Stop or go…inhibit or excite? There seems to be some confusion regarding the claim that dopamine is a neuro-inhibitor in the dopamine addiction model, leading some people to have difficulty with the excitatory / inhibitory thing. Let me see if I can offer some clarification.
Excitatory means turning on, or firing, or increasing the rate of firing of the neuron. In this context, the “dopaminergic” neuron or, dopamine sensitive neuron. Inhibitory means the opposite: to turn off, or decrease the rate of firing of the neuron.
So whether dopamine excites the neuron, or turns it off depends on the receptor. When speaking about whether the neuron’s effect is to excite, or inhibit, in the sense of alertness, or dullness, it would probably be more appropriate, nevermind less confusing, to view it as character, or quality of effect, rather than excitory, or inhibitory (for instance, whether this dopaminergic character, and quality is trance-like, as opposed to alertness), perhaps as a function of pathway, or whatever else.
In this light, I think anyway, the question raised is whether ADHD is a result of increased XOR decreased dopamine type neuron activity — that is, does turning off dopamine neurons give ADHD like symptoms, or does more of them being turned on give ADHD type symptoms. The popular contention is there’s too many in the turned off category — thus the administration of cocaine-like dopaminergic stimulate.
I have come across an article or two showing increased learning, and concentration associated with increased dopaminergic activity. Still, there is a fine line between concentration, and trance — that’s how I’d view this particular instance of description of the dopaminergic stimulation character, and quality.
Most importantly though, if this dopaminergic quality is “inhibitory”, the obvious question is, with respect to what? What’s the dopaminergic neuron, having been turned on, inhibiting? Other neurons? Gets one or more of the dopamine circuits firing so as to limit other brain activity?
Again, concentration and trance, a fine line. Does it dampen other aspects of the central, and peripheral nervous system? This is, I think, the necessary direction of inquiry. So far, it does seem to go back to concentration, and trance. Dopamine seems to have the quality of pulling the organism together so to speak, neurally, and physically, and a part of this includes dampening excitability, and alertness.
This seems to naturally lead to a fine article in ‘psychology today’ by Kathleen McGowan:
Summary: Heroin and chocolate cake have a nasty way of crowding out the rest of the universe. The country’s chief addiction expert argues that the propensity to drink, overeat and take drugs is a matter of attention gone awry.
Some confusion with the meanings of the words: “excite” and “inhibit”, with respect to the action of dopamine, may be leading researchers to confuse “concentration” with slipping into a trance.