The spinal cord acts as a control wire, connecting the brain to the rest of the body. If it is cut, people lose the ability to move their bodies below the point of damage. However, if it is just partially severed, the brain can occasionally adapt to the injury. Some persons who are paralyzed due to a spinal cord injury can eventually regain some capacity to walk.
It’s unclear which parts of the brain are involved in this adaptation. However, in a recent publication published in Nature Medicine, a team of researchers led by Jocelyne Bloch of Lausanne University Hospital and Grégoire Courtine of the Swiss Federal Institute of Technology in Lausanne gave some clarity. In doing so, they demonstrate that stimulating the proper areas of the brain can result in dramatic—and seemingly permanent—improvements in patients’ ability to walk again.
The researchers identified a collection of neurons in the lateral hypothalamus (LH; a portion of the brain buried deep towards the bottom of the organ) as the most likely culprit. According to the research team, this was unexpected because the LH is well recognized for its involvement in appetite, thirst, and other involuntary nervous system processes.
To ensure they were on the correct road, the researchers used optogenetics. This includes altering live cells to express light-sensitive proteins known as channelrhodopsins. These function as switches, enabling cellular activity to be regulated by bursts of light. Indeed, increasing the activity of neurons in the LH enhanced damaged animals’ capacity to walk. In other situations, it even caused the mice to jump.
Optogenetics is not typically authorized for usage in humans. Deep-brain stimulation (DBS) is an alternate approach for stimulating neurons. Rather than altering cells to respond to light, this method involves introducing small electrodes into the brain and activating neurons with electrical currents. Switching to DBS necessitated a second round of testing, this time with rats.
The final stage was to test it on individuals. The researchers selected two volunteers who had sustained spinal injuries and subsequently relearned how to walk with help. The electrodes were placed while they were conscious. This helped the surgeons know they were in the appropriate area, as both patients reported a desire to move when the current was turned on.
After three months of therapy, both reported significant gains in walking, as measured by distance traveled in a given time and perceived difficulty. Before the procedure, one of them intended to walk without braces, and the other to ascend and descend a staircase independently. Both attained their objectives.
Source: Economist
