Tuesday, September 22, 2009

Dead Salmon + MRI = Red Herring



Neuroscientist Craig Bennett bought a salmon to test an fMRI machine and work out some protocols.
So, as the fish sat in the scanner, they showed it “a series of photographs depicting human individuals in social situations.” To maintain the rigor of the protocol (and perhaps because it was hilarious), the salmon, just like a human test subject, “was asked to determine what emotion the individual in the photo must have been experiencing.”
The salmon, as Bennett’s poster on the test dryly notes, “was not alive at the time of scanning.”
Those involved got a laugh out of the situation, until the scans came back and showed that activity was detected in different areas of the brain when the fish was “shown” the pictures. Remember, the fish was dead.
The result is completely nuts — but that’s actually exactly the point. Bennett, who is now a post-doc at the University of California, Santa Barbara, and his adviser, George Wolford, wrote up the work as a warning about the dangers of false positives in fMRI data. They wanted to call attention to ways the field could improve its statistical methods.
Which is not to say that scans aren’t a useful research tool, but that they must be carefully monitored to avoid false positive results. (wired.com)


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