You're cruising down the highway, yakking via bluetooth with a business colleague and adding a few numbers in your head. In about two minutes you've got to steer over to the exit ramp. Don't forget about that. And don't forget who you're talking to. A lot of balls in the air, there.
But you've got an app for that. Called working memory, it sits inside your brain and juggles all those balls while you simultaneously navigate, negotiate, calculate and anticipate.
Like a computer’s RAM, working memory serves as a buffer where information, derived from the senses or retrieved from long-term memory, can be temporarily placed so the conscious brain can process it. It’s tied to assessments of cognitive capacity such as IQ, and to real-world outcomes such as academic performance.
In short, working memory is a big deal. You wouldn't want to leave home without it -- although if it's not working right, you just might. (I hate to say this, but -- as most people eventually find out -- working memory typically declines with age.)
So, where was I? Oh, yeah. The new study, led by Stanford psychiatrist neuroscientist Jong Yoon, MD, and published in the Journal of Neuroscience, showed -- for the first time -- that your ability to simultaneously hang on to several bits of information depends on the amount of a particular chemical in a particular part of your brain.
The chemical in question, called GABA, is a neurotransmitter: a substance that, passed in packaged packets from one nerve cell to the next in a relay, excites or inhibits the downstream nerve cell. GABA is the brain's most abundant inhibitory neurotransmitter.
The brain region Yoon's study focused on is called the dorsolateral prefrontal cortex. (Neuroscientists, cognizant of working memory's limitations, have thankfully coined the acronym DLPFC to denote this area.)
Proceeding from evidence that working memory can be deconstructed into key components, all coordinating closely but each (perhaps) operating through its own circuitry, Yoon and his colleagues designed a set of tasks that teased apart three important components: load (the number of separate bits of information your working memory can store at once), maintenance (how long the info can be stored before it fades away), and distraction resistance (how well the storage persists in the face of interfering stimuli).
Brain-imaging tests showed that the study participants that performed best on tasks requiring a high load capacity were, specifically, the ones with the most GABA in their DLPFCs.
Working memory is notoriously deficient in some neuropsychiatric conditions, including Alzheimer's disease -- and, profoundly but less widely realized -- schizophrenia. In his clinical practice, Jong works extensively with schizophrenic patients. He says the discovery not only helps to clarify at least one aspect of the brain’s mysterious ways but could, someday, help guide carefully aimed therapies for those patients, along with others whose working memory can stand improvement.
And whose couldn’t?
Previously: Found: A novel assembly line in brain whose product may prevent alcoholism, The brain makes its own Valium: Built-in seizure brake? and The reefer connection: Brain's own "internal marijuana" signaling system implicated in very early stages of Alzheimer's pathology
Photo by DirkJan Ransijn