When was the first time you learned about dopamine?
For me, the first time I heard about it was in a song titled “Dopamine” by the rapper Bas,
In the song, Bas explores themes of happiness, fulfillment, and addiction in a self-introspective way.
The next few times I heard about dopamine, it was during neuroscience and medical school courses. Parkinson’s disease, movement disorders, addiction and reward, learning, you name it..it seemed like everything had something to do with Dopamine. More recently though, I have been revisiting the neuroscience of addiction to better understand what happens to us in these intense craving states and guess what came up again? Dopamine.
This post will be a combination of all that I have learned so far and some additional research on dopamine’s effects on our brains and bodies. From a wellness radicalism perspective (previous essay), it is crucial for anyone interested in living well to learn about this because understanding your brain better is the first step to better focus and decision-making. Downstream of this work lies a more meaningful and sustainable approach to wellness, i.e: to start tackling the problem of inner alignment.
Introduction
Dopamine is a neurotransmitter that is produced and released by many types of nerve cells in the brain and body. It operates at synapses and in downstream post-synapse signalling, affecting our ability to move, feel, be motivated, learn and so much more. It was initially discovered in the late 1950s by two independent research groups: Arvid Carlsson's group at the University of Lund in Sweden, and Julius Axelrod's group at the National Institutes of Health (NIH) in the United States.
Carlsson's group was studying the role of neurotransmitters in the brain and discovered that dopamine was present in the brain and was involved in the regulation of movement. They also astutely found that dopamine levels were reduced in the brains of patients with Parkinson's disease, which suggested that dopamine might be involved in the control of movement.
Axelrod's group was studying the biochemistry of nerve transmission and discovered that dopamine was present in the brain and was involved in the regulation of emotion and behavior. They also found that dopamine was involved in the effects of drugs of abuse, such as amphetamines (stimulants), which led to the hypothesis that dopamine might be involved in addiction and that these drugs operate by increasing the amount of dopamine available to certain brain pathways.
Both groups published their findings in the late 1950s, and their work laid the foundation for the modern science of dopamine and its role in the brain, including the pivotal idea that dopamine is involved in addiction and that most (if not all) addicitive drugs operate by temporarily increasing the amount of dopamine available to certain brain pathways.
There are four main dopaminergic pathways in the brain, these are as follows,
The mesolimbic pathway: a dopaminergic pathway that begins in the ventral tegmental area (VTA) and extends to the nucleus accumbens. This pathway is involved in reward and pleasure, and is also involved in the reinforcing effects of drugs of abuse. The nucleus accumbens plays a significant role in our ability to perceive pain/pleasure.
The mesocortical pathway: begins in the VTA and extends to the prefrontal cortex. This pathway is involved in the regulation of cognitive processes, such as attention, memory, and decision-making. Note that Psychosis can arise from dopamine overstimulation in the mesocortical pathway which is why antipsychotics are often primarily anti-dopaminergic drugs.
The nigrostriatal pathway: this pathway begins in the substantia nigra and extends to the basal ganglia. This pathway is involved in the control of voluntary movement and coordination. This is what goes awry in Parkinson’s disease.
The tuberoinfundibular pathway: this begins in the hypothalamus and extends to the pituitary gland. This pathway is involved in the regulation of prolactin release (lactation). Yes, dopamine is involved in this too.
I. Dopamine and Reward-based learning
As a neurotransmitter in the mesolimbic pathway, dopamine plays a significant role in the brain's pleasure and reward system, which is responsible for reinforcing behaviors that are beneficial for survival by making them enjoyable (via nucleus accumbens).
In the current models of reward-based learning, whenever animals engage in activities that are rewarding (e.g eating chocolate, cocaine), small amounts of dopamine are released in their brain in specific patterns and pathways. This uptick reinforces that behavior, often in a dose-dependent way, and thus makes the agent more likely to repeat this action in the future. By coordinating all the synergistic roles of dopamine within the brain, we have a 100% success rate when it comes to repeating actions that increase dopamine in the future. This is not an opinion, it is a fact of evolution.
Increased dopamine was a pure evolutionary fitness signal in the wild so we used it to simplify our learning. Anytime it went up in an agent’s brain. it would usually mean that the organism has found external success (fresh kill= nutritious food, sex= reproduction, etc). The problem is that we have hacked directly into this feedback loop, inserting VR porn, 4k tik-toks, engineered food etc into the mix so now our brains constantly think we are the evolutionary “epitome” of the species.
Why would the epitome of the species need any extra motivation to do homework or other forms of delayed gratification that our ancestors took part in?
Our mesolimbic feedback mechanisms are saturated with manufactured noise and it makes us evolutionary misfits.
III. Dopamine and Incentive-salience in addiction
Another facet of the biology of Dopamine that I wanted to discuss is incentive salience. This is defined as the process by which the brain assigns value to a particular stimulus, such as a food or a drug, based on its ability to produce pleasure or reward. As we saw earlier, this is how things that increase dopamine become relevant/salient to our lives and behavior. The incentive value of any action can be mapped out based on its expected reward. Any unexpected changes to our predicitions in the direction of less dopamine (e.g. power goes off while playing a game) is interpreted as pain in the system whereas getting more dopamine than expected (e.g. stranger gives you 100$) can create an intense sense of pleasure.
This process is thought to be a key factor in addiction, as it can lead to the development of strong cravings for a particular substance or behavior that has a high predicted dopamine pay-off. Many drugs of abuse, such as cocaine and amphetamines, increase dopamine levels in the brain's reward center, this creates strong salience that overcome becomes independent of the subjective experience of pleasure, which often diminishes as we build tolerance to the drug of choice. This is why it is hard to quit drugs cold turkey, your brain tells you you can’t live without them (evolutionary fitness via strong incentive salience signals), even long after the pleasure fades.
In response to the increase in tolerance, most people go up on the dose of the drug that they consume. This is often dangerous and life-threatening but the dopamine gradient is positive again so the decision-making here is clouded by this rebound. In the last stage of addiction, the individual’s mesolimbic system becomes completely restructured so that even things that were previously rewarding stop having any measurable effect.
Any individual dealing with serious substance addiction should be looked at with humanity and compassion, because from a neuroscience perspective, their predicament ends up being pure hell.
It is important to note that not all drugs of abuse have the same effect on the brain. However, the role of dopamine in the development of addiction is a common theme among many drugs of abuse. I would encourage anyone to read more about the specifics of this if interested!
Resetting Dopamine sensitivity
To end on a positive note, here are a few things that have been shown to help:
Ascetism and prolonged fasting periods (proven).
Therapy and meditation (hunch, except CBT).
Exercise: Exercise has been shown to increase dopamine levels in the brain and can help to reset dopamine sensitivity (proven).
Nutrition: A healthy diet that is rich in nutrients such as omega-3 fatty acids, B vitamins, magnesium and zinc can support normal brain function and may help to reset dopamine sensitivity (hunch?).
Thanks for reading.
Until next time, be well!
Ts