July 8, 2016
(Wired) – The most sophisticated, widely adopted, and important tool for looking at living brain activity actually does no such thing. Called functional magnetic resonance imaging, what it really does is scan for the magnetic signatures of oxygen-rich blood. Blood indicates that the brain is doing something, but it’s not a direct measure of brain activity. Which is to say, there’s room for error. That’s why neuroscientists use special statistics to filter out noise in their fMRIs, verifying that the shaded blobs they see pulsing across their computer screens actually relate to blood flowing through the brain. If those filters don’t work, an fMRI scan is about as useful at detecting neuronal activity as your dad’s “brain sucking alien” hand trick. And a new paper suggests that might actually be the case for thousands of fMRI studies over the past 15 years.
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