Neurology Central

Study of brain activity demonstrates how neurons control muscle movement in paralyzed ALS patients

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A team of researchers from Stanford University (CA, USA) have built on previous animal studies to report how individual neurons control muscle movement in human patients suffering from paralysis as a result of amyotrophic lateral sclerosis (ALS). The findings – published recently in eLife – could assist in the development of improved brain-controlled prosthetic devices.

The two individuals diagnosed with ALS who participated in the study were a 51-year-old female who had retained some movement in her wrists and fingers, and a 54-year-old man who had retained slight movement in one of his index fingers.

The study builds on previous preclinical research from Stanford, which reported how motor cortical neurons work as part of an interconnected circuit to create rhythmic patterns of neural activity, which in turn drive muscle contractions.

Joint senior author Krishna Shenoy from Stanford University explained: “What we discovered in our preclinical work is evidence of how groups of neurons coordinate and cooperate with each other in a very particular way that gives us deeper insight into how the brain is controlling the arm.”

The two participants involved in the current study had electrode arrays implanted in their brains’ motor cortex as part of the BrainGate 2 trial, which investigates the efficacy of a neural interface system in individuals with tetraplegia in controlling a computer cursor and other assistive devices with their thoughts.

These implanted arrays enabled researchers to record electrical brain activity from individual neurons as the patients completed tasks, such as attempting to move their fingers and wrists, which were equipped with sensors to measure movement. In general, this type of mapping in humans can only be performed during brain surgery.

The results demonstrated that the neurons in the ALS patients functioned in a similar way to those investigated in the preclinical studies – through utilizing similar rotational patterns – which commenced when the participant initially thought about moving.

Going forward, the research team plan to utilize their data in order to help improve algorithms that translate neural activity (in the form of electrical impulses) into control signals. It is these signals that enable a robotic arm or computer cursor to be guided.

Senior coauthor Jaimie Henderson from Stanford University added: “We hope to apply these findings to create prosthetic devices, such as robotic arms, that better understand and respond to a person’s thoughts.”

Future studies in individuals without ALS are also needed to confirm whether the patterns reported in this study weren’t specific to ALS.

Sources: Pandarinath C, Gilja V, Blabe CH et al. Neural population dynamics in human motor cortex during movements in people with ALS. eLife, 2015; 4:e07436, DOI: http://dx.doi.org/10.7554/eLife.07436; Stanford Medicine press release

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