A Step in a New Direction

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New Krembil study changes our understanding of how the brain directs the body to walk.
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Adult Canadians each take an average of nearly 9,000 steps every day. Although walking does not require our full attention, our brains must still signal each step.

Dr. Michael Fehlings, a Senior Scientist at the Krembil Research Institute, and his research team have discovered a network of nerve cells that plays a key role in controlling our ability to walk. The group’s findings, published in Nature Neuroscience, challenge conventional perceptions of how the brain instructs and regulates the body while walking.

Although walking may seem like an innate and straightforward action, it takes many complex processes and different regions of the brain to effect the movements involved. A full understanding of how we walk still eludes researchers.

The prevailing view has been that the motor cortex, a region of the brain that controls the planning and initiation of limb movements, directs the body to walk.

The study, led by Dr. Fehlings’ former trainees Drs. Spyridon Karadimas and Kajana Satkunendrarajah, revealed that a different region of the brain, the sensory cortex, can also generate commands that trigger walking. This is surprising because the sensory cortex’s main function is to process information on the internal and external environments of the body. For example, the sensation of warm sunlight on your skin is processed by the sensory cortex.

The researchers further found that the sensory cortex sends these commands directly to the spinal cord through a relay of nerve cells. This relay is distinct from and operates in parallel with the signalling route of the motor cortex.

“Our data support a potential mechanism through which the sensory cortex can directly and efficiently control walking in response to the sensory information that is continuously processing,” says Dr. Fehlings.

Future research will delve into the mechanisms that govern the generation of signals in the sensory cortex to deepen our understanding of how we walk.

This work was supported by the Krembil Foundation, the Canadian Institutes of Health Research, AOSpine, the Halbert Chair, the DeZwirek Foundation, the Onassis Foundation and the Toronto General & Western Hospital Foundation.  

Karadimas SK, Satkunendrarajah K, Laliberte AM, Ringuette D, Weisspapir I, Li L, Gosgnach S, Fehlings MG. Sensory cortical control of movement. Nat. Neurosci. 2019 Nov 18. doi: 10.1038/s41593-019-0536-7.

Dr. Michael Fehlings, Senior Scientist, Krembil Research Institute.

Dr. Kajana Satkunendrarajah (left) is now an Assistant Professor at the Medical College of Wisconsin, and Dr. Spyridon Karadimas (right) is a neurosurgery resident at the University of Toronto.