Motor-evoked potentials as biomarkers for sexual arousal?

Area of Science:

• Neuroscience
• Psychology
• Human Sexuality

Background:

• Motor cortex excitability is linked to motivational processes.
• Sexual arousal and deceptive behavior can modulate motor cortex excitability.

Purpose of the Study:

• Investigate the influence of lying and sex on motor-evoked potentials (MEPs) in heterosexual individuals.
• Examine how viewing sexually arousing pictures affects cortical excitability during truthful and deceptive responses.

Main Methods:

• 16 heterosexual couples viewed sexual and neutral images.
• Participants answered questions about images truthfully or deceptively in a randomized order.
• Motor-evoked potentials (MEPs) were measured using transcranial magnetic stimulation.

Main Results:

• Lying increased non-normalized MEPs across all picture categories.
• Both sexes showed a descriptive trend of higher MEP amplitudes for preferred sexual stimuli.
• Effect sizes were smaller compared to a preliminary study.

Conclusions:

• Lying increases cortical excitability, but MEPs are not stable markers for deception.
• MEPs' operationalization of sexual motivation is influenced by participant sex, motivation, and lying.
• The experimental design may not be sufficiently valid for diagnosing sexual preference or malingering.