It's been a bit crazy in the gamification world with GSummit and CHI coming one after the other, but I'm back and have been meaning to post on a topic that came up again and again at the GSummit. So often, in fact, that I started to think of the old drinking game Hi Bob because people were saying dopamine in practically every talk. It's funny to me, because my degree is in Cognitive Neuropsychology and as part of my qualifying exams, I had to map out the entire dopaminergic system. In fact, I might still have the notecards I drew out to study from in my garage someplace. Dopamine (and really all neurotransmitters involved in behavior) is a topic I studied a lot.
For those of you who aren't following why dopamine kept coming up at the GSummit, here's a little background. Dopamine is a neurotransmitter, or the chemical juice that lets one neuron (nerve) talk to another. The neurotransmitters break down into a set of categories, usually based on their chemical structure. The most common groupings are the amino acids (like glutamate, which is not the same as monosodium glutamate, but that's someone else's blog), peptides (like Substance P, a very science fiction-y name) and monoamines (like dopamine, histamine, and serotonin). Here's a lovely set of dopamine molecule earrings from our friend at madewithmolecules.com:
The brain, and the body in general for that matter, is fairly parsimonious with neurotransmitters and the same neurotransmitter might be involved in multiple very different systems. Dopamine is a prime example--it's the main neurotransmitter of the motor system (loss of neurons in the nigrostriatal pathway is the primary problem in Parkinson's disease) but it's also one of the main neurotransmitters of the mesolimbic system (the other is serotonin). The mesolimbic system is sometimes described as a "reward" pathway, which is why it kept coming up at the GSummit.
Why is dopamine maybe involved in reward? Well, that's an interesting question. Back in the 1950's, a couple of researchers (Olds and Milner) decided to see what would happen if the electrically stimulated a region of the brain in the mesolimbic system called the nucleus accumbens when a rat went into a certain region of their cages. Turns out, rats liked it. They liked it a lot. So much that when the experiment was adjusted so that they could press a lever to get the little zip of electricity, they'd do it as much as 1700 times an hour. And the nucleus accumbens is one of the structures in the mesolimbic system that uses dopamine to communicate. Initially, this area was described as a reward center and dopamine was hypothesized to be the neurotransmitter of pleasure. More evidence came from the discoveries that dopamine levels increase in the brain when addicts take drugs like opiates, cocaine and amphetamines. When dopamine is blocked in the brain by 99%, rats stop eating, which led researchers to hypothesize that they no longer derived any pleasure from eating.
But of course, nothing's ever quite that simple in neuroscience. Further research on the rats who had all their dopamine suppressed concluded that it wasn't that the rats didn't take pleasure in eating, it was just that they had no desire to eat on their own. If they pushed food on the rats, they concluded that they seemed to show pleasure while eating (though how they conclude that sort of escapes me) but that left to their own devices, they simply wouldn't eat. They had lost the motivation to initiate eating.
"Dopamine-depleted rats still ‘like’ rewards, and still know the rewards
they ‘like’. They simply fail to ‘want’ rewards they ‘like’."
Berridge and Robinson, 1998
Further experiments with people confirmed the idea that dopamine might not be about pleasure and reward as much as it created a wanting or motivation to keep seeking out stimulation. There is some evidence that dopamine levels increase when a reward is
greater than expected, which then is hypothesized to increase drive or
motivation to achieve a reward. Lack of dopamine meant there was no motivation or drive to do something.
So the role of dopamine might not be in pleasure/reward after all but in motivation and drive. Still pretty important issues for gamification, just maybe not in the way some folks might have thought.