How Sexual Desire Works- The Enigmatic Urge

by Frederick Toates

  Concerning Mr P’s sexual wanting (p. 152):

  Sexual and libidinous arousal was still more marked and the transit of any female personnel across Mr P’s field of vision would immediately evoke an indescribably lascivious expression, forced lip-licking and lip-smacking movements…and uncontrollable watching; he seemed – visually – to grab and grasp the object of his gaze, and to be unable to relinquish it till it passed from his field of vision.

  Following the use of L-Dopa, Mr V became hyperactive, amorous and adjusted his spectacles 200–300 times an hour (p. 197). Mr G experienced increased libido with L-Dopa (p. 217).

  The evidence of Mr L points to activation of a general incentive system by the treatment (Sacks, p. 249):

  Mr L passed from a gentle amorousness to an enraged and thwarted erotomania.

  Fantasies were of a hypersexual form. He masturbated for hours each day. At other times extreme hunger and thirst were triggered.

  Parkinson’s disease

  Parkinson’s disease arises from the loss of a particular set of neurons, which employ dopamine.18 A pathway of neurons involved in the control of movement is severely disrupted, whereas the pathway underlying wanting (Figure 2.10) is left relatively intact. Treatments involve trying to boost the activity of dopamine in the neurons of the disrupted pathway but this is non-selective and has the side effect of increasing activity in the relatively intact wanting pathway.

  These treatments sometimes have the unwanted side-effect of triggering addictive-like activities, amongst others gambling, shopping or hypersexuality (Mendez and Shapira, 2011; Politis et al., 2013). Hypersexuality is mainly, if not exclusively, a male phenomenon, whereas binge eating is predominantly female. Sometimes treatments boost the desire for conventional sexual behaviour, as in making excessive demands on a partner or can even trigger sexual desires of a novel form. Again the evidence points to activation of a dopaminergic pathway common to a number of activities. The increased motivation is specific to one or two heightened activities, such as sex or gambling or both together, rather than being a general elevation in wanting (Politis et al., 2013). Therefore heightened dopamine activity appears to lock into interaction with a particular incentive(s) to produce the specific wanting. The incentive might well have been one of importance to the individual prior to the onset of the disorder.

  Consider the case of a 64-year-old retired steelworker in Sheffield, who was treated with the dopamine-boosting substance, L-Dopa (Harvey, 1988, p. 834):

  a young female patient, whom he hardly knew, showed the staff a lurid letter he had sent her in which he made her the object of his fantasised sexual activities…This was most unexpected since his mood was still sombre and at times tearful…he had also started making nocturnal visits to a 12-year-old neighbourhood girl.

  In a study of patients treated with dopamine-boosting drugs in Rochester, Minnesota, a 52-year-old man (Klos et al., 2005, p. 383):

  began buying pornography tapes and admitted to recent extramarital affairs. He denied having any prior interest in pornography. In addition to the pathological hypersexuality, he started gambling, losing hundreds of thousands of dollars, intensified his smoking habit from one to two packs per day, and reported hyperphagia with weight gain of 50lb in 6 months.

  A 54-year-old-man (p. 384):

  propositioned his daughter’s friend for sex in return for money to relieve her financial difficulties. In addition, he requested that his son and daughter-in-law ‘form a threesome’.

  A 59-year-old patient in Los Angeles described (Mendez and Shapira, 2011, p. 1095):

  constantly seeking sexual gratification including going to massage parlours and spending a great deal of money on prostitutes. He began downloading pornography from the Internet, and although not previously known to be sexually interested in children, became especially interested in child pornography.

  Behaviour normalized with the discontinuation of this treatment.

  Those patients most likely to display addictive-like behaviours tend to be characterized by relatively high levels of impulsivity and novelty-seeking (Politis et al., 2013).

  Neuroimaging reveals increased activity in the wanting pathway in medicated patients showing hypersexuality as compared to medicated Parkinson’s patients not showing this (Politis et al., 2013). Increased desire does not appear immediately upon taking the medication but is a gradual process over repeated use, suggesting increasing incentive salience. In response to erotic images (about two-second presentations), patients with hypersexuality showed elevated activity in a number of brain regions,19 including that in which the nucleus accumbens is located, as compared to non-hypersexual Parkinson’s patients. The effect was specific to sexual images and not seen for other incentive presentations such as food. The combination of sexual stimulation and sensitized dopaminergic brain systems is necessary to see the enhanced effect in brain regions linked to desire. Although wanting was increased under these conditions, liking of the images did not increase in parallel. The rated level of sexual desire correlated with activity in the nucleus accumbens and in certain cortical regions.20 From this, the researchers suggested that cortical activity formed the basis of the conscious experience of desire.

  Schizophrenia

  A distinction that corresponds to that between wanting and liking can be applied to people with schizophrenia and might prove relevant to their sexuality. Although they do not necessarily show a reduction in liking things, they typically show a reduction in wanting them. Gard et al. (2007) use the expressions coined by Klein (1987) of ‘anticipatory pleasure’ (the future-orientated pleasure associated with goal-directed activity towards gaining things) and ‘consummatory pleasure’ (the pleasure of engaging with desired things in the here and now). It is the former rather than the latter that is often disrupted. Anhedonia (loss of pleasure) has long been described as a characteristic of schizophrenia, but closer scrutiny suggests the necessity for such a qualification of the description.

