Although dopamine is often thought of as the reward neurotransmitter, its hormonal nemesis prolactin is actually the one associated with the satisfaction that accompanies sleep, exercise, sex, pregnancy, and breast-feeding. Dopamine seems to be more closely linked to anticipatory desire than to the satisfaction of that desire, hence its role in motivation.
Just as desire and satisfaction seem to mutually exclude one another, dopamine and prolactin mutually inhibit one another in a chemical rivalry. This mutual inhibition sets up the delay period between sexual gratification (prolactin) and the return of sexual arousal (dopamine). Each seeks the other to it’s own demise. Not unlike the continuous variables of position and momentum accuracy in the Heisenberg uncertainty principle, the more available one becomes, the more elusive the other is. They cannot exist simultaneously. Dopamine and prolactin play teeter-totter between desire and contentment.
These neurotransmitter correlates for desire and satisfaction can be tied to our temporal experience. If dopamine is the neurotransmitter associated with our perception of time, then prolactin is the neurotransmitter associated with our experience of timelessness, and the two alternate through mutual inhibition in the way we alternate between desire and satisfaction, time and timelessness.
During satisfaction people experience a release into the timelessness of the present moment as experienced during the prolactin release of breastfeeding and orgasm, characterized by the absence of dopamine. Notably, prolactin also inhibits menstruation in women, hence the continued lack of menstruation while breastfeeding. Menstruation’s synchronization with the moon cycle has been postulated as one of the first markers of time, beyond the day / night cycle, in the evolution of human consciousness. Association between prolactin and timelessness is strengthened by the cessation of the menstrual clock.
Prolactin also stimulates the proliferation of cells that eventually become the axon’s lipid coating, speeding the signal transfer within neurons, greasing the mental gears. These signals are transferred through changing protein conformation within the neuron. These are the same proteins that Penrose and Hameroff postulate participate in quantum superposition, and that I suggest engage timelessness through superposition. Recall that hydrophobicity plays a key role in the preservation of this superposition. Thus the lipid layer that prolactin creates, contributes to the superposition and a sense of timeless satisfaction. The timelessness of satisfaction however is inevitably disturbed by some change that leads to desire and temporality once again.
Frequencies naturally want to fall into alignment with one another achieve the timeless entanglement of entrainment. Asynchrony suggests a precarious instability that will inevitably fall back into the comfort of entrainment. This instability of asynchrony can feel something like dissatisfaction, a desire for the timelessness of entrainment. The grit or discomfort generates the sensation of time, of separation. In this discomfort the brain starts looking for something to latch onto, something to carry it back into resonance. Dopamine, generates this discomfort, and motivates attention to entrain and learn. Dopamine seeks out any slight breeze of novelty and hitches it’s sail to it.
Surprise activates the dopamine system. When something unexpected happens, either good or bad, one’s brain produces dopamine. A flood of dopamine tells the brain, “Pay attention! Something different is happening here and if you want to survive, you better start learning.” This dopamine release increases the rate of cycling around a centralized, looped neural pathway, called the basal ganglia, that connects many parts of the brain. The basal ganglia facilitate connections between different parts of the brain, linking events into meaningful relationships and connecting thought to action.
When teaching a pet or person a new skill, maximum learning is attained through sporadically distributed rewards, rather than every time the new skill is demonstrated. Maintaining the element of surprise keeps the dopamine system engaged, keeping the student engaged. If the rewards are too regularly distributed, they fail to generate the level of desire that unexpected rewards generate. This makes sense because desire stems from not having. If the reward is guaranteed, you basically already have it, so there is no motivation to put forth any extra effort to achieve it. In effect, we crave the motivation of risk and challenge more than the prize, because through that motivation we feel that we are operating at our peak capacity. As we age and/or prosper the element of surprise, risk, and challenge is harder to come by.
Dopamine synthesis and dopamine receptors naturally decrease with age. Once one has been around the block a few times, it all becomes old hat; nothing is surprising anymore, especially if one lives within a fairly standard routine. Whether this is due to or the cause of a decline in dopamine is something of a chicken or the egg question.
When we get rewards that we expect, the dopamine system disengages, but as long as the repetition continues to generate surprise, we continue to seek it out. We seek out surprise in order to eliminate it, yet if it a predictable pattern does not exists, we can become addicted to trying to find it, as in gambling or unrequited love. The rush of dopamine and the sense of aliveness and engagement that it brings feels good, especially for a life ensconced in predictability. This pleasurable activation drives us to try to repeat the surprising event until it becomes predictable, thus facilitating learning, engraining habit, and addiction.
Teenagers’ dopamine baseline is lower than adults’, but and their brains release more dopamine in response to novel events than adults’ do–hence the increased drama of both boredom (low baseline dopamine) and novelty seeking (increased dopamine response). This facilitates teenagers’ excitement about the world and the need to explore and seek out new experiences, maximizing learning while also making them prone to risky decision-making and particularly susceptible to addiction and the throws of romantic love.
The entrancement generated by random rewards engaging the dopamine system is part of the reason that gambling, checking your email, or an unpredictable member of the opposite sex can be so addictive. As psychiatrist Leon Petchkovsky puts it, “Dopamine increases curiosity and meaning-making; curiosity and meaning-making increases dopamine activity. The accompanying affect can be experienced as rapturous, numinous even.” Addiction is a positive feedback loop, where love begets love, drinking begets more drinking, gambling begets more gambling, work begets work, wealth begets wealth, until the system self-destructs.
This is an excerpt from my forthcoming book, “The Texture of Time.”
 Blakeslee, Sandra. 2002. “Hijacking the brain circuits with a nickel slot machine.” In New York Times. Feb 19, 2002. http://www.nytimes.com/2002/02/19/health/19REWA.html?ex=1109134800&en=%202c04664b7eae4b2b&ei=5070 (accessed Sept. 22, 2009)
 Petchkovsky, Leon. 2008. “Some Preliminary Reflections on the Biological Substrate of Meaning-Making.” In The Uses of subjective experience. Proceedings of the Conference ‘The Uses of Subjective Experience: A Weekend of Conversations between ANZSJA Analysts and Academics who Work with Jung’s Ideas, pp. 20-21.
Featured image from:
Gilliam, Alex. 2020. “Build Your Own Seesaw” TinyWPA http://www.tinywpa.org/stories/2020/buildyourown/seesaw