Acetylcholine was the first neurotransmitter to be discovered and is found primarily at sites throughout the nervous system. It is responsible for the transfer of information between nerve and muscle, either triggering or stopping the contraction of muscle. Acetylcholine also plays an important role in attention, learning and memory.Queensland Brain Institute. (n.d.). What are neurotransmitters? [online] Available at: https://qbi.uq.edu.au/brain/brain-physiology/what-are-neurotransmitters [Accessed 19 Nov. 2018]. National Center for Biotechnology Information. (n.d.). Acetylcholine. [online] Available at: https://pubchem.ncbi.nlm.nih.gov/compound/acetylcholine#section=Top [Accessed 19 Nov. 2018]. Kuo, I.Y. and Ehrlich, B.E. (2015). Signaling in muscle contraction. Cold Spring Harbor perspectives in biology, 7(2), p. 6023. Perlmutter, D. and Colman, C. (2004). The Better Brain Book. New York: Riverhead Books, p. 22.