Final answer:
The tremors seen in Parkinson's disease are primarily due to a deficiency of the neurotransmitter dopamine caused by the degeneration of dopaminergic neurons in the substantia nigra.
Step-by-step explanation:
The deficiency in the neurotransmitter dopamine is responsible for the tremors seen in Parkinson's disease. In Parkinson's disease, there is a progressive loss of dopaminergic neurons in the substantia nigra, a midbrain structure crucial for regulating movement. This loss results in symptoms such as tremors, slowed movement, speech changes, balance and posture problems, and rigid muscles. Although recent research has implicated glutamate excitotoxicity in Parkinson's disease pathology, the primary issue is the reduction of dopamine, which leads to an imbalance in neurotransmission and contributes to the characteristic motor symptoms of the disease.