P 41. Motor evoked potentials as biomarker for sexual urge

Abstract

Introduction Previous work documents that motor cortex excitability is modulated by emotional states-induced by music for example. Recently, motivation and reward anticipation-operationalized by the viewing of food or money stimuli and by the use of a slot machine respectively-increased motor evoked potentials (MEPs). Motivational besides emotional, cognitive, and physiological processing is one component of a four component model of sexual arousal. Activity in limbic (emotional) areas is considered to spill over to motor cortex via the basal ganglia (motivation) with top-down control of frontal (cognitive) areas. Objectives Here, we aim to investigate the influence of sexual urge on motor evoked potentials. Materials and methods 24 heterosexual healthy men viewed single stimuli of naked women or men genitals covered with black bars. Control stimuli were generated by Fourier transformation of these stimuli. Each stimulus category was shown 60 times without repetition of one stimulus. Subjects had to judge if they want to see the person naked. Subjects received a transcranial magnetic resonance pulse during the motor preparation phase. Ratings with respect to emotional palatableness, sexual arousal, and sexual motivation were done after the MEP paradigm on a five-point scale. Results Heterosexual men showed increased motor evoked potentials for viewing female in contrast to male sexual stimuli. There were no significant correlations of the ratings with motor evoked potentials. Conclusion Increased motor cortex excitability might be not only related to the attractiveness of the female pictures but also to the aversiveness of the male pictures. Data with respect to homosexual subjects might add further hints for motor cortex excitability as biomarker for sexual urge.