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Dopamine does it again, and again… and again.

I have four email addresses. I’ve checked each three times in the last hour. Bold text in my inbox never…

By Kevin Sauve , in Grey matter: A blog about the brain and behaviour , on January 14, 2009

I have four email addresses. I’ve checked each three times in the last hour. Bold text in my inbox never seems quite as exciting as when there is work that needs to be done, even if that means that I’ve just discovered more work.

Either that or checking the refrigerator, repeatedly. It seems that a belief in spontaneous generation, of the kind purposed by the seventeenth century scientist Jean Baptiste van Helmont, who insisted that mice would spring into existence by wrapping cloth in wheat germ, makes logical sense to the procrastinator.

None-the-less, while deliberating on whether to begin this blog or check the icebox one more time, I came to my senses and abandoned spontaneous generation as a possibility and left to buy more milk.

Conveniently traversing the magazine aisle, two words caught my attention, “Procrastinating Again?”. After a quick double take and an anxious wait in the check-out line, I had the topic for my first blog.

The most recent edition of Scientific American MIND delights in the biology of deferment, a dawdling science writers dream come true. It turns out that the ubiquitous neurotransmitter, dopamine, plays a significant role in promoting procrastination. Which doesn’t seem all that remarkable when one considers the reputation dopamine has in encouraging addictive behaviour.

Perhaps a little explanation of the research is in order.

Addictive substances work by signalling the reward system in the brain that utilizes our good friend dopamine. Under normal circumstances, say biting into an ordinary looking apple that just so happens to be the best apple you’ve ever had, this reward system encourages you to repeat the behaviour and seek out another apple that looks the same, an obvious evolutionary advantage.

Addictive drugs bind to receptors that signal the release of dopamine and flood the reward system with elevated levels of it. Even if smoking that first cigarette made you choke and gag, you can blame your brain for telling you that experience was a good one. Hence why people with addictions find it so hard to kick them, even if they hate them. It’s not so much that smokers can’t quit but, strictly physiologically speaking (whatever that means), they find little value in doing so.

When it comes to procrastination, the story is a little bit different. Led by neuroscientist Barry Richmond from the National Institute of Mental Health, a study conducted on monkey’s who were trained to hold and release levers for a juice reward were found to delay in releasing the lever more often if they knew the reward wasn’t coming any time soon. When a light signaled that the reward was close at hand most would perform the task faster and more accurately.

That was until Richmond turned some of the monkey’s into focused, compulsive lever releasing machines. Richmond injected a small molecule known as DNA antisense into the rhinal cortex of each primate, blocking the production of dopamine receptors and effectively nullifying the effect of the neurotransmitter on this part of the brain. Some of the neurons in the rhinal cortex are connected to neurons associated with the visual cortex and dopamine works between them, indicating that something that was seen may lead to a reward.

To summarize, without dopamine the monkeys had no idea when to expect the juice and so just kept plugging away at the task hoping that the next lever release would be the one to win the jackpot. They had no value in procrastination. In addiction, it’s arguable that without dopamine, lighting up a cigarette may be of as much value to a smoker as drinking rocket fuel.

So that beautifully complex concept of value that exists “in here” is related, at least in some sense, to a tiny and relatively simple molecule that exists “out there”. But regardless of where it exists, the intrinsic value I feel from writing this blog has been overwhelmed entirely by the fear of failure if I don’t. Perhaps dotting the end of this sentence with one final period may give me the dose of dopamine I need to get rolling on my next blog, that is, if after reading it I find it just a little bit better than expected.


  • Kev

    That dopamine sure is fun, but she’s no serotonin. Thanks for helping me procrastinate the proofreading of my blog. It is now 2:52 am.


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