Biophysicist Ilya Nemenman, left, is developing theories about the brain that can be tested in the lab of biologist Sam Sober, right. (Emory Photo/Video).
By Carol Clark
How does the brain correct mistakes and guide the process of learning a skill? Why do some individuals learn faster than others?
Two Emory researchers – biophysicist Ilya Nemenman and biologist Sam Sober – recently received a $1 million grant from the National Institutes of Health BRAIN Initiative to explore these questions through a theoretical-experimental framework. Their research into how the sensory-motor loop controls and optimizes learning could lead to better protocols to help those dealing with major disruptions to their learned behaviors, such as when recovering from a stroke.
The BRAIN Initiative (Brain Research through Advancing Innovative Neurotechnologies) was launched by President Obama in 2014 as part of a widespread effort to gain fundamental insights for treating a range of brain disorders.
Emory has received other grants from the BRAIN Initiative: In 2015, a $1.7 million award went to neuroscientists Dieter Jaeger (Department of Biology) and Garrett Stanley (Emory-Georgia Tech’s Wallace H. Coulter Department of Biomedical Engineering). They will use the award to explore neural circuits related to sensing and physical action. In 2016, neurosurgeon Robert Gross in the School of Medicine received a $5 million grant to focus on optimizing neurostimulation therapies for epilepsy.
The grant received by Nemenman and Sober is part of a new cohort, opening another phase of the BRAIN Initiative: The development of theoretical, computational and statistical tools.
“Big data by itself is not useful,” Nemenman says. “We also need to come up with methods for understanding such data.”
Nemenman is working on a theory to help explain how the brain learns. “If you are learning something similar to something that you already know, it’s easier than if you are learning something entirely new,” he says. “We see this effect across the animal kingdom, including in humans. And this ability to learn something new changes with age.”
He gives the example that he will always speak English with an accent, since he is a native of Belarus and did not move to an English-speaking country until shortly before he became a student at Princeton. His children, however, will speak English without an accent since they were born in the United States and immersed in English from birth.
Nemenman is collaborating with Sober, who conducts experiments with Bengalese finches. “These songbirds are one of the best model systems available for studying how the brain learns to communicate,” Sober says.
The male songbirds sing to attract a mate, but they are not born with this ability, Sober explains. Instead, the young males learn to sing by memorizing, and then imitating, the singing of their fathers. When a young bird sings the wrong note, it tries to correct its mistake to match the memorized “target” sound.
In experiments, the Sober lab places tiny earphones on a songbird. When the bird sings, the researchers distort some of the notes slightly and play back the sound through the earphones. The bird is tricked into thinking it has sung a note incorrectly and tries to correct it.
Through this method, the lab has found that the birds are able to correct small distortions of sound, but they cannot correct large distortions.
“Many errors are distributed as a bell-shaped curve, but the distribution of singing errors in the birds is not bell-shaped,” Nemenman says. He is developing theories to explain how the difficulty of learning and correcting for large disturbances is related to this peculiar shape of the distribution of errors produced by the brain during learning.
“We can test the theories through experiments and learn more about the process,” he says. “The ultimate goal is to develop predictive models of how individuals learn from their errors that can be extended to other organisms, including humans.”
Nemenman also recently received a grant from the Kavli Foundation, to support workshops, symposiums and journal clubs that foster interdisciplinary theoretical and computational approaches to neuroscience, and bridge researchers at Emory and Georgia Tech.
It is important for physicists to share their expertise and collaborate with other scientists focused on understanding the brain, Nemenman says. As chair of the American Physical Society’s division of biological physics, he strives to establish programs that attract young physicists to neuroscience.
“Physicists are well posed to have a dramatic impact in this area,” he says. “We are trained to do science by combining theory and experiments. We can apply the same techniques to study the brain that we use to study other mysteries of the universe. Many graduate students in physics who came in intending to work on string theory, like I did, are coming out with a PhD focused on theoretical neuroscience.”
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