Functional MRI of Sex, when Science is Hot!

Functional MRI (fMRI) enables the researcher to specifically view the areas of the brain activated by a task or an emotion. Many research groups focused on sex (Maravilla et al. Int J Imp Res 2007)! What happens in the brain in a situation of sexual excitement ? Is it the same thing for men and women ? A trip behind the scenes of pleasure…

Different studies have used the projection of erotic images or video in the MRI, with the aim of stimulating sexual excitement. Easier for men… Even if men and women present many similar bilateral areas of activation: anterior cingulate, medial prefrontal, orbitofrontal, insular, and occipitotemporal cortices, amygdala and ventral striatum. Men activate thalamus and hypothalamus as well, proportionately to their excitement (Karama et al. Hum Brain Mapp 2002). The amygdala as well, which is part of the limbic system, seems to be playing a major role in men (Hamann et al. Nat Neurosci 2004).

Studies in positron emission tomography (PET scan), a technique which is older than the functional MRI, have gone further. They imaged some male volunteers while their partners were stimulating them manually until ejaculation and orgasm (Holstege et al. J Neurosc 2003). Activations were additionally seen in the ventral tegmental area, which is also stimulated by the ecstasy associated with heroin use. Maybe the two phenomenon are not so different!

Please note that in a jealous condition, men present activation in areas linked to sexuality and aggression (amygdala and hypothalamus), whereas in women the rear area of the superior temporal sulcus is stimulated (Takahashi et al. Neuroimage 2006). Beware...

Version française: Sexe et cerveau: quand la Science est "hot"!