BCIwiki (bciwiki.com) — Neurons in the motor cortex of people using intracortical brain-computer interfaces (BCIs) grew more active the more human-like an observed effector looked, researchers from Brown University, Mass General Brigham, the Veterans Affairs Providence Healthcare System and Harvard Medical School reported in Proceedings of the National Academy of Sciences of the United States of America (PNAS) on September 21, 2026, according to the abstract indexed on PubMed.
Motor cortex neurons are known to engage not only during movement but also while watching humans or monkeys move. How they respond when people watch the assistive or prosthetic devices that intracortical BCI users control had not been established.
The team recorded single-unit activity in the precentral gyrus while BCI users viewed grasp-like movements performed by a spectrum of virtual effectors, ranging from human hands to robotic hands and hand-like dot stimuli. Neural modulation tracked effector anthropomorphicity, or human-likeness, both across the neural ensemble and within individual neurons, which the authors say suggests human motor cortex activity rises incrementally with the observed agent's human-likeness. Solicited and spontaneous feedback from the participant also linked neural activity to subjective judgments of human-likeness, pointing to a strong role for context in observation-induced activity.
During attempted hand movements, however, motor cortex activity remained similar regardless of which effector was on screen. The authors suggest that intuitive control of external devices through intracortical BCIs may not be overtly affected by how human the effector appears. The abstract does not report the number of participants or the implanted device used.