Motivation and emotion/Book/2017/Orgasm neurology

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Orgasm neurology:
What happens to the brain during orgasm?
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Overview[edit]

It is important to understand what happens in the human brain during orgasm as it is an important aspect of social life, having implications for reproduction, relationships and sexuality (Levin, 2014). While there has been widespread interest in human orgasm in the wider social community, only recently has scientific research begun to explore what occurs in the brain during orgasm. The purpose of this chapter is to answer the question "what happens to the brain during orgasm?". In order to effectively answer this question, research surrounding three main areas will be discussed: brain structures; neurotransmitters and hormones, and non-genital orgasms. By focusing on these three areas, a sufficient understanding of orgasm neurology will be reached.

Questions to be addressed:

  • What is an orgasm?
  • What brain structures are involved?
  •  What else occurs in the brain during an orgasm?
  •  Are there any gender differences?
  • Can an orgasm occur without genital stimulation?

What is an orgasm?[edit]

The word orgasm is derived from the Greek word orgasmos meaning “swollen” or “excited” (Georgiadis, 2011). An orgasm involves physiological, mental and emotional characteristics that are experienced at the peak of sexual excitement through sudden discharge (Georgiadis & Kringelbach, 2012). For males, orgasms result from the stimulation of the penis, while they are the result of clitoris stimulation for females (Georgiadis & Kringelbach, 2012). In both sexes an orgasm includes a loss of control, feelings of release, involuntary muscular contractions, and sharp peaks in cardiovascular arousal (Holstege et al., 2003). Furthermore, an orgasm can be achieved alone through masturbation or with a partner.

Which of the following does an orgasm not involve?

Feelings of love.
Involuntary muscular contractions.
Feelings of release.
Loss of control.


Brain structures[edit]

Figure 1: The lobes of the human brain

Decades of studies examining the brain and its relationship to the human orgasm have demonstrated there are many brain structures involved in and impacted by an orgasm (Georgiadis, 2011). Importantly, these brain structures are involved in the physical, emotional and mental aspects of orgasm. Interestingly, the brain structures involved in sexual responses, meaning arousal, orgasm and resolution, are similar to those structures involved in other pleasurable activities such as eating (Levin, 2014). This suggests just how important sexual activity, especially orgasm, is.

The prefrontal cortex[edit]

The prefrontal cortex (PFC) is an area of the brain located at the front of the frontal lobe and is implicated in an array of functions, including personality development, impulse control, and control and organisation of emotional reactions (Siddiqui, Chatterjee, Kumar, Siddiqui & Goyal, 2008). Areas of the PFC play an important role leading up to and during orgasm for both men and women (Holstege & Huynh, 2011). Leading up to orgasm, when sexual arousal becomes more intense, activity in the PFC decreases rapidly (Georgiadis et al., 2006). Studies have shown that this deactivation of the PFC continues during orgasm (Georgiadis et al., 2006; Holstege & Huynh, 2011
).

One of the major areas that demonstrates this deactivation before and during orgasm is the dorsomedial PFC, which is best known for the role it plays in moral reasoning, social judgement and self-awareness (Forbes & Grafman, 2010; Mitchell, Heatherton, & Macrae, 2002). Georgiadis and colleagues (2006) argue these elements are changed dramatically during sexual activity. Due to this, Georgiadis (2011) argues that deactivation of the PFC decreases moral thinking, judgement, and self-awareness, making an individual more relaxed, stress-free and impulsive. Georgiadis (2011) concludes that deactivation of the PFC plays a role in reaching and completing an orgasm.

The orbitofrontal cortex[edit]

The orbitofrontal cortex (OFC) is an area found in the PFC and is comprised of several distinct regions, each having their own specific functions (Rolls, 2004). Research suggests the OFC plays a major role during orgasm in both men and women (Georgiadis, Reinders, Paans, Renken, & Kortekaas, 2009). Studies have found that during orgasm the OFC shows significant deactivation in various regions, through a decrease in regional cerebral blood flow (rCBF) (e.g. Georgiadis et al., 2006; Georgiadis et al., 2009).