  Although there is some inconsistency, most evidence points to a reduction in sexual desire in schizophrenia (Kelly and Conley, 2004). However, there is indirect evidence that sexual pleasure is not decreased to the same degree. Thus, masturbation frequency is often high (Assalian et al., 2000), suggestive of a maintained capacity for pleasure. Occasionally, hypersexuality in the form of a large increase in masturbation frequency or public displays of sexuality is shown (Lukianowicz, 1963; Tracy et al., 1996), along with other behaviours suggestive of a lowering of inhibition. Arieti (1974, 1975) observed a change in the behaviour of patients with schizophrenia over the years. Prior to around 1960, patients rarely showed much expression of sexuality. Some years later, sexual ‘acting-out’, even exhibitionism in the hospital, had become common at the start of a schizophrenic episode.

  It seems that high-level controls underlying anticipation and planning can be compromised (Andreasen, 1987) leaving the lower-level controls intact or even over-sensitive. An increase in a range of behaviours such as sexual behaviour and drinking water is sometimes seen (Luchins et al., 1992), suggesting removal of inhibition on certain activities that are triggered with little effortful cost. Conversely, an abnormally high perceived cost of gaining rewards associated with schizophrenia appears to deter goal-directed action (Gold et al., 2013). Evidence points to abnormalities in the activity of dopamine. There is a loss of sexual desire following treatment of schizophrenia with drugs that block the action of dopamine (Labbate, 2008).

  Depression

  Anhedonia is described as a defining characteristic of depression. Depression is commonly associated with a loss of sexual desire (Baldwin, 2001). There are various aspects of depression, and the distinction between anticipatory pleasure and consummatory pleasure (just described) applies here too (Sherdell et al., 2012). In healthy controls, consummatory pleasure predicts the amount of work people are prepared to perform to gain a desired object. However, in depressed people there is a fracture line; the amount of work performed to gain a rewa
rd, corresponding to anticipatory pleasure, might be low, while consummatory pleasure can be comparable to that of controls.

  There is a small amount of evidence to suggest dissociation between anticipatory and consummatory measures of sexuality in depression. Kennedy et al. (1999) suggest that: ‘depression is more likely to influence the early stages (desire and arousal) of sexual performance’. Klein (1987) described depressed patients who still enjoyed the pleasure of food and sex but made little effort to obtain it. Lukianowicz (1963) found only a slight reduction in masturbation frequency in depression but a drastic reduction in frequency of coitus.

  Link to evolutionary psychology

  The notion of ‘encapsulated modules’, sometimes fails to do justice to insights from a study of the brain. For example, Cosmides and Tooby (1995) argue:

  There is simply no uniform element in sex, eating, drinking, staying warm (but not overheating), and so on, that could be used to build a general architecture[21] that could learn to accomplish these behaviours.

  Contrary to this claim, there appears to be a common system based upon dopamine, which underlies all approach behaviours (Panksepp, 1982). A system of restraint might also be common to any behaviour. This might be a more parsimonious design than for each motivation to have dedicated approach and restraint processes. Cosmides and Tooby (1995, p. 58) argue:

  the ‘sex drive’ is a construct completely inadequate to cope with the structural richness of the factors involved in the differentiated sexual psychologies of males and females.

  Drive is not a construct that is favoured in the present study, in agreement with Cosmides and Tooby. However, their conclusion, that there are totally different processes underlying sexual motivation in men and women, is not favoured here. Rather, it is suggested that there are different weights attached to some common neural processes. There appears to be more weight associated with inhibitory and attachment processes in women. Although there is a difference in the averages, there is nonetheless some overlap between genders concerning desired number of life-time partners and desirability of casual sex (Simpson and Oriña, 2003). The characteristics that men and women regard as desirable in a partner show considerable overlap (Wilson, 1999). Differences between the sexes, rather than simply being the outcome of a genetically determined module, might, at least in part, arise from different developmental trajectories reflecting social norms (Baldwin and Baldwin, 1997).

  Wanting is clearly linked to arousal and the consequences of sexual behaviour, the topic of the next two chapters.

  In summary

  The approach system underlying the experience of sexual desire employs dopamine as a neurochemical.

  The expression ‘incentive salience’ refers to the automatic magnet-like pull of incentives.

  In addition, a goal-directed aspect of desire corresponds to conscious intentions.

  Hormones acting on the brain play a role in sensitizing desire.

  A number of disorders appear to exemplify the role of dopamine in desire.

  Nine Arousal

  As everyone knows, ever since Eve forbidden fruit has always been the most delectable.

  (Casanova, 1798/1958, p. 90)

  Evidence suggests that general arousal triggered by a range of non-sexual events can sometimes spill over into sexual arousal. The chapter will address the issue of the relationship between sexual arousal and sexual desire. The chapter will consider first ‘general arousal’ and then more specifically ‘sexual arousal’.

