ABSTRACT
The cardinal symptoms of Parkinson’s disease (PD) are rest tremor, bradykinesia, rigidity, and postural instability. These features arise from the specific neurodegeneration of substantia nigra (SN) dopamine neurons in the mid-brain. The resultant dopamine deficiency, predominantly in the striatum, causes a wave of circuitry changes in the basal ganglia, thus producing the characteristic movement disorder.
