Answer:
Cholinergic systems which are an organisation of nerve cells that uses acetylcholine in communicating nerve impulses are found everywhere in the human central nervous system.
It is speculated that they are crucial to learning, attention, memory, speaking and carrying out purposive movements. This is because of their high density in the thalamus, striatum, limbic system, and neocortex.
Cholinergic agents are biochemical compounds which produce the same effects as acetylcholine and/or butyrylcholine.
Studies show that the parasympathetic nervous system (which comprise of the rest and digest system and conserves energy decelerating the heart rate, accelerating intestinal and gland activity etc) uses acetylcholine to a great extent to communicate its messages and is said to be mostly cholinergic.
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