Final answer:
Acetylcholine (ACh) is the neurotransmitter that is involved in muscle activation, learning, and memory. It functions at the neuromuscular junction and influences the cognitive processes related to memory formation.
Step-by-step explanation:
The neurotransmitter involved with the action of muscles, learning, and memory is acetylcholine (ACh).
Acetylcholine is a neurotransmitter released by motor neurons that binds to receptors in the motor end plate, triggering depolarization that is essential for muscle contraction. This process is vital at the neuromuscular junction, enabling motor neurons of the nervous system to activate muscles. In addition to its role in muscle action, acetylcholine is also implicated in various brain functions associated with learning and memory.
There is evidence indicating the participation of various neurotransmitters in memory, including acetylcholine, which is critical for developing new memories through neural communication and synaptic connections.