Georgiadis et al., (2009) argues the most prominent region that reliably shows deactivation is the lateral OFC. Georgiadis et al., (2006) argues the decreased activity in the lateral OFC represents sexual disinhibition and a lack of sexual restraint. This is based on research showing that damage to the OFC results in antisocial, impulsive and disinhibited behaviours, such as sexual disinhibition (Yang, Raine, Lencz, Bihrle, LaCasse & Colletti, 2005). Importantly, this could explain why people describe a loss of conscious control while experiencing an orgasm (Mah & Binik, 2001). However, it’s interesting to note that during genital stimulation without orgasm the lateral OFC shows increased activity (Georgiadis et al., 2006). It is believed this represents high inhibition, as individuals are attempting to control and hold off their orgasms.

A second, less researched region that is deactivated during orgasm is the medial OFC (MOFC) (Georgiadis et al., 2009). The MOFC is thought to be a crucial element of the neural network underlying a person’s self-monitoring and self-referential thought (Northoff, Heinzel, Bermpohl, Dobrowolny, Panksepp, 2006). According to Hariri (2000), the deactivation of this network results in a more relaxed state of mind. Therefore the deactivation of the MOFC results in a deactivation of this network, making the orgasm experience a more carefree experience (Georgiadis et al., 2009).

  • Pleasure and Reward Processing --> Georgiadis & Kringelbach, 2012

The cerebellum[edit]

The cerebellum is located in the hindbrain, one of the lowest brain structures, and plays a key role in motor control, balance and some cognitive functions (Wolf, Rapoport & Schweizer, 2009). Increased activation takes place in the cerebellum during an individual’s orgasm (e.g. Georgiadis et al., 2006). The main area this activation is found is the left deep cerebellar nuclei, extending to the anterior lobe of the cerebellum vermis (Georgiadis et al., 2006). Researchers have suggested two main arguments for why this activation occurs.

The first argument concerns the physical movements made during an orgasm. The cerebellum controls muscle tension, which reach peak levels during orgasm (Komisaruk and Whipple, 2005). Komisaruk and Whipple (2005) argue this suggests the cerebellum plays an important role in the muscular movements that occur during orgasm. Additionally, the anterior lobe of the cerebellum vermis is central for the control of the genitalia and axial muscles found in the pelvic floor (Georgiadis et al., 2006; Georgiadis & Kringelbach, 2012). These two areas are strongly implicated in sexual activity and orgasm (Georgiadis & Kringelbach, 2012). Due to this, researchers argue that the activation found in the cerebellum during orgasm is related to motor control (Georgiadis et al., 2006).

The second argument focuses on the emotional aspects involved in an orgasm. In recent research, the cerebellum has been shown to be involved in emotional functions (Turner et al., 2007). As a result of this finding, it is believed that the cerebellum is activated due to the emotional responses that occur during an orgasm (Holstege et al., 2003). However, more research needs to be conducted to determine how and why this occurs.

  • What emotional functions?
  • What specific emotional responses during orgasm?
Figure 2: The nucleus accumbens represented by a red dot

The nucleus accumbens[edit]

The nucleus accumbens (NAc) is located in an area of the brain called the basal forebrain and its most widely known function is its involvement in the reward circuit of the brain (Dafny & Rosenfeld, 2017). This means that when we do something that is considered rewarding, such as eating food, taking drugs, or having sex the NAc is activated (Dafny & Rosenfeld, 2017).

Researchers have found that during orgasm, the NAc is activated for both genders (Georgiadis & Kringelbach, 2012). Bianchi-Demicheli & Ortigue (2007) argues this is due to its involvement in motivation and reward expectation. This expectation results from the “rush” an individual experiences when they orgasm, therefore wanting to experience one again. This is similar to drug addicts and the high they experience as a result of drug use (Dafny & Rosenfeld, 2017). As a result, Bianchi-Demicheli & Ortigue (2007) suggest that future motivation for orgasm is enforced by each orgasm an individual experiences due to the rewarding experiences.

The periaqueductal gray[edit]

The periaqueductal gray (PAG) is the gray matter located in the midbrain, and is involved in a number of neurobiological functions such as pain modulation, anxiety, reproductive behaviour and defensive behaviour (Linnman, Moulton, Barmettle, Becerra, & Borsook, 2012). In a study conducted by Georgiadis et al., (2006) it was found there was stronger activation in the PAG for men compared to women. They argued this could be due to the role the PAG plays in reproductive behaviors specific to the male’s species, such as the reproductive purposes of ejaculation. However, there is insufficient research concerning the PAG, the role it plays in orgasm, and gender differences. Due to this, exploring these elements could provide researchers with a better understanding of the differences in male and female orgasm.

Table 1.

