Sex and Belonging. Tony Schneider

and dominance have also been linked to having more sexual partners.⁷³ Also people who are sensation-seeking, that is, who tend to pursue thrilling and risky activities (perhaps to compensate for lower levels of dopamine⁷⁴) are more likely to be unfaithful⁷⁵ and to engage in risky sexual behaviours with larger numbers of sexual partners.⁷⁶

      Returning to the question of the genetic contribution to sexual orientation, we find relatively low percentages of such contribution have been found in twin studies. Rosario and Schrimshaw suggest that there is a lack of significant findings in more representative samples of the population when it comes to large familial (sibling versus identical versus non-identical twin) studies. They conclude that up to 50% of homosexual orientation may be attributed to genetic factors ‘of some kind’.⁷⁷ In fact, feminine behaviour in boys, which the intra-uterine hormonal environment contributes to, appears to be a much stronger predictor of male homosexuality.⁷⁸ Either way, there remains a significant proportion of men experiencing same-sex attraction for reasons other than genetic predisposition and feminine inclinations. This is certainly also true of women, where a greater incidence of sexual fluidity is reported. ⁷⁹

Neurochemicals and the sexual response

      The biological mechanisms underlying sexual desire, arousal, and expression involve many different elements. Not least of these is the timely release of various neurochemicals, some of which activate sexual priming and some of which inhibit it. The continually changing composition of these neurochemicals forms an important component of the BDP.

      Let us first consider the neurochemicals associated with sexual arousal. Dopamine and melanocortins are released in the hypothalamus and limbic regions when a person is exposed to various sexual cues, heightening attention and desire: these associate with generating sexual interest. Dopamine is typically associated with expectation of reward, and in its link to encoding expectation of reward, it plays a role in the conditioning process — but also in addiction. This alerts us to the addictive potential of sexual behaviour.⁸⁰ Dopamine release has a role in ‘sexual wanting’. It links with anticipation, excitement, desire, concentration, memory, and learning, as well as enhancing the feeling of meaningfulness in things. It has been linked with sociability, but also to social anxiety.⁸¹ It is not surprising then, that those with a predisposition to high levels of dopamine are more likely to be involved in sexual activity early, and to have many sexual partners.⁸² Dopamine interacts with the hormonal profile. Oestradiol and testosterone can facilitate dopamine activation,⁸³ while dopamine can also stimulate hormone release mediating the body’s fight-and-flight response — which may not be so good for the relationship itself. Critical as dopamine activation is to the sexual reward system, it needs to act in concert with other neurochemical and subjective factors to find expression in any particular sexual impulse.

      The neurochemicals noradrenaline, oxytocin and vasopressin are also associated with sexual arousal. Noradrenaline (or epinephrine) helps regulate sexual arousal and motivation.⁸⁴ Meanwhile, oxytocin and vasopressin are released just before orgasm in both men and women, playing a role in pleasure (motivating future sexual activity), but also in emotional attachment to the person with whom the orgasm is experienced.⁸⁵ This mechanism (along with the role of dopamine) can be understood within the classical conditioning paradigm. Lehmiller (2014) notes that the release of oxytocin plays ‘a vital role in developing bonds between romantic and sexual partners because it is released during physical intimacy’ (p. 99),⁸⁶ while Toates (2014) suggests that the raised oxytocin levels in women following orgasm could ‘consolidate the incentive value of the partner and sense of belonging with this person’ (p. 108). We see here that belonging is not only created by the sense of shared personal space and experience, but is also supported by a biological link between the sexual event and bonding.

      Of course, oxytocin is not only featured in the sexual encounter. It is also released in parent-child bonding which should be anything but sexual. But there is other hormone activity present in the adult sexual profile to distinguish these events — the release of vasopressin and testosterone, for example.⁸⁷ We see here the finely tuned balance of a neuroendocrine system that lays the biological basis for relational experiences; but also the interplay between the bonding qualities of oxytocin and vasopressin, and the territorial and protective aggressiveness with which testosterone release might be associated. Here the source of the bonding experience which associates with belonging is a chemical one. It is easy to see the potential for confusion in regard to the interpretation of one’s experiences of intimacy and belonging; that is, to sexualise a nurturing event, or to feel connected in a sexual event where there is otherwise little emotional connection.

      With regard to the activation of various brain regions, the orbitofrontal cortex, the prefrontal cortex and the anterior cingulate cortex may be involved in the evaluation of sexual attractiveness. Other regions of the prefrontal cortex and the anterior cingulate cortex may play a role in sexual desire through the evaluation of the reward value of external reward stimuli.⁸⁸ Diamond & Dickenson (2012) report that activation of the caudate, insula and putamen brain regions appear to relate both to the experience of sexual desire and romantic love. Pfaus, et al. (2014) note that because of the extensive anatomical and functional connections these neural areas have with many other parts of the brain, ready access is allowed to contextual information to inform both the judgement of sexual attraction and the stimulation of sexual desire. This represents the neural parallel of the many associations made at a subjective and meaning level, and underscores the complexity of the sexual experience.

      However, as the arousal level associated with sexual pleasure is prolonged, neural changes occur in regions of the amygdala and the frontal and prefrontal cortex. This adversely affects capacity for moral affiliations, self-other relations, self-awareness, and interpersonal judgements.⁸⁹ (Perhaps the reverse is also true: that is, that a strong focus on moral affiliations, self-other relations, self-awareness, and interpersonal judgements act to inhibit sexual arousal and sexual pleasure by way of increased activity in these same regions.) Pfaus, et al. (2014) suggest that the function of such neural changes is to help ‘dissolve normal body boundaries, thereby facilitating sexual interactions, which in turn might contribute significantly to the experience of sexual arousal’ (p. 174). We observe here a neural equivalent to the notion of shared subjective space in the experience of sexual activity. During orgasm, reward-related regions of the limbic system and the cerebellum are activated, while the regions associated with vigilance are inhibited.⁹⁰ Simply put, prolonged sexual arousal negatively affects a person’s capacity for objective judgement.

      When it comes to sexual inhibition, other neurochemicals are involved. Some prevent a sexual event occurring in the first place; others bring a sexual event to an end. Opiods, for example, are released in the cortex, limbic system, hypothalamus, and midbrain during orgasm, and mediate sexual reward. In providing the experiential reward found in sexual pleasure and thus serving to sate the drive, its release quickly reduces sexual desire and arousal.⁹¹ Both serotonin (which counters the effect of dopamine) and endogenous cannabinoids are released immediately after a sexual event, shutting down sexual arousal, with serotonin creating a sense of peace and sexual satiety, and endogenous cannabinoids mediating sedation.⁹²

      Not only does sexual inhibition immediately follow orgasm, it can also result from stress or threat.⁹³ However, the latter is subject to individual differences in perception of the degree of threat: a limited amount of stress or threat can have the reverse effect, stimulating arousal for some (especially in those with a high threshold for the capacity to be aroused) but creating inhibition in others. Generally, stress is associated with negative emotions: of guilt, fear, anger, grief, and shame. These emotions result in cortisol release, contributing to inhibition of sexual arousal. In conditions of sexual inhibition, those areas in the forebrain relating to good judgement, alertness, and saliency detection are activated, preventing focus on sexual desire and arousal.⁹⁴ Dual-control theories of sexual arousal such as Perelman’s sexual tipping point dual control model⁹⁵ have been structured around the competing neurochemical activities that determine whether sexual excitation