Newswise — Québec City, April 19, 2023 -
Individuals who have experienced a spinal cord injury resulting in the loss of leg control may have the opportunity to walk again in the future. A team of researchers associated with the Université Laval and the CHU de Québec-Université Laval Research Center have identified a fresh neurological focal point that may enhance gait recuperation.
Despite common belief, spinal cord injuries are infrequently total. The brain preserves access to the spinal cord circuitry situated beneath the injury, but this linkage is typically inactive. Electric stimulation or deep brain stimulation could stimulate it and encourage the revitalization of locomotion. However, which region of the brain should be the target?
Frédéric Bretzner, a professor at Université Laval’s Faculty of Medicine, has led a group of researchers who have directed their attention towards the mesencephalic locomotor region, a center for locomotion in the brain. This particular area has been recognized as a catalyst for walking in various animal species. It comprises the cuneiform nucleus and the pedunculopontine nucleus. While deep brain stimulation of the pedunculopontine nucleus has produced mixed outcomes in Parkinson's patients with gait and postural issues, no clinical research has been conducted on the cuneiform nucleus.
A Promising Area of the Brain
By employing optogenetics, Professor Frédéric Bretzner's research group altered neurons to render them sensitive to light. They subsequently utilized blue light to stimulate glutamatergic or excitatory neurons in the cuneiform or pedunculopontine nucleus in mice.
Frédéric Bretzner explains that following spinal cord injury, activating excitatory neurons in the cuneiform nucleus via stimulation was able to initiate walking in resting mice. Additionally, during a naturally occurring walking episode, stimulation improved the coordination between the hind leg muscles and the quality of the mouse's walk.
In contrast, the activation of glutamatergic neurons in the pedunculopontine nucleus rarely induced walking in resting mice. On the contrary, stimulation caused the mice to halt their walking.
Professor Bretzner reports that based on their findings, it appears that the cuneiform nucleus would be a more effective neurological target than the pedunculopontine nucleus to enhance walking recovery in individuals who have experienced a spinal cord injury.
As the development of implants and optogenetic tools designed to target glutamatergic neurons of the cuneiform nucleus in humans is still underway, electrical stimulation of the cuneiform nucleus could already enhance walking recovery in individuals who have suffered a spinal cord injury.
Implementing this approach could also enhance the quality of life for individuals who are afflicted with traumas or neurodegenerative conditions that impact gait and posture, such as Parkinson's disease, amyotrophic lateral sclerosis, or stroke.
The study was recently published in the scientific journal Cell Reports Medicine, and the authors of the study are Marie Roussel, David Lafrance-Zoubga, Nicolas Josset, Maxime Lemieux, and Frederic Bretzner, all of whom are affiliated with Université Laval.
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