Serotonin as the habit signaller.

which neurochemical system is the most crucial for controlling the balance between more automatic and more deliberate cognitive processing? Based on previous research, my colleagues and I had a hunch that the serotonergic system might be a good place to look … what if serotonin was being used by our brains to digest information – that is, to process information flow between the distributed circuits of neurons required to identify, decide and act? … Any time there is a problem to be solved or a decision to be made, our brains must figure out which resources to deploy to meet the challenge … serotonin helps the brain continue with an automatic or habitual approach to a situation when that seems to be working well