Final answer:
Nikki's Parkinson's disease is due to the degeneration of the Basal Ganglia, specifically the substantia nigra, where dopamine-producing neurons deteriorate, leading to motor and cognitive symptoms.
Step-by-step explanation:
Nikki's development of Parkinson's disease can be attributed to the degeneration of her Basal Ganglia. Parkinson's disease is a degenerative brain disorder that is caused by the progressive death of neurons in the midbrain, particularly in the substantia nigra. These neurons are responsible for producing dopamine, which is crucial for controlling muscle movement. As the dopaminergic neurons deteriorate, patients experience symptoms such as tremors, slowed movement, speech changes, balance and posture problems, and rigid muscles. Over time, the disease can also lead to cognitive symptoms including memory loss, depression, and dementia. The exact mechanism behind the neuronal degeneration is not fully understood, but the formation of protein structures called Lewy bodies and the loss of regulation of striatal neurons, contributing to an increase in glutamatergic activity, are implicated. The reduction in dopamine levels plays a central role in the motor symptoms associated with the disease.