Mto. F post Latence Amplitude Area Pz 309, 0 2, 8 107, 7 Pz 307, 73 2, 5 109, 4 p>0, 05 Cz 305, 0 1, 9 96, 43 Cz 304, 9 2, 4 95, 9 p>0, 05 Fz 307, 4 1, 4 63, 5 Fz 306, 6 1, 3 62, 6 p>0, 05

Results • Results evidenced a statistically significant post-surgery increase (pre vs. post-surgery period) in P 300 values for the negative and the positive slides, while no difference was found for the neutral slides • P 300 values were higher in latency, area and amplitude for positive or negative valence pictures in post-SRS recording. • These differences were higher under the Cz electrode

Results P 300 AMPLITUDE (Cz electrode) 7 6 5 4 Pre-surgery After-Surgery 3 2 1 0 Positive Negative Neutral

Discussion ü In post SRS recording P 300 values were higher in latency, area and amplitude for slides of positive and negative valence ü P 300 feautures in post-SRS recording were even more similiar to women controls our results seem to confirm that Mt. F transsexuals show a neurophysiological pattern similar to subjects of the sex they would like to be ü This results seem to confirm that SRS have a feminizing effect on the brain of Mt. F transexuals