By "central", it would mean central nervous system as opposed to the peripheral nervous system. It wouldn't mean central parts of the brain but rather the whole central nervous system. Acetylcholine has lots of peripheral activities ranging from parastalysis of the gut (the rythmic movement in the gut that makes food pass through the digestion system) to things like rates of perspiration and how wet or dry mucous membranes are. It also affects CNS and affects more than memory, it effects conciousness itself and how you perceve the world.
I don't know if this info helps clarify it or not. Just pointing out what central is most likely referring to.
Edited by MrSpud, 31 January 2010 - 07:44 PM.