Continuing research by Krishna Shenoy, PhD, a professor in the Electrical Engineering, Neurobiology (by courtesy), and Bioengineering (affiliate) Departments at Stanford University, California, has revealed more about how the brain controls arm movements. Specifically, how the neurons in the brain control planned versus unplanned arm movements. “In addition to advancing basic brain science, these new findings will lead to better brain-controlled prosthetic arms and communication systems for people with paralysis,” Shenoy said.
In a paper published online January 24 in the journal Neuron, Shenoy and first author Katherine Cora Ames, a doctoral student in the Neurosciences Graduate Program, presented a mathematical analysis of the brain activity of monkeys as they make anticipated and unanticipated reaching motions.
The experimental data came from recording the electrical activity of neurons in the brain that control motor and premotor functions. The idea was to observe and understand the activity levels of these neurons during experiments in which the monkeys made planned or reactive arm movements. What the researchers found is that when the monkeys knew what arm movement they were supposed to make and were simply waiting for the cue to act, electrical readings showed that the neurons went into what scientists call the prepare-and-hold state-the brain’s equivalent of ready, set, waiting for the cue to go. But when the monkeys made unplanned or unexpected movements, the neurons did not go through the expected prepare-and-hold state. Before the experiment, the researchers had believed that a prepare-and-hold state had to precede movement. In short, they thought the neurons had to go into a “ready, set” crouch before acting on the “go” command. In these instances, the neurons just said, “Go!”
These nuanced understandings are important to Shenoy. His lab develops and improves electronic systems that can convert neural activity into electronic signals in order to control a prosthetic arm or move the cursor on a computer screen. One example of such efforts is the BrainGate clinical trial at Stanford, now being conducted under U.S. Food and Drug Administration supervision, to test the safety of brain-controlled, computer cursor systems-“think-and-click” communication for people who can’t move.
Editor’s note: For more information, read “Stanford Joins BrainGate Team Developing BCIs” and “Stanford Researchers Advance the Performance of BCIs.” This story was adapted from materials provided by Stanford University.
