A new model for understanding how nerve cells in the brain control movement may help unlock the secrets of the motor cortex, a critical region that has long resisted scientists' efforts to understand it, researchers report June 3 in Nature.
Scientists at Washington University in St. Louis, Stanford University and Columbia University have shown that the motor cortex's effects on movement can be much more easily understood by looking at groups of motor cortex neurons instead of individual nerve cells. In the study, scientists identified rhythmic brain cell firing patterns coordinated across populations of neurons in the motor cortex. They linked those patterns to different kinds of shoulder muscle movements.
"Populations of neurons in the motor cortex oscillate in beautiful, coordinated ways," says co-first author John Cunningham, PhD, assistant professor of biomedical engineering at Washington University in St. Louis. "These patterns advance our understanding of the brain's control of movement, which is critical for understanding disorders that affect movement and for creating therapies that can restore movement."
Until now, scientists had based their studies of the motor cortex on decades-old insights into the workings of the visual cortex. In this region, orientation, brightness and other characteristics of objects in the visual field are encoded by individual nerve cells.
However, researchers could not detect a similar direct encoding of components of movement in individual nerve cells of the motor cortex.
"We just couldn't look at an arm movement and use that to reliably predict what individual neurons in the motor cortex had been doing to produce that movement," Cunningham says.
For the new study, conducted at Stanford University, scientists monitored motor cortex activity as primates reached for a target in different ways. They showed that the motor cortex generated patterns of rhythmic nerve ce
|Contact: Michael C. Purdy|
Washington University School of Medicine