Which neurotransmitter is associated with movement, planning, and reward, and has receptors that die in Parkinson's disease?

Dopamine is the neurotransmitter that plays a critical role in movement, planning, and reward pathways in the brain. It is primarily associated with the regulation of motor control and coordination, making it essential for fluid movements. The dopaminergic system is also heavily implicated in the brain's reward mechanisms, influencing feelings of pleasure and motivation linked to achieving goals.

In the context of Parkinson's disease, the neurons that produce dopamine, particularly those in the substantia nigra part of the brain, degenerate over time. This loss leads to the hallmark symptoms of Parkinson's, which include tremors, rigidity, and bradykinesia (slowness of movement). The depletion of dopamine disrupts the normal functioning of the basal ganglia, which is crucial for coordinated movement.

Other neurotransmitters mentioned do play significant roles in the brain but are not primarily linked to the symptoms and neurodegeneration seen in Parkinson's disease. For instance, serotonin is involved in mood regulation and sleep but does not have the same direct influence on motor control. Glutamate serves as the principal excitatory neurotransmitter in the brain, while endorphins are related to pain relief and pleasure but are not directly associated with the motor functions affected in Parkinson's disease.