A reward pathway, or reward system, refers to a group of brain structures that are activated by rewarding stimuli.
The most crucial reward pathway in the brain is known as the mesolimbic dopamine system. Though there are other existing reward pathways, the dopamine reward system is a key detector of rewarding stimuli.
A series of experiments conducted by James Olds and Peter Milner in the 1950s were the first indication of reward pathways in the brain. These experiments involved implanting electrodes into the brains of rats. The rats then pressed levers which stimulated different areas of the brain.
Olds and Milner found that the rats repeatedly pressed the lever to receive stimulation to the front end of the brain called the corpus callosum.
It was determined that the corpus callosum is the most sensitive area of the brain, with rats pressing a lever over 7,500 times in 12 hours to receive electrical stimulation to that area of the brain.
This repetitive behavior was a strong indication that the rats were enjoying the stimulation. It is now understood that when our brain structures are exposed to rewarding stimuli, like drugs or alcohol, brains respond by increasing the release of the chemical, dopamine.
Addiction And The Brain: The Difference Between Natural And Artificial Rewards
Research into reward pathways has shown that the brain is hardwired to repeat rewarding behaviors as a survival instinct. Intrinsic rewards such as food, water, sex, and nurturing allow for feelings of pleasure while eating, drinking, copulating, and being nurtured.
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Each of these natural rewards are meant to inhibit human survival on a primal level. However, natural reward pathways can sometimes feel limited once someone is exposed to an artificial reward.
Artificial rewards release more substantial amounts of “feel-good” chemicals like dopamine and serotonin in the brain compared to natural rewards.
From Reward Pathway To Addiction: The Brain On Dopamine
How are the reward pathway and addiction linked? The more someone repeats a behavior, the more reinforced that behavior becomes, creating a feedback loop.
After a certain amount of time, physical changes occur in the brain, altering the reward pathway permanently. The amount of time it takes for such changes to occur depends on the type of substance being abused. This could be after one use or over the course of months.
Changes in the brain due to reinforced behavior are highly influential when a person transitions from casual use of a substance to addictive substance use.
The persistent release of dopamine during chronic drug use gradually rewires specific brain structures, embedding drug cues, which leads to obsessive cravings for the substance.
Addiction is a complex brain disease. However, at its core, addiction is a biological process, which is why substance use affects brain circuitry.
How Reward Pathways Contribute To Chronic Relapse
Multiple types of substances cause similar behavioral changes or addiction. This can be explained by the fact that all drugs produce common actions within the brain, such as activating the dopamine reward pathway.
Once this pathway is activated, it can lead to permanent changes in brain structure. These changes are what make withdrawal so difficult and recovery a life-long process.
Compulsive drug use can be a result of four overlapping brain regions or pathways, each with a distinctive pull toward substance abuse.
The four brain regions/networks that commonly lead to relapse include priming (single use that develops into a binge), drug cues, cravings, and stress.
The sections of the brain that instigate priming and drug cues also describe the mechanisms involved in addictive processes, which adds to the likeliness of an individual relapsing.
Recovering From Addiction With Effective Substance Abuse Treatment
Due to the hold reward pathways have over an individual’s actions, it can be nearly impossible to break free of an addiction cycle without support in treatment.
Treatment options will vary, depending on the severity of substance abuse. Adequate substance abuse treatment has proven to play a critical role in a person’s ability to stop addictive behaviors and restore control over their lives.
The most effective treatment types work to address the individual’s unique issues, including what caused them to begin substance abuse. By confronting both the mental and physical aspects of addiction, individuals are more likely to have a successful recovery outcome.