Zebrafish larvae without eyes or pineal glands can still respond to light using photopigments located deep within their brains. Published today (September 20) in Current Biology, the findings are the first to link opsins, photoreceptors located in the hypothalamus and other brain areas, to increased swimming in response to darkness, a behavior researchers hypothesize may help the fish move toward better-lit environments.
“[It’s a] strong demonstration that opsin-dependent photoreceptors in deep brain areas affect behaviors,” said Samer Hattar, who studies light reception in mammals at Johns Hopkins University but did not participate in the research.
Photoreceptors in eyes enable vision, and photoreceptors in the pineal gland, a small endocrine gland located in the center of the vertebrate brain, regulate circadian rhythms. But photoreceptors are also found in other brain areas of both invertebrates and vertebrate lineages. The function of these extraocular photoreceptors has been best studied in birds, where they ...
