(MEMPHIS, Tenn. – November 13, 2026) Our brains are constantly computing how to move and coordinate different parts of our body, but exactly how this orchestration is represented in the brain has been challenging to untangle. Now, scientists at St. Jude Children's Research Hospital and Columbia University have used high-speed optical brain imaging to uncover a previously unknown map within the mouse secondary motor cortex, revealing distinct regions associated with different parts of the body. This discovery offers new insights into how the brain organizes and coordinates movements and could help researchers understand how these processes are disrupted by neurological disease or brain injury. The findings were published today in Nature Communications.
"Finding this map was unexpected," said corresponding author Elizabeth Hillman , PhD, St. Jude Department of Imaging Sciences chair. "We were initially looking for the primary brain regions that drive movement, but we noticed that during periods of rest, sensory areas had strong fluctuations in brain activity. Each sensory area's resting activity was synchronized with a small area of secondary motor cortex (M2). When we fitted all the M2 regions together, they formed a neat little body-part map."
The researchers then examined neuronal activity within these subregions, confirming that activation depended on which body part was in use. By comparing activity patterns for different kinds of movements, they saw that secondary motor cortex activates more strongly during complicated, coordinated movements involving multiple body parts.
"All of these features explain why it has been so difficult to interpret motor cortex activity patterns during movements," Hillman explained, "Secondary motor cortex activity shifts between different states: from synchronized fluctuations during rest, to engaging transiently for simple movements, and sustaining during more complex movements involving multiple body parts. Once we figured out the pattern, activity became much easier to interpret. It was like recognizing which instruments were playing in the orchestra."
Optical mapping provides holistic view of movement-related brain activity
Hillman has pioneered the wide-field optical mapping approach used in this study to produce real-time readouts of neural activity across the brain during spontaneous movements. "Until recently, studies in neuroscience have averaged together multiple repetitions of the same movement or stimulation, often while focusing on a small region of the brain," Hillman explained. "By continuously imaging activity across the brain, we discovered that these regions fluctuated together when at rest and became quiet when movement begins. Analyzing these patterns revealed communication pathways between multiple regions that earlier imaging approaches had hidden."
Hillman is excited about the potential of her high-speed imaging approaches to unlock more secrets of the brain, including how diseases affect the way that the brain functions. "This study demonstrates that we can visualize how the brain controls movements in real-time, so we can also analyze how and when that system fails," Hillman said. She hopes to leverage this approach to explore disease mechanisms and biomarkers and evaluate therapies for a range of pediatric conditions that affect movement, behavior and cognition.
Authors and funding
The study's first author is Weihao Xu, Columbia University. The study's other authors are David Thibodeaux, Kosisochukwu Ugorji, Somayeh Shahsavarani, Sharon Kim, Fatema Lodgher, Hanzhi Zhao, Elizabeth Malan, Kaitlyn Swayze and Morgan Cambareri, Columbia University; Lina Marcela Carmona, Columbia University and University of Massachusetts Chan Medical School; and Wenze Li, Lu Xu, Caitlin Freeman and Anupam Bisht, St. Jude.
The study was supported by the National Institute of Neurological Disorders and Stroke BRAIN Initiative (U19NS104649, R01NS076628, R01NS063226 and UM1NS132358), the National Institute of Mental Health BRAIN Initiative (RF1MH114276 and RF1MH128969), the Simons Collaboration on the Global Brain (542991), the Leducq Foundation (22CVD01)and the American Lebanese Syrian Associated Charities (ALSAC), the fundraising and awareness organization of St. Jude.
