Brain Mapping and Task Distribution

Sitting and thinking doesn’t mean that you are taking it easy. Your brain is using up about a quarter of the energy output of your metabolism and that energy consumption is pretty well steady whether we are daydreaming about our vacation or trying to solve some huge problem on our income tax form.

The large numbers of fMRI studies show which parts of the brain are getting particularly excited by different activities and we have got used to this sort of brain mapping. However, a paper in this week’s Proceedings of the National Academy of Sciences by Gonzalez–Castillo et al, argues that we are being a little short sighted here (1).

Their argument is that signal-to-noise levels have misled us to localize the interactions too much and that although we may have highly activated regions for particular tasks, very much more of the brain is involved across both hemispheres giving a much more inclusive picture than hitherto envisaged.

This doesn’t mean that previous visualization studies are incorrect, just that they are incomplete as their sensitivities were limited and we should think of more widely organized activity.

With the energy consumption being fairly constant as our little grey cells are all very busy whether we seem to have a thought in our head or not, it is clear that just thinking hard about going to the gym and eating a more healthy diet isn’t going to up our metabolic demand and we will just have to get exercising on the treadmills after all.


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