Understanding Dopamine's Role in Parkinson's Disease

With the improvements in functional brain imaging technology in 1990, there has been a boom in understanding the relation of various brain structures to mental abilities in both health and disease. These understandings would continue to improve, thus helping researchers to find out better and safer ways to treat various disorders of the most critical organ.

In the brain, various parts are predominantly engaged in controlling some kind of activities, cognition, and emotional functionalities. The brain stem is the most primitive part of the brain from an evolutionary point of view, while the cortex is comparatively new. Most of the vital life centers are located in the brain stem, as they are present in all mammals while areas like the frontal brain cortex are comparatively new and play an essential role in thinking, planning, and decision making. Most of the brain functionalities are carried out by various brain centers working in harmony with each other.

In order to work in harmony with each other, however, brain centers need to communicate to each other, and this is done with the help of chemicals called neurotransmitters. Various neurotransmitters have different roles in managing the brain functionality. Dopamine and serotonin are just two examples of these neurotransmitters, which play a role in neuronal communication, which is critical in the so-called reward pathway.

Understanding reward pathway and role of dopamine

Reward pathway is a collection of various brain centers that give a feeling of pleasure to us, they also help us to remember various experiences, motivate us, and help to make definite decisions. This reward pathway or pleasure centers help us to be associated with environmental stimuli that are good for us, thus ensuring our survival, but an imbalance in the reward pathway may lead to addiction and over-involvement in specific activities.

So how does this reward pathway function? Well, whenever humans feel pleasure, the neurotransmitter or modulator called dopamine is released. In reaction to pleasure, dopamine is produced in an area of the brain called ventral tegmental area (VTA). VTA is located in the mid-brain, and once VTA releases dopamine, it sends signals to many other parts of the brain.

One of the critical brain areas to which VTA sends dopamine is called the amygdala, an area of the brain that is strongly associated with various emotional reactions. It plays a central role in stress reaction, fear, anxiety, social interaction, emotional learning, and even sexual orientation.

VTA also sends a signal via dopamine to a brain structure called nucleus accumbens, which is one of the most critical parts of reward pathway. It also controls the body’s motor functions in reaction to pleasure stimuli.

Another area to which VTA sends dopamine is the prefrontal cortex. This is an area of the brain that is involved in planning and decision making, and it also helps to keep various emotional reactions in check.

Finally, the last major brain center that is stimulated by VTA via dopamine is the hippocampus. This area of the brain is responsible for long-term memory, thus based on earlier experiences, it can influence the mind, telling it to either engage or not to engage in the activity.