Researchers Uncover Brainstem Pathway Key to Hand Control

Study reveals unexpected neural network linking brainstem, spinal cord, and cortex for voluntary hand movements.

Mar. 13, 2026 at 5:36am

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Researchers have identified a network of connections linking the brainstem and spinal cord that helps control hand and arm movements, revealing an unexpected layer of the nervous system enabling people to grasp, hold, and manipulate objects. The study, led by researchers at UC Riverside, used brain imaging in both mice and humans to map this pathway, which could help guide new therapies aimed at restoring hand and arm function after stroke or other neurological injuries.

Why it matters

For a long time, it was thought that fine hand movements in humans were controlled almost entirely by the brain's outer cortex. This research shows that evolutionarily older brainstem structures also play an important role in voluntary hand control, providing new insights into the complex neural networks underlying dexterous movement.

The details

The researchers observed activity in two regions of the medulla, the lowest portion of the brainstem that sits just above the spinal cord and helps regulate essential processes. Using functional MRI, they found that these medulla regions were consistently active during controlled hand movement tasks in both mice and humans, and were strongly connected with sensorimotor areas of the brain. The study also showed that two segments of the spinal cord in the neck, cervical levels C3 and C4, help control the hand by acting as a relay between the brainstem and the lower spinal cord that directly activates hand muscles.

  • The research was published in the Proceedings of the National Academy of Sciences in March 2026.

The players

Shahab Vahdat

An assistant professor of bioengineering at UC Riverside who led the study.

UC Riverside

The university where the research was conducted.

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What they’re saying

“For a long time, we thought fine hand movements in humans were controlled almost entirely by the cortex. What we are observing is that evolutionarily older brainstem structures also play an important role.”

— Shahab Vahdat, Assistant Professor of Bioengineering

What’s next

The researchers say the work could help guide new therapies aimed at restoring hand and arm function after stroke or other neurological injuries by providing additional targets to explore for neuromodulation treatments.

The takeaway

This study challenges the long-held view that voluntary hand movements are controlled solely by the brain's outer cortex, revealing an unexpected neural network involving the brainstem and spinal cord that is critical for dexterous hand control. These findings could lead to new approaches to rehabilitation and restoration of hand function after neurological damage.