I have yet to find an adequate explanation to this question: "Why are there so many neurotransmitters?". It makes sense to me to only use the neurotransmitter that transfers the signal the fastest. I would also like to ask a few other brief questions just for clarity. Can multiple different kinds of neurotransmitters be found within a single synaptic knob? Can multiple different kinds of neurotransmitters be found within a single neuron? Here is a very typical, common response: "Different kinds of neurotransmitters are used to transmit different types of information (i.e. touch, taste, sight)". This does no good unless you can show how the information is distinguished from other information every step of the way. As information travels through the axon as an electrical signal, does it still have a specific identity? Does a specific neurotransmitter being released trigger the next neuron to release the same neurotransmitter? The only way that could be possible is if a single axon acted as if it contained multiple wires rather than just being a single wire. From my understanding, that is not the case. Here is another common answer: "Different neurotransmitters are used to avoid getting mixed signals". I also don't see why mixed signals would occur if since the process of one neuron signaling another takes place within the synapses. I will accept this as an answer if it can be shown that a sufficient number (in relation to the amount required to fire the neuron) of neurotransmitters actually do escape the synapse and wind up in another synapse. Another answer I came across is that the body has a use for neurotransmitter that act slower. For example: sustaining moments of (insert a feeling) for longer periods of time. Generally this role is given to hormones as they would accomplish this better, and even with that said, your actual experience only happens in hindsight. Whether an experience feels longer or not doesn't necessarily have to do with how instantaneously you experienced it, it has to do with how much information about that experience was committed to your memory. So which is it, or is it something else entirely?