Researchers have for the first time precisely manipulated bursting activity of cells in the thalamus, tying it to the sense of touch. Shown are Georgia Tech graduate student Clarissa Whitmire and Professor Garrett Stanley. Photo: Rob Felt
As you start across the street, out of the corner of your eye, you spot something moving toward you. Instantly, your brain shifts its focus to assess the potential threat, which you’re relieved to determine is a slow-moving bicycle.
The brain’s ability to quickly focus on life-or-death decisions, then immediately shift to detailed analytical processing, is believed to be the work of the thalamus, a small section of the midbrain through which most sensory inputs from the body flow. When cells in the thalamus detect something that requires urgent attention from the rest of the brain, they begin “bursting” — many cells firing off simultaneous signals to get the attention of the cortex. Once the threat passes, the cells quickly switch back to quieter activity.
Using optogenetics and other technology, researchers have for the first time precisely manipulated this bursting activity of the thalamus, tying it to the sense of touch. The work, done in animal models, was reported in the journal Cell Reports and sponsored by the National Institutes of Health’s National Institute of Neurological Disorders and Stroke.
“If you clap your hands once, that’s loud,” explained Garrett Stanley, a professor in the Wallace H. Coulter Department of Biomedical Engineering at Georgia Tech and Emory University. “But if you clap your hands several times in a row, that’s louder. And if you and your friends all clap together and at the same time, that’s even stronger. That is what these cells do, and the idea is that this mechanism produces bursts synchronized across many cells to send out a very strong signal about a stimulus in the outside world.”
Neuroscientists have long believed that such coordinated spikes of activity serve to focus the brain’s attention on issues requiring immediate attention. Stanley and graduate student Clarissa Whitmire — working with researchers Cornelius Schwarz and Christian Waiblinger from the University of Tübingen in Germany — used optogenetics techniques to study bursting activity in the thalamus regions of rats. — John Toon