Anatomy Of A Frazzled Brain
I don’t usually write about animal studies because it’s always dicey extrapolating from rats to people, but this is a very interesting experiment that gives us a glimpse into how working memory operates:
“Working memory is short-term and flexible, allowing the brain to hold a large amount of information close at hand to perform complex tasks,” explains Rick Nauert on PsychCentral. “Without it, you would have forgotten the first half of this sentence while reading the second half. The prefrontal cortex is vital to working memory.
‘In many respects, you’d look pretty normal without a prefrontal cortex,’ says Dr. Craig Berridge, UW–Madison psychology professor. ‘You don’t need that part of the brain to hear or talk, to keep long-term memories, or to remember what you did as a child or what you read in the newspaper three days ago.’ But without your prefrontal cortex you’d be unable to stay on task or modulate your emotions well. ‘People without a prefrontal cortex [because of disease or injury] are very distractible,’ Berridge says. ‘They’re very impulsive. They can be very argumentative.’
The neurons of the prefrontal cortex help store information for short periods. Like a chalkboard, these neurons can be written with information, erased when that information is no longer needed, and rewritten with something new.
It’s how the neurons maintain access to that short-term information that leaves them vulnerable to stress, said David Devilbiss, Ph.D., a neuroscientist working with Berridge and lead author on the study, which is published in the journal PLOS Computational Biology.
Researchers used a new statistical modeling approach to show that rat prefrontal neurons were firing and re-firing to keep recently stored information fresh. ‘Even though these neurons communicate on a scale of every thousandth of a second, they know what they did one second to one-and-a-half seconds ago,’ Devilbiss said. ‘But if the neuron doesn’t stimulate itself again within a little more than a second, it’s lost that information.’
Apply some stress — in the researchers’ case, a loud blast of white noise in the presence of rats working on a maze designed to test working memory — and many neurons are distracted from reminding themselves of … what was it we were doing again?
‘We’re simultaneously watching dozens of individual neurons firing in the rats’ brains, and under stress those neurons get even more active,’ said Devilbiss.
‘But what they’re doing is not retaining information important to completing the maze. They’re reacting to other things, less useful things.’” Read more here.
We’ve likely all had the experience of being stressed out and finding that as a result, we keep forgetting what it is we were doing or saying. Fascinating that scientists are beginning to unravel the process by which this happens in the brain (even if it’s in the brain of a rat).