Overview of the Brain Structures involved in Orgasms, their Functions, Activation status and Gender differences

Brain Structure Function Activation Status Gender
The prefrontal cortex Moral thinking

Social judgement

Self awareness

Deactivated Found in both genders
The orbitofrontal cortex Sexual Disinhibition

Self-monitoring & Self-referential thought

Deactivated Found in both genders
The cerebellum Motor control

Emotional processing

Activated Found in both genders
The nucleus accumbens Motivation and reward expectations Activated Found in both genders
The periaqueductal gray Reproductive behaviour Activated Found only in males

Neurotransmitters and hormones[edit]

Figure 2: Dopamin molecule

Brief overview here - what are they, why are they important, in the brain etc.

Dopamine[edit]

Dopamine is a neurotransmitter that is believed to be involved in a number of human mechanisms, including reward-motivation behaviour (Levin, 2014). An abundance of evidence points to dopamine as a key neurotransmitter involved in stimulating human orgasm (Levin, 2014; Kruger, Hartmann & Schedlowski, 2005). According to Levin (2014), a simplistic but effective explanation is that dopaminergic transmission is prosexual, meaning it promotes orgasm. Studies have found that leading up to and during orgasm, dopamine levels increase drastically (Levin, 2014). During ejaculation in men, dopamine-synthesising neurons found in the lower brainstem are significantly activated (Holstege et al., 2003). Further studies have found that dopamine neurons in the nucleus accumbens are activated during orgasm in women (Komisaruk et al., 2004). These two activations result in an increase in the release of dopamine neurotransmitters in the brain. Due to this, these findings suggest that the dopaminergic system plays an important role in the male and female orgasm.

Studies looking at the effect of certain drugs have shown that dopamine has an effect on sexual activity and orgasm. A major finding is that dopamine agonists, which are compounds that activate dopamine receptors, have been shown to facilitate human sexual behaviour and orgasm (Kruger et al., 2005). An example of this is the treatment of Parkinson with apomorphine, which is a receptor agonist (Kruger et al., 2005). The use of apomorphine resulted in hypersexuality, which is understood to be extremely frequent or increased libido (Bowers, Van Woert & Davis, 1971). This drug illustrates the role that dopamine plays in an individuals orgasm. However, it’s important to note that researchers have stated they do not yet fully understand the dopamine mechanisms that are involved in sexual behaviour and orgasm (Levin, 2014).

Serotonin[edit]

Serotonin is a neurotransmitter that is thought to be involved in feelings of well being and happiness in humans (Young, 2007). Research indicates that high levels of serotonin can have an inhibitory effect on arousal and orgasm (Georgiadis, 2011; Levin, 2014). This is most common in individuals who take selective serotonin reuptake inhibitors (SSRIs), which block the uptake of serotonin resulting in increased levels (Levin, 2014).  According to Levin (2014), while all phases of sexual arousal can be impaired, the SSRIs most greatly impact on an individual’s ability to achieve orgasm. Most research in this area has been focused on male erections and ejaculation, and has found that SSRIs greatly impair their ability to produce an erection and ejaculate (Kruger et al., 2005). Unfortunately, little is known about its impact on women or why SSRIs impair orgasm, meaning more research needs to be conducted.

Oxytocin[edit]

Oxytocin (OXT) is a powerful and important hormone involved in the regulation of social interaction and sexual reproduction (Magon & Kalra, 2011). Due to this, it plays a significant role in maternal behaviours such as milk release and infant-mother bonding, empathy, group and partner bonding, and orgasm (Magon & Kalra, 2011).

Figure 3: A mother breast feeding, which is facilitated by oxytocin and results in infant-mother bonding

Research has found that OXT plays a role during orgasm for both men and women (Carmichael et al., 1987; Hurlemann and Scheele, 2016). OXT is believed to play a preparatory role, preparing the penis and vagina for orgasm through muscle contractions and lubrication of the areas (Veening, de Jong, Waldinger, Korte & Olivier, 2015). This conclusion was reached due to the presence of OXT receptors on the male and female genitalia (Gimpl & Fahrenholz, 2001; Veening et al., 2005). Furthermore, studies have found that OXT levels are increased during an individual’s orgasm (Carmichael et al., 1987; Hurlemann and Scheele, 2016). Originally, this was thought to be due solely to the muscular movements involved in an orgasm, such as the movements of the pelvic floor for women (Carmichael et al., 1987). While this has not been disproven, more current research has had a greater focus on the emotional aspect of OXT.

