Scanning Dead Salmon in fMRI Machine Highlights Risk of Red Herrings

[n2doc]

By Alexis Madrigal September 18, 2009 | 5:37 pm |



Neuroscientist Craig Bennett purchased a whole Atlantic salmon, took it to a lab at Dartmouth, and put it into an fMRI machine used to study the brain. The beautiful fish was to be the lab’s test object as they worked out some new methods.

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.”

If that were all that had occurred, the salmon scanning would simply live on in Dartmouth lore as a “crowning achievement in terms of ridiculous objects to scan.” But the fish had a surprise in store. When they got around to analyzing the voxel (think: 3-D or “volumetric” pixel) data, the voxels representing the area where the salmon’s tiny brain sat showed evidence of activity. In the fMRI scan, it looked like the dead salmon was actually thinking about the pictures it had been shown.

“By complete, random chance, we found some voxels that were significant that just happened to be in the fish’s brain,” Bennett said. “And if I were a ridiculous researcher, I’d say, ‘A dead salmon perceiving humans can tell their emotional state.’”

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.

more:

http://www.wired.com/wiredscience/2009/09/fmrisalmon/

[unpossibles]

1. the obvious conclusion:

OMG ZOMBIES ARE REAL! RUN!

[Aragorn]

2. SWIM !

in this case. Lots of artifacts get interpreted as "valid" - glad this is out.

[Ready4Change]

4. Note: It reacted to images of people.

People with living human braaaiiiiiinnnnnnnsssss!

[Igel]

3. Promptly forwarded to a psycholinguist

who, from time to time, sits on dissertation committees for students working with fMRI data.

[Indenturedebtor]

5. The real litmus would be to hook Palin up to an fMRI n/t

[Rabrrrrrr]

6. What it made me wonder immediate is "How long do brains take to shut down after death?"

Perhaps it had nothing to do with photos being shown, but maybe the brain just keeps firing after death ofr a few hours, days, or maybe weeks.