SNHS Spotlight: Neuroprosthetics

I had the opportunity to take a class in the summer of 2019 held at Yale University taught by Andrew Savoy, a doctoral student in Integrative Neuroscience at the University of Chicago. I learned about various systems in the brain and applied what we learned to fictitious neurological patients. Specific focus was put on the cerebral cortex, various subcortical structures, the visual system, the somatosensory system, and the motor system in the brain and spinal cord. At the conclusion of the program, each student had to research and present a final project to the group. My project was on neuroprosthetics and how they are connected to the brain.

The motor cortex is a part of the brain and its function is to produce movement and behaviors. Action for any given moment is done in the frontal lobe and then it issues its request to the motor cortex. The motor cortex then decides which muscle it is going to contract. The motor tract starts in the motor cortex and then goes down within the brain and to the other side of the spine to the body part that it is going to control. 

An electrode array in the brain, credit to Johns Hopkins University.

There are two parts of prosthetics, the electrodes and the mechanical limb. Electrodes are solid conductors that carry an electrical current and the mechanical limb is the actual prosthetic. 

The function of the prosthetic part is to translate the brain’s electrical activity via computer algorithms and then turn the thought into motion. So say you want to move your arm to grab a glass of water, the brain will send a signal down to the prosthetic limb so you can actually grab the glass. The brain activity produced by the thought was processed through the computer and controls the limb. The electrodes are connected to the mechanical limb. The electrode rays are placed in the brain nerves or muscle to decode the message between the brain and the limb that controls movement. The goal is to put the electrodes in the motor cortex so that when a patient imagines moving their limb there is a characteristic pattern of activation in the motor part of their brain. Scientists can take the signal from the motor cortex and infer what the pattern wants to do and therefore the prosthetic limb will do that action. 

There is a great deal of research currently underway in this area. For example, researchers at Texas A&M, the University of North Carolina, and the University of Florida are collaborating to study prosthetics that use an electromyography-based human-machine interface. This method records electrical activity in muscles that generate signals that trigger the interface which then translates them into a unique pattern of commands. These commands then allow the patient to move their prosthetic limb. Testing of prototypes will allow researchers to provide feedback and guidance to the engineers who create these interfaces, which will lead to better prosthetics for amputees as well as other technological advances. 

By: Rania Hart’22, SNHS member

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