New research from Stanford University sheds light on how neurons control muscle movement. The findings could be applied to create better brain-controlled prosthetic devices, such as robotic arms.
The Stanford engineers have found that groups of neurons work together, firing in complex rhythms to signal muscles about when and where to move.
In a 2012 Nature paper, however, Krishna Shenoy, professor of electrical engineering, and his colleagues reported finding that animals' motor cortical neurons work as part of an interconnected circuit to create rhythmic patterns of neural activity.
To understand whether neurons fire similarly in humans, the researchers recorded motor cortical brain activity of two research participants with the degenerative neurological condition called amyotrophic lateral sclerosis, or ALS. The condition, which also is known as Lou Gehrig’s disease, damages neurons and causes patients to lose control over their muscles.
The participants, a 51-year-old woman who retained some movement in her fingers and wrists, and a 54-year-old man who could still move one of his index fingers slightly, are participants in the BrainGate2 trial, which is testing a neural interface system that allows thoughts to control computer cursors, robotic arms, and other assistive devices.
For the trial, electrode arrays were implanted in the brains of the patients' motor cortex. The researchers were then able to record electrical brain activity from individual neurons while the participants moved or tried to move their fingers and wrists, which were equipped with sensors to record physical movement.
The researchers found that the ALS patients’ neurons worked very similarly to the pre-clinical research findings. The Stanford team now plans to use their data to improve the algorithms that translate neural activity in the form of electrical impulses into control signals that can guide a robotic arm or a computer cursor.