  Anecdotal evidence on general arousal and its spill-over

  Basic principles

  Some environments are said to be arousing, even some colours are given this description, while other colours are described as relaxing (Apter, 2007). When humans seek to increase arousal, to find excitement, they might go to a busy part of town or engage in a challenging and even dangerous activity. By contrast, to decrease arousal, they might lie on a tranquil beach. Such observations lead to the notion of an optimal level of arousal and humans can try to bring their actual level towards this optimum. People differ in their optimal levels; one person will commonly seek sources of high arousal, while another will try to avoid them.

  Much human behaviour seems to be explicable at least in part as attempts to elevate a level of arousal (Apter, 2007). Methods range from activities such as mountaineering and swimming with sharks, to the socially undesirable, such as making bogus phone calls to the emergency services. Vandalism seems to be motivated by little more than trying to exert action to escape boredom. Other activities appear to have an intrinsic underlying motivation that can get locked into association with arousal. Exemplifying this second type would be a risky business deal or a crime such as bank-robbery. These are motivated in part by a desire to get money but excitement often appears to play an interacting role. A common feature of behaviour that elevates arousal seems to be an element of novelty, unpredictability and often danger, combined with transgression, even illegality.

  There can be both pleasant and unpleasant arousal (Apter, 2007). Pleasant arousal is triggered by a range of desirable situations, including sexual behaviour, whereas unpleasant arousal is characterized as fear and anxiety. Apter observes that the bodily states of pleasant and unpleasant arousal overlap considerably, for example in both conditions heart rate accelerates.

  The writer Graham Greene described his survival of Russian roulette as a young man (Greene, 1971, p. 128):

  My heart knocked in its cage, and life contained an infinite number of possibilities. It was like a young man’s first successful experience of sex – as if among the Ashridge beeches I had passed the test of manhood…At fairly long intervals I found myself craving for the adrenalin drug, and I took the revolver with me when I returned to Oxford.

  Unintended spill-over to sexual arousal

  Ovid reported that witnessing the blood and gore of a gladiatorial combat enhanced the attraction that young men and women felt for each other. Numerous anecdotes suggest that what is forbidden sexually (‘sexual taboos’) can assume heightened attraction (Kronhausen and Kronhausen, 1967). For example, the Victorian writer Walter found it appealing to be intimate with someone of a ‘lower class’. To Walter’s class, it was taboo for a woman to adjust an item of clothing, such as a garter, in public. However, his female companions were prone to do this, which fired Walter sexually. Bertrand Russell, the philosopher, documented that the intensity of sexual passion of one of his affairs was enhanced by the experience of fear in the London blitz (Zillmann, 1984). A law-enforcement officer from Nevada reported (Apter, 2007, p. 120): ‘My problem is that I get no thrill when I’m with a legal prostitute, so I find myself drifting over to the big city across the county line where prostitution is against the law. I realize that this is illegal and probably unsafe, but it seems to be the only way I can get any satisfaction.’

  It appears that, by a revival of memory, fear can still be arousing years after the event. Hatfield and Rapson (1987, p.2 73) observed:

  J.R. a 50-year-old man, reports that when he was 18 and attending an elite Ivy League school, he dated a Smith1 girl. He was sexually inexperienced. She was not. In the car, she began to touch him. He panicked. She said, incredulously: ‘You’ve never had any experience have you?’ Thirty years later, his dreams were still filled with the delicious sexual excitement of this arousing but terrifying experience.

  Transformation of negative emotion into sexual desire can be illustrated by a scenario in which a promising date has been agreed but the individual fails to appear. Forty minutes go by, with rising levels of unpleasant emotion, alternating between anxiety/frustration and anger: ‘Was she serious or just leading me on? Has there been an accident?’ One hour late, the promising date materializes, harassed and full of apologies ‘Terribly sorry. My mobile is not working and I was stuck in traffic.’ My hunch is that the intensity of emotion would not drop suddenly to zero but would maintain its value and be redefined in terms of increased attraction.

  Selecting
an arousing sexual option

  Commonly sexual desire appears to interact with general excitement-seeking. The human brain has the ability to fantasize about future prospects and their anticipated arousal value. The other side of the same coin is the ability to remember past situations of high arousal and compare one’s current arousal level with what it was like back then. Examples of where the seeking of arousal gives amplification to sexual desire are many and span the range of its forms.

  Apter (2007) writes (p. 120): ‘The fact that a sexual act is also a sin can undoubtedly make it wickedly attractive to some people.’ Much sexual interaction, starting with low-level flirting, has the dimensions of high levels of uncertainty and suspense – who knows the outcome? People in established relationships occasionally choose to have sex in places where there is some risk of detection, as on a beach or in a car. Of course, if all that fails, then seeking novel partners would appear to be an effective means of raising arousal.

  Curiosity might be fitted to the notion of aiming to elevate arousal. A number of women in the survey of Meston and Buss (2009, p. 146) reported having sex out of curiosity, ‘to see what sex was like with someone other than their current partners, act out a fantasy’. One reported:

  After I broke up with the first person that I had sex with, I wondered if sex with different people was dramatically different, so I had sex with another boy that I knew and…yeah, it was definitely different.