Communication between neurones: Current concepts.

Neurotransmitters are chemicals which have the specific function of transferring information from one neurone to another at specific sites called synapses. This concept is discussed in relation to the experimental evidence which suggests that neurotransmitters may be released non synaptically and that certain neurones may utilise more than one transmitter substance. The term 'modulator' is also discussed and compared with what is understood to be a 'neurotransmitter'.