A 60-year-old man has resting tremor, pill-rolling movements, rigidity, and bradykinesia. Which of the following is most likely to be decreased in this man?
The clinical features points toward a diagnosis of Parkinson disease. It is characterized by loss of dopaminergic neurons that project from the substantia nigra to the putamen. Other options: Serotonergic raphe neurons have been implicated in the control of mood and descending pain modulation (analgesia) pathway. GABAergic pathway loss from striatum (caudate nucleus + putamen) results in hyperkinetic disorder, Huntington disease. Loss of nucleus basalis of Meyne in the basal forebrain, a diffuse cholinergic projection to the entire neocoex, the amygdala, and the hippocampus leads to Alzheimer disease.
Serotonin neurons in the raphe nuclei
GABA neurons in the caudate nucleus and putamen
Dopamine neurons in the substantia nigra
Acetylcholine neurons in the forebrain
Motor System