Mentally exhausted? Study blames buildup of key chemical in brain

You know the feeling. You’ve been cramming for a test or presentation all day, when suddenly you can’t remember simple things, like what you ate for breakfast, or where exactly Belize is. Now, a study hints at why we get so unraveled after hours of hard mental labor: a toxic buildup of glutamate, the brain’s most abundant chemical signal. The study isn’t the first to try to explain cognitive fatigue—and it is bound to stir up controversy, says Jonathan Cohen, a neuroscientist at Princeton University who wasn’t involved with the work. Many scientists once thought doing difficult mental tasks used up more energy than easy tasks, exhausting the brain like exercise can do to muscles. Some even suggested drinking a sugary milkshake would make you mentally sharper than an artificially sweetened one, he says. But Cohen and many others in the field are skeptical of such simplistic explanations. “It's all been debunked,” he says. In the new study, researchers looked at whether levels of glutamate are related to behavior that so often manifests when we’re mentally exhausted. Seeking easy, immediate gratification, for example, or acting impulsively. Glutamate typically excites neurons, playing key roles in learning and memory, but too much of it can wreak havoc on brain function, causing problems ranging from cell death to seizures. The scientists used a noninvasive technique called magnetic resonance spectroscopy, which can detect glutamate through a...
Source: Science of Aging Knowledge Environment - Category: Geriatrics Source Type: research