The release of OXT has been linked to feelings of well being, improved social interaction and trust (Churchland & Winkielman, 2012). According to Levin (2014), these changes all take place during an orgasm. Due to this, it has been suggested the release of OXT during orgasm strengthens the emotional tie between partners (Georgiadis & Kringelbach, 2012; Levin 2014). In addition to this, OXT increases during orgasm have been linked to increases in the intensity of the orgasm (Veening et al., 2005). It is not fully understood why this occurs, but Behnia and colleagues (2014) suggests it is related to the perception of the relationship for women and physical performance for men.

Non-genital orgasm[edit]

  • Orgasms can also be reached without genital involvement - sensory (visual), touch (e.g. rectum, nipples,) etc.
    • Why and how?
  • Research suggests that women with complete spinal cord injury can still experience vaginal stimulation and resulting orgasms (e.g. Komisaruk et al., 2004)
  • Komisaruk, et al., (2004) argue that this is due to the role the Vagus role plays in sexual stimulation

Conclusion[edit]

The involvement of numerous brain structures, neurotransmitters and hormones in a human’s orgasm is important. It demonstrates that an orgasm results from the wide spread of neural deactivation and activation, as well as the increase in neurotransmitters and hormones. BLAH!!!

  • Limited current research

See also[edit]

  • Emotion and Sex (Book Chapter, 2010). This discusses the emotional side of sex, and does mention the relationship between orgasms and emotions, which is an interesting relationship that can be seen within the brain.
  • Brain Structures (Wikipedia). To understand the different structures within the brain as this is important to this topic.
  • Orgasm (Wikipedia). To understand what an orgasm is. It also briefly mentions what happens in the brain.
  • Sexual Motivation and Hormones (Book Chapter, 2016). Links to orgasm neurology as it discusses various hormones that are involved in sexual motivation, and more specifically orgasms. The information regarding oxytocin, and the phases of an orgasm are of importance.

References[edit]

Bianchi-Demicheli, F., & Ortigue, S. (2007). Toward an understanding of the cerebral substrates of woman’s orgasm. Neuropsychologia, 45(12), 2645–2659. https://doi.org/10.1016/j.neuropsychologia.2007.04.016

Colson, M.-H. (2010). L’orgasme des femmes, mythes, défis et controverses. Sexologies, 19(1), 39–47. https://doi.org/10.1016/j.sexol.2009.11.003

Forbes, C.E., & Grafman, J. (2010). The role of the human prefrontal cortex in social cognition. Gen Psychiatry, 57(11), 1012—30. doi:10.1001/archpsyc.57.11.1012

Georgiadis, J. R. (2011). Exposing orgasm in the brain: a critical eye. Sexual and Relationship Therapy, 26(4), 342–355. https://doi.org/10.1080/14681994.2011.647904

Georgiadis, J. R., Reinders, A. A. T. S., Paans, A. M. J., Renken, R., & Kortekaas, R. (2009). Men versus women on sexual brain function: Prominent differences during tactile genital stimulation, but not during orgasm. Human Brain Mapping, 30(10), 3089–3101. https://doi.org/10.1002/hbm.20733

Holstege, G., Georgiadis, J. R., Paans, A. M., Meiners, L. C., van der Graaf, F. H., & Reinders, A. S. (2003). Brain activation during human male ejaculation. Journal of Neuroscience, 23(27), 9185–9193.

Komisaruk, B. R., Whipple, B., Crawford, A., Grimes, S., Liu, W.-C., Kalnin, A., & Mosier, K. (2004). Brain activation during vaginocervical self-stimulation and orgasm in women with complete spinal cord injury: fMRI evidence of mediation by the Vagus nerves. Brain Research, 1024(1), 77–88. https://doi.org/10.1016/j.brainres.2004.07.029

Kringelbach, M.L. (2005). The human orbitofrontal cortex: Linking reward to hedonic experience. Neuroscience, 6(9), 691–702.

Levin, R. J. (2014). The pharmacology of the human female orgasm — Its biological and physiological backgrounds. Pharmacology Biochemistry and Behavior, 121, 62–70. https://doi.org/10.1016/j.pbb.2014.02.010

Tiihonen, J., Kuikka, J., Kupila, J., Partanen, K., Vainio, P., Airaksinen, J., Eronen, M., Hallikainen, T., Paanila, J., Kinnunen, I., et al., (1994). Increase in cerebral blood flow of right prefrontal cortex in man during orgasm. Neuroscience Letters, 170(2), 241-243.

External links[edit]