What’s the deal with dopamine?

13 March 2013 by Pete Etchells, posted in News, SpotOn

As part of Brain Awareness Week, March’s SpotOn NYC (#SoNYC) event will look at the challenges of conveying the knowns and unknowns of neural disorders to the public. Preparing for the conversation, SpotOn is hosting a collection of related guest blog posts; contributions will examine the way brain research is communicated to the public and how this research is interpreted by the press. You can join in the online conversation by following the #BeBraiNY and #SoNYC hashtags. This post originally appeared here on March 12th, 2013. 

Ingredients: eight carbon atoms. Eleven hydrogen atoms. One nitrogen atom. Two oxygen atoms. Mix together well, and bake for 45 minutes at 200 degrees or gas mark 6. For news stories, add a healthy dose of controversy. Best served with a pinch of salt.

Dopamine, at face value, is a pretty simple little chemical. What is surprising about it is how complex and varied its effects are on the body. When introduced to the kidneys, it can have a diuretic effect. It can be used to increase heart rate and blood pressure following heart failure. More commonly, it is implicated in various motivational and attentional processes in the brain – but even there, the story is not so simple. As Vaughan Bell has recently and brilliantly pointed out, dopamine can have varied – even opposite – effects, depending on the receptor it is interacting with. It can have different effects depending on the area of the brain it is activated in, and it can sometimes have different effects in the same brain area. What is perhaps also surprising then, is how this wonderful complexity gets completely lost in any news story that involves dopamine.

Back in January, an article appeared on the Forbes magazine website called “Addicted to bang: the neuroscience of the gun” (protip: guns don’t have a nervous system, and there aren’t any guns in our nervous system, so you can’t have a ‘neuroscience’ of it). Of the effects of dopamine on addiction, it had this to say:

“First, because the human brain evolved in an era of immediacy—when threats and rewards were of the lions, tigers and food variety—the dopamine circuitry has an inborn timing mechanism. If the reward follows the stimulus by roughly 100-200 milliseconds, it’s sitting in dopamine’s sweet spot. Firing a muzzle loader—for example—would certainly release dopamine, but it takes too long between multiple firings for a significant reward loop to be created. Firing an automatic weapon, though, sits close to the sweet spot—an assault weapon can fire a round every 100 milliseconds. Meaning not only are guns addictive, but automatic weaponry is far more addictive than most.”

So in other words, every time someone fires an automatic weapon, through the actions of dopamine as a reward chemical, they become increasingly and incrementally addicted to it. It plays well into the popular conception of ‘reward’. Usually when we think of reward, we think of something nice – you do a good deed at home, and to incentivise that behaviour, you get a chocolate. In the popular press, this is where the story for dopamine ends; something nice happens, which causes a flood of dopamine, which reinforces the behaviour and makes it more appealing. The more this happens, the more dopamine gets released, and the more likely you are to become addicted. It’s a neat and tidy, simple story, that sounds serious and probable because it involves a neurotransmitter that we know lots about.

The trouble is that because brains are really complex, there’s never going to be a one-to-one mapping between a particular neurotransmitter and a particular function or behaviour. Ed Yong’s response to the article put it best when he said it was a story about “derpamine” - dumbed down and stupid. So while we do know a considerable amount about dopamine, the effects that it has (even on motivation and addiction) are not simplistic. Scicurious has recently and eloquently explained research looking at how dopamine can also be released when you’re just expecting something nice to happen. And as John Salamone and Mercè Correa highlight in an excellent review article, it is also involved in ‘aversive’ motivations – in other words, the need to avoid things that you find unpleasant. And yes, dopamine can in some cases be considered to be a ‘reward’ chemical, but the caveat here is that there doesn’t appear to be any consensus in the scientific literature about what reward specifically means.

So all of this is going to be confusing to someone encountering dopamine for the first time, but the answer to that is not, as so often happens in the media, to dumb the story down. However, the reason for the sheer number of poor neuroscience articles out there goes deeper than that. In part, it’s because simple stories are more enticing than convoluted ones. It’s also, I think, because there’s a reluctance among the scientific community to engage people in difficult, complex issues, particularly about the brain – and this is a real shame. There are some fantastic people like Vaughan Bell, Scicurious and Neuroskeptic, who are doing a great job of explaining neuroscience in an interesting, engaging, and (critically) accurate manner, and it would be brilliant to see more researchers try their hand at it. It may not necessarily stop the onslaught of wishy-washy, “dopamine = pleasure”-type articles, but reactive and intelligent blogging can certainly help to redress the balance.

On the 14th March, SpotOn is hosting a session on ‘Communication and the Brain’ that will look at the challenges of explaining various aspects of the brain to the public, and I sincerely hope that the session inspires more neuroscientists to take up blogging. Part of the answer to those challenges is to be honest, and not feel the need to oversimplify research to the point that it’s basically wrong. Much the opposite, in fact – for example, the complexity of dopamine’s story highlights just how cool this simple little neurotransmitter is. Think about it for a second. Isn’t it amazing that a single chemical can have such profound and widespread effects on the brain and human behaviour – everything from motor control, to heart rate, to motivation? To me, that’s much more interesting than tediously mapping it onto a single function and not giving it a second thought.

2 Responses to “What’s the deal with dopamine?”

  1. neuroecology | Permalink

    dopamine = reinforcer (especially if it released when there is a 'prediction error'), it can just positively reinforce and negatively reinforce...

    (of course then we have to disambiguate reinforcement and motivation and that gets tricky too!0

  2. Rupert | Permalink

    I think Salamone might say that dopamine is important in many processes, of which motivation and reward are emergent processes.


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