This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General physiology, Subject name: Physiology
Which of the following can act as both excitatory and inhibitory neurotransmitter? 
Select and explain. 
A. Acetylcholine, B. Glutamate, C. Norepinephrine, D. Dopamine
D: Dopamine
Answer: D: Dopamine 
Explanation: The dopamine is believed to act as an inhibitory transmitter in the basal ganglia, but in some other areas of the brain, it is possibly excitatory. It also functions as a stabilizer under some conditions.Ref: Guyton; 13th edition; Chapter 57 Contributions of the Cerebellum and Basal Ganglia to Overall Motor Control