Which neurotransmitter is abbreviated as ACh and important for muscle action and memory?

• A. GABA
• B. Dopamine
• C. Acetylcholine (ACh)
• D. Serotonin

Answer: (C)

Acetylcholine, abbreviated ACh, is the neurotransmitter involved in both muscle action and memory. At the neuromuscular junction, motor neurons release acetylcholine, which binds to receptors on muscle fibers and triggers contraction by depolarizing the muscle membrane. In the brain, acetylcholine supports learning and memory through cholinergic pathways in regions such as the hippocampus and cerebral cortex; declines in these pathways are linked to memory disorders like Alzheimer's disease. The other neurotransmitters listed have different primary roles—GABA mainly provides inhibition to calm neural activity, dopamine is key for reward and motor control, and serotonin influences mood and other functions—so they are not associated with being abbreviated as ACh.