Researchers discover how inhibitory neurons behave during critical periods of learning

August 25, 2013, Carnegie Mellon University

We've all heard the saying "you can't teach an old dog new tricks." Now neuroscientists are beginning to explain the science behind the adage.

For years, neuroscientists have struggled to understand how the microcircuitry of the brain makes learning easier for the young, and more difficult for the old. New findings published in the journal Nature by Carnegie Mellon University, the University of California, Los Angeles and the University of California, Irvine show how one component of the brain's —inhibitory neurons—behave during critical periods of learning. The paper is available online as an Advance Online Publication.

The brain is made up of two types of cells—inhibitory and excitatory neurons. Networks of these two kinds of neurons are responsible for processing sensory information like images, sounds and smells, and for . About 80 percent of neurons are excitatory. Traditional only allowed scientists to study the excitatory neurons.

"We knew from previous studies that excitatory cells propagate information. We also knew that inhibitory neurons played a critical role in setting up heightened plasticity in the young, but ideas about what exactly those cells were doing were controversial. Since we couldn't study the cells, we could only hypothesize how they were behaving during critical learning periods," said Sandra J. Kuhlman, assistant professor of at Carnegie Mellon and member of the joint Carnegie Mellon/University of Pittsburgh Center for the Neural Basis of Cognition.

The prevailing theory on inhibitory neurons was that, as they mature, they reach an increased level of activity that fosters optimal periods of learning. But as the brain ages into adulthood and the inhibitory neurons continue to mature, they become even stronger to the point where they impede learning.

Newly developed genetic and are now allowing researchers to visualize inhibitory neurons in the brain and record their activity in response to a variety of stimuli. As a postdoctoral student at UCLA in the laboratory of Associate Professor of Neurobiology Joshua T. Trachtenberg, Kuhlman and her colleagues used these new techniques to record the activity of inhibitory neurons during critical learning periods. They found that, during heightened periods of learning, the didn't fire more as had been expected. They fired much less frequently—up to half as often.

"When you're young you haven't experienced much, so your brain needs to be a sponge that soaks up all types of information. It seems that the brain turns off the inhibitory cells in order to allow this to happen," Kuhlman said. "As adults we've already learned a great number of things, so our brains don't necessarily need to soak up every piece of information. This doesn't mean that adults can't learn, it just means when they learn, their neurons need to behave differently."

Explore further: Scientists learn more about how inhibitory brain cells get excited

More information: Paper: http://dx.doi.org/10.1038/nature12485

Related Stories

Scientists learn more about how inhibitory brain cells get excited

January 30, 2013
Scientists have found an early step in how the brain's inhibitory cells get excited.

Distinct brain cells recognize novel sights

April 11, 2012
No matter what novel objects we come to behold, our brains effortlessly take us from an initial "What's that?" to "Oh, that old thing" after a few casual encounters. In research that helps shed light on the malleability of ...

New learning and memory neurons uncovered

April 11, 2013
(Medical Xpress)—A University of Queensland study has identified precisely when new neurons become important for learning.

Re-learning how to see: Researchers find a crucial on-off switch in visual development

August 1, 2013
A discovery by a University of Maryland-led research team offers hope for treating "lazy eye" and other serious visual problems that are usually permanent unless they are corrected in early childhood.

'Should I stay or should I go?' Neuroscientists link brain cell types to behavior

May 26, 2013
Neuroscientists from Cold Spring Harbor Laboratory, led by Assistant Professor Adam Kepecs, have linked the activity of two types of brain nerve cells, neurons, to decisions made during particular type of behavior. The team ...

Mapping blank spots in the cheeseboard maze

March 22, 2013
(Medical Xpress)—During spatial learning, space is represented in the hippocampus through plastic changes in the connections between neurons. Jozsef Csicsvari and his collaborators investigate spatial learning in rats using ...

Recommended for you

Neuroscientists suggest a model for how we gain volitional control of what we hold in our minds

January 16, 2018
Working memory is a sort of "mental sketchpad" that allows you to accomplish everyday tasks such as calling in your hungry family's takeout order and finding the bathroom you were just told "will be the third door on the ...

New study reveals why some people are more creative than others

January 16, 2018
Creativity is often defined as the ability to come up with new and useful ideas. Like intelligence, it can be considered a trait that everyone – not just creative "geniuses" like Picasso and Steve Jobs – possesses in ...

Even without nudging blood pressure up, high-salt diet hobbles the brain

January 16, 2018
A high-salt diet may spell trouble for the brain—and for mental performance—even if it doesn't push blood pressure into dangerous territory, new research has found.

Brain imaging predicts language learning in deaf children

January 15, 2018
In a new international collaborative study between The Chinese University of Hong Kong and Ann & Robert H. Lurie Children's Hospital of Chicago, researchers created a machine learning algorithm that uses brain scans to predict ...

Preterm babies may suffer setbacks in auditory brain development, speech

January 15, 2018
Preterm babies born early in the third trimester of pregnancy are likely to experience delays in the development of the auditory cortex, a brain region essential to hearing and understanding sound, a new study reveals. Such ...

BOLD view of white matter

January 15, 2018
The brain consists of gray matter, which contains the nerve cell bodies (neurons), and white matter, bundles of long nerve fibers (axons) that until recently were considered passive transmitters of signals between different ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.