Why Did Researchers Put A Dead Fish In An fMRI?

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When research subjects enter an fMRI machine, which lets scientists analyze their brain activity, they often need to concentrate on holding very still. That wasn't a problem for the subject of Craig Bennett's 2009 study: it was a dead salmon, after all. It might seem strange to put something dead in a device that detects brain activity, but Bennett had a good reason. fMRI machines aren't foolproof, and he wanted to show other scientists how easy it was to accidentally interpret a false fMRI reading as real data. But just scanning a dead fish brain would be too simple. Instead, Bennett and his team treated the salmon like they would any human subject: they showed it pictures of people in social situations, and asked their subject to determine each person's emotions. Through each question and the fish's failure to answer, the fMRI scanned the tiny brain for signs of thought. The experiment worked: the fMRI actually found something that could be interpreted as evidence of brain activity. The team's study, "Neural correlates of interspecies perspective taking in the post-mortem Atlantic Salmon," was unfortunately rejected by several scientific journals, but its story lives on as a cautionary tale to any researcher who might analyze fMRI scans a little too carelessly.

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Key Facts In This Video

  1. CAT or CT Scans involve taking a series of X-ray images around the head and combining them to get an overall image. The resolution isn't very high, but they can be used to see major structural problems, like tumors. 00:13

  2. MRIs involve applying a combination of magnetic fields and radio-frequency energy waves to the brain, which cause hydrogen atoms to emit energy. The device reads this energy to create an image with higher resolution than a CT scan. 00:40

  3. fMRI uses a similar approach to MRI, but uses the contrasts between oxygenated and unoxygenated blood to identify changes of blood flow in the brain, and thereby identify its most active areas. 01:33

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