Why are there different types of neurotransmitters?

Why do we have different types of neurotransmitters and how do they affect computation in the brain?

• So I understand that brain computes information by firing neurons, and we have excitatory and inhibitory neurotransmitters, and they can make neuron more or less likely to fire. But why do we have more than 2 types of neurotransmitters then? If neuron is either fires or not, and you can only make it either more or less likely - why different neurotransmitters affect cognition in many different ways? Can you please explain it in a simple terms =)

• Answer:

  No simple way to explain this, but it is very cool for sure.  The brain is a "pattern-generator" and the entire system together generates different patterns as the neurons fire.  If one synapse is a tiny bit slower or faster it can alter the entire cascading pattern.  Different neurotransmitters have different effects.  Some will spawn the creation of new receptors that alter synaptic strength and others will affect what quantity of what is in the cleft altering the firing rate of a synapse.  All of these synapses together with all of the variability creates an enormously large set of possible timing and pattern generation scenarios and these "percolate up" into our consciousness together as one system.  Even the length of an axon or a dendrite alters the patterns generated, the different neurotransmitters alter the patterns, the variability is quite incredible.  Neurotransmitters themselves alter the patterns present by how they alter the firing rates. All of this together is what lets us experience such a complete, high-density, and full experience within reality.