Neural Representation of Subjective Sexual Arousal in Men and Women M. Parada 1, M. Gérard 1, K. Larcher 2, A. Dagher 2, Y. M. Binik 1 1. Mcgill University, Department of Psychology 2. Montreal Neurological Institute & Hospital, Department of Neurology & Neurosurgery
Sexual Arousal • Emotional/motivational state that can be inferred from central, peripheral, or behavioural responses triggered by internal & external stimuli • Inferred by peripheral psychophysiological indices or subjective verbal & non-verbal responses • Sexual concordance has given rise to large literature on sex differences in arousal patterns and potential methodological artifacts • Essential elements of subjective sexual arousal? “awareness of genital change” … “feelings of mental excitement”
Neuroimaging of Sexual Arousal • Activation Occipitotemporal cortex Orbitofrontal cortex Anterior cingulate cortex Superior & Inferior parietal lobules Caudate nucleus Left ventral premotor cortex Putamen Insula Claustrum Hypothalamus • Deactivation Lateral temporal cortex • Neural components of sexual arousal: emotional, motivational, attentional, motor processes
• 9 f. MRI & 3 PET neuroimaging studies, included female data • Men = Women or Men = Women • Many inconsistencies in methodology • Induce arousal passively, no active task to assess the individual components of sexual arousal
Neuroimaging of Subjective Sexual Arousal (SSA) How aroused were you? 1 -2 -3– 4 -5
Aims • Investigate where subjective sexual arousal is represented in the brain • Linear relationship between SSA and brain activity? • Assess gender difference
Method • Functional magnetic resonance imaging (f. MRI) • Blood oxygenation level dependant (BOLD) signal • Continuous measure of subjective sexual arousal (SSA) • Presentation of long visual sexual stimuli (erotic & humour) • Men and women
Participants • 20 men, 20 women (age range 18 - 31) • Heterosexual, easily aroused to visual sexual stimuli • Prior sexual experience (sexual intercourse) • Women: regular menstrual cycle • Right handed • Exclusion: Problems with sexual arousal, dysfunction (FSFI, IIEF), STIs, substance abuse, major psychiatric problems, medications affecting arousal, neurological conditions, fear of enclosed spaces, pregnancy • Women were tested during the follicular phase of their menstrual cycle.
Procedure
0 not at all 10 most ever
Main Outcome Measures • Continuous ratings of subjective sexual arousal (SSA) • 10 -point Likert-like scale • 0=not at all aroused…. 10=most aroused ever • Discrete ratings of liking and wanting • 10 -point Likert-like scale • 0=not at all …. . 10=most ever • Brain activity represented by BOLD • 3 Tesla Seimens Magnetom Trio Tim, • 3 D-high resolution structural scan • T 2 -weighted echo-planar (EPI) gradient echo sequence, TR 2600 ms
Statistical Analyses • Subjective sexual arousal, liking and wanting • 3, Mixed three-way ANOVAs on mean ratings • within-subjects factors (trial, stimulus type) • between-subjects factor (Sex) • BOLD signal • General linear modelling (GLM) using FMIRB Software Library (FSL) • Parametric modulation of subjective ratings • Low, Med, High ratings as individual regressors in the model • Cluster thresholding set to p<0. 05, corrected for multiple comparisons • Contrasts for positive linear trends [-1, 0, 1] and [1, 0, -1] • Contrasts between men and women [women>men], [men, women]
Findings SSA ratings significantly increased during erotic videos for men and women
Erotic videos induced more wanting of sexual stimulation than humour videos Liking scores were similar for stimulus type, across trials, and between men and women
Clusters of activation corresponding to linear increase in SSA Superior parietal lobule Postcentral gyrus Supramarginal gyrus Parietal operculum
• Parietal Lobe • Processing center for spatial attention, sensorimotor integration and higher order cognitive functions • Post central gyrus = Primary somatosensory cortex and Parietal operculum = secondary somatosensory cortex, main sensory receptive area for sense of touch, temp, pressure relayed from the thalamus • Monitoring of bodily states, self-awareness, and cognition and attention to sexual stimuli Supramarginal Gyrus Postcentral Gyrus Parietal Operculum Superior Parietal Lobule • Subjective self-assessment of sexual arousal engages these regions into action, combining multiple processes into the subjective experience
Subjective Brain Genitals
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