Thursday, November 08, 2012

Hard Wired: Bonus Scientific Paper.

David Foster asked if the researchers investigating insula activation in women in the previous post looked at whether or not similar circuitry existed in men. Well, those particular researchers didn't but following paper demonstrated similar neural networks in men.

From, Distinguishing specific sexual and general emotional effects in fMRI—Subcortical and cortical arousal during erotic picture viewing, the authors state;

No differences were found in these effects when comparing females and males. Our findings demonstrate for the first time neural differentiation between emotional and sexual components in the neural network underlying sexual arousal.

Alpha Circuitry.

A while ago I put up a series of posts on the subject of female mate selection based upon my clinical and real life observations. It was my contention that in order for attraction to develop a man must stimulate certain "receptors" in a woman's brain in order to elicit reciprocal attraction. Now a "receptor" was a mental construct of mine meant to have some sort of analogy with a neuro-biological mechanism of the mind. To recap, I posited the existence of an alpha receptor--that is a mechanism which responds to stimuli signifying male sexuality, and beta receptor which responds to friendship and commitment like stimuli. It appears that science now has the data to back me up and analogous neuro-biological "circuity" actually exists in female brains.

From, Correlation of Insula Activation and Self-Reported Quality of Orgasm in Women; the authors, after analysing functional MRI data, conclude:
Neuroimaging data expanded these behavioral results by demonstrating the involvement of a specific left-lateralized insula focus of neural activity correlating with orgasm scores, irrespective of dimension (frequency, ease, satisfaction). In contrast, intensity of being in love was correlated with a network involving the angular gyrus.

These findings strongly suggest that intimate and sexual relationships are sustained by partly different mechanisms, even if they share some emotional-related mechanisms  [Ed]. The critical correlation between self-reports of orgasm quality and activation of the left anterior insula, a part of the partner-related neural network known to play a pivotal role in somatic processes, suggests the importance of somatic information in the integration of sexual experience. On the other hand, the correlation between activation of the angular gyrus and love intensity reinforces the assumption that the representation of love calls for higher order cognitive levels, such as those related to the generation of abstract concepts.
It would appear that when it comes to neural networks there appears a sexual network and a romantic network. But here is the real kicker from the study;

However, no relationship was found between intensity of love and partnered orgasm frequency.

What about the flowers, the roses, the dinners??

Clearly then, if romantic love does not necessarily fuel the sexual fire what does? Another study, however, did find something which modulated women's orgasm frequency. From, Men's masculinity and attractiveness predict their female partners' reported orgasm frequency and timing. The authors conclude:
We found that women reported more frequent and earlier-timed orgasms when mated to masculine and dominant men—those with high scores on a principal component characterized by high objectively-measured facial masculinity, observer-rated facial masculinity, partner-rated masculinity, and partner-rated dominance.
This was an interesting study since it demonstrated that orgasm frequency was contingent upon a male possessing objectively ascertainable characteristics. The relationship quality was an uncorrelated variable.

This fascinating study (abstract only) was able to decouple women's assessment of male facial attractiveness into sexual and non-sexual assessments (two separate circuits):
In the present study, while nonsexual judgments best explained facial attraction in whole-face images, a reversal occurred for split-face images such that sexual judgments best explained facial attraction, but only for mate-relevant faces (i.e., other-sex). These findings indicate that disrupting holistic processing can decouple sexual from nonsexual judgments of facial attraction, thereby establishing the presence of a dual-process.
And this study (abstract only) demonstrated that sexual arousal seems to activated by different set of of neurotransmitters when compared to romantic love:
The sexual arousal responses of women in the Lust group, but not in the Romantic group, were positively and significantly associated with elevated NE and DA. It is feasible that, when women are seeking a partner (Lust), NE and DA may facilitate attention toward sexually relevant stimuli
All in all, the research seems to point towards the existence of two separate neurological circuits. An alpha network; which is concerned with sexual desire, the activation of which is contingent upon men having certain objectively determined characteristics, and and a beta circuit concerned with asexual aspects of male/ female relationships.