Friday, December 10, 2010

Tetris and the site-specific hypothesis

Right, so I said I would post a little more about the fairly recent paper "MRI assessment of cortical thickness and functional activity changes in adolescent girls following three months of practice on a visual-spatial task" by Haier et. al.

If you do a quick Google search for "tetris and cortical thickness" you'll find a number of popular articles, blog posts, and news items detailing the findings from the lab of Haier and his colleagues - great, but it seems as though most of them have missed something important. Everyone is going on about brain thickness and efficiency (a concept that doesn't seem to be nearly as straightforward as the blogosphere makes it seems - more on this soon) and yet they almost all skip over one of the major findings as if it were an added extra.

I don't want to spend time going over the same ground as the hundreds of items you'll find online - but I do think that I can add something that seems to have been mostly overlooked.

take another look at the abstract :-
Neuro-imaging studies demonstrate plasticity of cortical gray matter before and after practice for some motor and cognitive tasks in adults. Other imaging studies show functional changes after practice, but there is not yet direct evidence of how structural and functional changes may be related. A fundamental question is whether they occur at the same cortical sites, adjacent sites, or sites in other parts of a network.
now carefully reread the last line and you'll see that they're not only interested in whether there are structural (thickening of the cortex) or functional (Haemodynamic response) changes, these facts had already been established in earlier studies but are interested in exploring what they call the site-specific hypothesis, the idea that when structural and functional changes occur in the brain, they'll tend to happen in roughly the same places.
Their investigations show that, in this case at least, the site-specific hypothesis doesn't seem to hold as there was almost no overlap between changes in BOLD (blood oxygen level dependent) changes and increases of cortical thickness (there were also no measured decreases in cortical thickness).

This is a pretty cool fact.

Of course I'm not saying that the results that there were structural and functional changes aren't interesting in themselves - especially considering what they've revealed about the areas that were affected through tetris practice. It's just easy to overlook a fairly interesting and potentially significant fact in all the fuss being made over the fact that playing a computer game "can make your brain bigger and more efficient".

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