By Brooke Napier
Scientists at CalTech simultaneously found a way to stimulate your midbrain without invasive methods (ie: opening up your skull) and make you find them attractive.
Chib, et al. reported in Translational Psychiatry that by using their newly designed noninvasive method called transcranial direct current stimulation (tDCS) on the prefrontal cortex they were able to activate the interconnected midbrain.
Why would you want to activate the midbrain?
The ventral midbrain (also known as: the substantia nigra and ventral tegmental area) is the location of a group of very important dopaminergic neurons (neurons whose primary neurotransmitter is dopamine). These dopaminergic neurons are involved in reward, addiction, movement, cognition, motivation, intense emotions like love, and many more things. TL;DR – they’re important.
The neurons project into multiple areas of the brain and impairments in these neurons have been associated with a number of neurological and neuropsychiatic disorders such as Parkinson’s disease, depression, and addiction.
When impairment occurs the most popular means of influencing these impaired neurons is through pharmacological intervention or deep brain stimulation. Pharmacological intervention will not be region-specific, and will influence the dopamine levels throughout not only the nervous system, but also other systems including the immune system, the pancreas, etc.
And, well, deep brain stimulation is Deep. Brain. Stimulation… wherein neurosurgeons drill a hole into your skull and implant a device that is essentially a brain pacemaker. This device will send electrical impulses to where ever the electrode is placed. Though it sounds medieval, this treatment has been successful in treating symptoms of Parkinson’s disease, depression, dystonia, etc.
Previously (meaning before this study), the only means of non-invasive stimulation of the brain was through methods that could only stimulate neurons on the cortical surface, not anywhere near the ventral midbrain.
One of these methods is called transcranial direct current stimulation, which has been shown to be able to influence midbrain neurons by stimulation of the frontal cortex.
What is transcranial direct current stimulation (tDCS)?
tDCS applys a small current between anodal and cathodal electrodes placed on the scalp, in this case they would be placing the electrodes on the prefrontal cortex in effort to induce activation of dopaminergic neurons in the ventral midbrain.
Is this where the good-looking people come in?
Well, they needed a read-out. Turns out the ventral midbrain is also important in determining attractiveness of other people.
Here’s the set up: The experiment was divided into three sessions. The first session (before stimulation) participants made “facial attractiveness judgements”, during the second session participants were stimulated via tDCS for 15 mins, and during the final session (after stimulation) participants again made facial attractiveness judgments.
There were three experimental groups, the main condition which was the group that received the tDCS treatment (anodal stimulation of the ventromedial prefrontal cortex and cathodal stimulation from the right dorsolateral prefrontal cortex), the sham group that received no stimulation, and the active sham group that received stimulation with the anode and cathode switched.
As the graph depicts, the group that received the tDCS treatment perceived a higher attractiveness level after stimulation. Though the attractiveness level was a great read-out, they also quantified this behavior by measuring activation with functional magnetic resonance imaging (fMRI). fMRI scans show that tDCS treatment induced a larger effect size and that increased with perceived attractiveness levels.
This was the very first time that anyone has shown tDCS directly yields both stimulation-induced changes in the brain connectivity AND corresponding behavioral changes – which makes the future bright for using tDCS in the clinic for treating Parkinson’s disease and psychiatric disorders.
Basically, all of the researchers got a wicked paper and a hot date out of this study.
Chib VS, Yun K, Takahashi H, & Shimojo S (2013). Noninvasive remote activation of the ventral midbrain by transcranial direct current stimulation of prefrontal cortex. Translational psychiatry, 3 PMID: 23756377