It’s well known, for example, that when submerged in cold water, the body slows its heart rate and restricts blood flow to the extremities in order to conserve oxygen for the vital organs and the brain most of all. A pair of French neuroscientists, Pierre-Yves Plaçais and Thomas Preat, were curious, though—within the brain itself, are there some functions that shut down before others when resources are scarce? To find out, they withheld food from a type of small fruit fly called Drosophila—and they discovered that, faced with a shortage of energy, the flies stopped making certain types of long-term memories before others.
The results are published in the current issue of Science. Plaçais and Preat were interested in long-term memory formation because it’s a particularly energy intensive operation (or, as they put it, it “involves heavy metabolic machinery”). They found that the starving flies stopped putting resources into forming aversive long-term memories (memories of bad things happening, like electric shocks) before they stopped forming appetitive long-term memories (memories of finding something to eat). From a survival perspective this kind of triage makes perfect sense: If you only have the energy to remember one thing, let it be where you last had a meal.
The study design is as interesting as the conclusions. The researchers identified a pair of neurons in the Drosophilia brain that controls the formation of aversive long-term memories. They tinkered with those neurons in a group of the starving flies, forcing them to make aversive memories even when their energy-strapped brains would have preferred not to. The researchers found that the starving flies who’d been forced to make these memories survived 30 percent less long than flies that had been left alone—an indication of just how valuable this survival mechanism is.
So does it also work in humans? Plaçais and Preat write, “Many of the features at play in the fly are also involved in the regulation of mammalian [long-term memories].” It’s a comforting thought and maybe a useful one, too: Next time you’re anticipating an unpleasant experience that you don’t want to remember, try not eating beforehand.
Image courtesy of Bbski via Wikimedia Commons
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Leon Neyfakh is the staff writer for Ideas. Amanda Katz is the deputy Ideas editor. Stephen Heuser is the Ideas editor.
Guest blogger Simon Waxman is Managing Editor of Boston Review and has written for WBUR, Alternet, McSweeney's, Jacobin, and others.
Guest blogger Elizabeth Manus is a writer living in New York City. She has been a book review editor at the Boston Phoenix, and a columnist for The New York Observer and Metro.
Guest blogger Sarah Laskow is a freelance writer and editor in New York City. She edits Smithsonian's SmartNews blog and has contributed to Salon, Good, The American Prospect, Bloomberg News, and other publications.
Guest blogger Joshua Glenn is a Boston-based writer, publisher, and freelance semiotician. He was the original Brainiac blogger, and is currently editor of the blog HiLobrow, publisher of a series of Radium Age science fiction novels, and co-author/co-editor of several books, including the story collection "Significant Objects" and the kids' field guide to life "Unbored."
Guest blogger Ruth Graham is a freelance journalist in New Hampshire, and a frequent Ideas contributor. She is a former features editor for the New York Sun, and has written for publications including Slate and the Wall Street Journal.
Joshua Rothman is a graduate student and Teaching Fellow in the Harvard English department, and an Instructor in Public Policy at the Harvard Kennedy School of Government. He teaches novels and political writing.