Brain Imaging Shows Action-Based Brain Organization in Individuals Without Hands

Recent brain imaging studies have challenged long-held beliefs about how the brain organizes motor functions. Traditionally, it was thought that specific regions of the brain control individual body parts, such as the hands or feet. However, new research from Georgetown University suggests that the brain may instead be organized primarily around types of actions, like reaching or tool use, regardless of which body part performs them.

In a study published in the Proceedings of the National Academy of Sciences, neuroscientists examined individuals born without hands who utilize their feet to perform daily tasks, including those with tools. Using functional MRI scans, the researchers observed that brain areas typically associated with hand and tool control remain active when these individuals use their feet. This indicates that the brain’s organization might focus on action types rather than body parts.

Lead researcher Ella Striem-Amit explained that some regions of the brain prioritize the nature of the action over the anatomical body part involved. This flexibility may allow the brain to adapt and compensate for limb loss, which has significant implications for rehabilitation strategies following brain injuries. Interestingly, certain areas like the primary motor cortex, which are usually tightly mapped to specific body parts, did not show significant reorganization even in individuals who used their feet for tool-related activities, highlighting different degrees of plasticity across brain regions.

The findings point toward a more abstract and action-centered model of brain organization. This model demonstrates that the brain can develop functional maps based on action types, even without traditional motor experience, and aligns with prior research on neural plasticity in sensory deprivation such as blindness or deafness.

One notable participant, Alvin Law, who was born without arms due to a birth defect, emphasized the importance of understanding brain plasticity. He uses his legs and feet for daily activities and recognizes that insights from this research could enhance assistive technologies for limb loss. Overall, this study broadens our understanding of how the brain adapts and organizes motor functions, revealing a remarkable capacity for flexibility that could reshape rehabilitation approaches.

Source: https://medicalxpress.com/news/2025-08-brain-scans-reveal-action-based.html