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Research Findings Show Potential New Target in Somatosensory Cortex to Aid in Recovery of Walking Ability

Milwaukee, Nov. 18, 2019 – Findings of a study published today in the journal Nature Neuroscience show the brain’s somatosensory cortex can directly orchestrate walking in response to ongoing environmental cues, allowing for navigation of complex environments. Kajana Satkunendrarajah, PhD, Assistant Professor of Neurosurgery and Physiology at the Medical College of Wisconsin (MCW), led the study with Spyridon Karadimas, MD, PhD, of the University of Toronto. The study was conducted in the laboratory of Michael Fehling, MD, PhD, a Senior Scientist at the Krembil Research Institute in Canada.

Locomotion is critical for survival in both humans and animals. The way we walk is shaped by neuronal circuits in the spinal cord. However, when and how we walk based on sensory information, emotions and motivation is governed by neural circuits in the brain and brainstem. This study sheds light on if and how the sensory cortex, possessing instantaneous and ongoing information about the body’s internal and external status, directs the spinal circuitry.

The researchers found that neurons in the sensory cortex are active before and during the movement and that this activity is strongly correlated with the speed of walking. Using cutting-edge technology, they found that these sensory cortical signals can bypass any other movement center in the brain and directly reach and influence the spinal cord to efficiently modulate walking.

Surprisingly, when the sensory cortical neurons that are connected to the spinal cord are inactivated, mice lose their ability to maintain walking, while the same mice walked more efficiently and faster when this newly discovered pathway was stimulated.

This newfound discovery in the healthy central nervous system will contribute to a greater understanding of how recovery of walking can be promoted in patients who have suffered from a serious injury that impaired their ability to walk.

“Currently, there are no promising treatment strategies to promote walking after damage to the brain and spinal cord,” Dr. Satkunendrarajah said. “Part of the problem is that there are many unanswered questions regarding the neural control of locomotion in both healthy and pathological conditions. Our identification of this sensory cortical pathway in the control of walking provides new neural substrates that we can manipulate to promote recovery of walking after injury.”

What remains unknown is how the sensory cortex encodes information about the future status of movement. Dr. Satkunendrarajah’s future work will focus on dissecting the input-output architecture of sensory cortical neurons of this pathway.

At MCW, Dr. Satkunendrarajah’s research program focuses on how the brain processes complex information and interacts with the outside world by generating movement. Her research on motor control and spinal cord injury combines fundamental neuroscience, respiratory and locomotor physiology, as well as preclinical neural circuit manipulation using cutting-edge viral techniques, optogenetics, pharmacogenetics and electrophysiology in transgenic mice. The ultimate goal of her research is to discover new neural targets for the treatment of central nervous system diseases such as stroke and traumatic brain and spinal cord injury.

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