Dopamine is the critical neurotransmitter for reward. Cocaine administration increases metabolism in the substantia nigra (SN), which can explain the altered motor function seen in cocaine-using subjects. However, cocaine is even more active in the dopaminergic neurons of the ventral tegmental area (VTA) than the substantia nigra. (Joan M. Lakoski, Joan M., et al. Cocaine. Telford Press, 1991.)
Five brain chemicals that act together to call the brain to attention and produce a sharp attentive state (dopamine, histamine, norepinephrine, acetylecholine, and serotonin). Any imbalance in production or distribution of any of these will zap the brain’s ability to act alertly. Stimulants such as amphetamines and cocaine act on all of these except acetylcholine. (Guiffre, Kenneth, MD, with Theresa Foy DiGeronimo. The Care and Feeding of Your Brain. p 30-39. NJ:Career Press, 1999.)
First use of cocaine may increase rush of pleasure 500 times that of the brain’s normal experience. Second use the pleasure may drop to 200 times. Third use the brain may release only 100 times the amount of dopamine in response. The promise of pleasure entices but the pleasure is less each time the drug is used. (Jensen, Eric. Brain-Based Learning. p 265. CA:The Brain Store, 1995, 2000.)
Two studies have linked ADHD with a deficiency of dopamine in the brain. This may be one reason for higher risk for substance abuse in people with ADHD as they attempt to self-medicate their brains. (Amen, Daniel, MD. The Brain in the News, Amen Clinic Newsletter. August, 2007.)
Conclusions from a groundbreaking study conducted by a team at the University of Central Florida indicate that some children (e.g., those diagnosed as ADHD) really DO need to move (fidget) in order to learn. The current educational model of sit down, be still, and be quiet does not work for these individuals. (Shrieves, Linda. Kids with ADHD need to fidget. http://www.physorg.com/news162554898.html)
Psychadelics (e.g., LDS, MDMA or Ecstasy, PCP, Special K) initially enhance dopamine and serotonin release in the brain. With chronic or high-dose usage however, the brain “spaces out” due to depleted levels of serotonin and a toxic effect on dopamine neurons. (Guiffre, Kenneth, MD, with Theresa Foy DiGeronimo. The Care and Feeding of Your Brain. p 33-39. NJ:Career Press, 1999.)
Dr. Daniel Amen has recommended to parents that children spend no more than 30 minutes a day playing video games. This is because (according to brain imaging studeis), video games impact the same area of the brain as cocaine and methamphetamine. When you play video games your brain really likes it because the process increases the amount of dopamine being released in the brain. "When you try to take those games away from them (the kids), they get really upset. In fact, some even go through withdrawal symptoms when they aren’t allowed to play.) According to Dr. Amen, this is because playing video games release much dopamine that there isn’t enough of the chemical available for the little things in life. Other activities and relationships that would normally make your children happy leave them feeling nothing at all. (Amen, Daniel, MD) (http://www.amenclinics.com/blog/3500/how-video-games-are-like-cocaine/)
Refer to Neurons and Neurotransmitters for additional information.