Wednesday, March 03, 2010

fMRI discoveries much less than sometimes hyped to be

Every so often, I find articles along the lines of "fMRI proves that area of the brain X is involved in activity Y". But, is that the case? How do we know that area X is processing activity Y directly? Couldn't it be the case that area X is processing something else triggered by activity Y, while merely 3 neurons process activity Y? We are not aware of all our brain is doing, how can we claim there is nothing else going on other than activity Y?

The main issue here is that all we see is activity. We do not know what the activity represents because we do not know how the brain encodes what is going on. Essentially, what we can perceive is ciphered conversations between neurons. From the traffic, we would like to infer the meaning of the traffic. But we can't do that with full confidence without breaking the code.

I actually verified this point of view with a neuroscience expert. And yes indeed, all we really have is correlations illustrated by nice fMRI graphics. Maybe not all experts think the same. And yet, although correlation is better than guessing, it's most likely still far away from proving (and supporting the hyped) causality.

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