Researchers Discover That Fear Smells Like Sugar to Fish
Posted on February 23, 2012
When a fish is injured the rest of the school will quickly take off in fear. The fish are tipped off by a mysterious substance known as Schreckstoff, which means "scary stuff" in German. Researchers have discovered that Schreckstoff is actually a chemical mixture that contains a special type of sugar. When fish are injured they release fragments of a sugar known as chondroitin sulfate. The release of this sugar sets off alarm bells in nearby fish.
Suresh Jesuthasan of A*Star's Neuroscience Research Partnership and the Duke/National University of Singapore Graduate Medical School in Singapore says, "Our results provide a solution to a 70-year-old puzzle: the nature of this alarm signal."
Chondroitin sulfate is a major component of fish skin. Jesuthasan says its breakdown is likely triggered by enzymes when a fish sustains an injury. The new study by Jesuthasan's team shows that Schreckstoff and these sugar fragments register in a particular part of the zebrafish brain. That region in the scent-processing olfactory bulb includes an enigmatic class of sensory neurons known as crypt cells. The researchers believe these neurons may be specialized to detect the sugary alarm cue released by an injured fish.
Jesuthasan says, "This region of the olfactory bulb has unique projections to higher centers of the brain, so there may be a special circuit mediating aspects of the innate fear response."
The research was published here in Current Biology.