Zapping desire

I haven't read anything about transcranial magnetic stimulation (TMS) for cognitive improvement for a while.  Oddly, this seems a subject that has never attracted much mainstream media attention, for whatever reason.

But I see in the Journal of Sexual Medicine (thank you Sci Hub), that there is another purpose for which TMS has recently been tried - to see if it can dampen sexual arousal in those who suffer from hypersexuality.  Although this was just a "proof of concept" study, the authors seems encouraged that it did work on dampening sexual arousal.   

The study was pretty basic, though.  And if I read the graphs properly, it wasn't like it killed all arousal after a 15 minute treatment.  But it did seem to have a effect on those who received the real TMS over those who received the sham version.

Interestingly - the study seemed to confirm that stimulation to only the right side had an effect.  The area of the brain is the dorsolateral prefrontal cortex, or DLPFC to its friends:

Meta-analytic neuroimaging findings provide robust evidence for bilateral involvement of the DLPFC in neural processing ofvisual sexual stimuli.10  Our study complements this correlative evidence by showing a causal brain-behavior relationship between the right (but not left) DLPFC and sexual arousal. More specifically, it demonstrates that increasing the activity of the ight DLPFC by high-frequency rTMS leads to a decrease in sexual arousal. Thus, this relationship suggests a specific role of the right DLPFC in regulating, that is, inhibiting, sexual arousal.Moreover, our results affirm previous conclusions, drawn from fMRI, that the right DLPFC is involved in self-regulation of sexual arousal due to its increased activity during attempted inhibition of sexual arousal,  that seems to be specific to the sexual domain.

So, it seems that stimulating the part of the brain that is involved in resisting sex stimulation aids inhibition of arousal.

The paper also mentions that it had been thought that deep brain stimulation of the hypothalamus might work.  But (apart from requiring surgery), it might have an unwanted side effect (my bold):

Based on case reports of stereotaxic interventions in paraphilic patients in the 1970s, the ventromedial hypothalamus was recently hypothesized to represent a promising target for deep brain stimulation.  Although the side effects of deep brain stimulation in general might be lesser than systemic side effects of antiandrogenic drug therapies,it is undeniable that side effects of non-invasive brain stimulation techniques might even be comparatively negligible. Considering not only the involvement in sexual arousal but also its crucial role for encoding sexual preference,33neurostimulation of the hypothalamus might lead to unwanted side effects regarding sexual orientation, for example altered sexual partner preference as observed in male ferrets with lesions of the preoptic area/anterior hypothalamus. In contrast, our non-invasive approach of cortical stimulation may provide a more specific, better tolerated,and safer method that is easy to apply

Well, that's an invitation to Google the topic of "stereotaxic interventions" (I think just means surgical work on lesions) on the hypothalamus and its effect on human sexual behaviour.   From the 2006 paper Neurological Control of Human Sexual Behaviour: Insights from Lesion Studies:

In the 1970s, certain psychosurgical techniques were developed to target sexual behaviour. These were based on experimental work in animals that demonstrated that destruction of the hypothalamic ventromedial nuclei led to the conversion of feline post‐amygdalectomy hypersexuality to hyposexuality.¹³ Roeder and colleagues¹⁴ subsequently developed a stereotaxic method of treating “sexual deviations” in humans. Stereotaxic lesions of the ventral medial hypothalamic nucleus were performed in 10 patients with “sexual deviation” ranging from paedophilic homosexuality to intractable exhibitionism. The results showed that sex drive was diminished or abolished in all cases.¹⁴

Some more specific examples of how brain abnormality has led to problematic sexual behaviour: 

Poeck and Pilleri¹⁵ described a female patient who displayed periodic hypersexual and aggressive behaviour after encephalitis of unknown aetiology. Neuropathological examination revealed extensive lesions to limbic structures, including the hypothalamus, thalamic nuclei and the fornix. Ortego and colleagues¹⁶ described a woman with neuropathologically confirmed multiple sclerosis who developed hypersexuality and multiple paraphilias, including paedophilia, zoophilia and incest over the 2 months prior to her death. She had extensive lesions of limbic structures, including the hypothalamus, basal frontal, septal and temporal regions. Frohman and colleagues¹⁷ described a male patient with altered sexual behaviour characterised by an obsessive and insatiable desire to touch women's breasts. Neuroimaging showed enhancing lesions on the right side of the hypothalamus and mesencephalon.  

The article goes on to give lots of other examples of problems within other parts of the brain that can led to hypersexuality.   

It's all a little disturbing to read such cases, due to the damage they may cause to "faith" in self control and free will.   I would hope it's more an example of "extreme cases making for bad law", so to speak:  you really don't want people who don't have brain lesions to think they can follow impulses because they're just a meat robot with no control.      

On the up side, maybe someone is working on Woody Allen's orgasmatron via TMS?  Ha.  (Actually, the only thing I see about using TMS to increase libido has been about women.)