New findings by Carnegie Mellon University, the University of California, Los Angeles and the University of California, Irvine, show how one component of the brain's circuitry - inhibitory neurons - behave during critical periods of learning.
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 cognitive functioning.
About 80 percent of neurons are excitatory. Traditional scientific tools only allowed scientists to study the excitatory neurons.
Sandra J. Kuhlman, assistant professor of biological sciences at Carnegie Mellon and member of the joint Carnegie Mellon/University of Pittsburgh Center for the Neural Basis of Cognition, said that they knew from previous studies that excitatory cells propagate information.
She said that they 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.
Kuhlman said that since they couldn't study the cells, we could only hypothesize how they were behaving during critical learning periods.
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.
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 inhibitory neurons didn't fire more as had been expected. They fired much less frequently - up to half as often.
The study has been published in the journal Nature.
--ANI (Posted on 27-08-2013)