Deep Brain Stimulation Improves Paralyzed Rat's Gait

Electrically stimulating a key region deep in the brain improves locomotion in rats with spinal cord injuries

2 min read
Deep Brain Stimulation Improves Paralyzed Rat's Gait
Photo: iStockphoto

Swiss researchers have enabled rats with severe spinal cord injuries to walk and swim by electrically stimulating a group of neurons located deep in the brain. The discovery may give researchers a new approach to treating severe spinal cord injury. The research, led by Lukas Bachmann at the Brain Research Institute at the University of Zurich, was published today in Science Translational Medicine.

In most spinal cord injuries, some nerve fibers connecting the brain to the spinal cord below the injury site remain intact, even in severe cases in which a person is paralyzed. Bachmann and his colleagues found that by stimulating a key region of the midbrain called the mesencephalic locomotor region, or MLR, the remaining intact nerve fibers could be recruited to improve walking and swimming movements in spinal-cord injured rats.

The scientists used a technique called deep brain stimulation. Electrodes implanted in the rats' midbrains sent 50 hertz cathodal pulses into their MLR regions. The extent to which the stimulation improved the rats' gait varied depending on the severity of the spinal cord injury. Rats who had lost 70 to 80 percent of their reticulospinal fibers were severely impaired, but not paralyzed—comparable to a human who can walk but has major deficits in strength and speed. Deep brain stimulation gave these rats a close-to-normal gait.

Rats that had lost more than 90 percent of their fibers were almost fully paralyzed in the hindlimbs—comparable to a human who is wheelchair-bound. Deep brain stimulation enabled these rats to move their hindlimbs while swimming.

It has been known for decades that the MLR orchestrates the parts of the brainstem that control walking. Recently scientists have used deep brain stimulation of this region to treat patients suffering from disorders such as Parkinson's disease. The new Swiss research suggests that this type of stimulation may also help people with spinal cord injuries. "I believe we have delivered the first promising indications that may help us in finding possible treatments for spinal cord injury," says Bachmann. "But much still remains to be investigated."

Bachmann says his research also provides the first indications of which parts of the brainstem may be responsible for conveying different components of walking during deep brain stimulation. "We think that areas closer to the midline in the brainstem do convey the rhythmic components of walking whereas areas more on the side convey the strength aspects of the MLR stimulation effect," Bachmann says.

Scientists have been experimenting with electrical stimulation of other parts of the central nervous system for many years in both animals and humans. In one recent and promising approach, researchers at the University of Louisville used epidural stimulation to enable a paralyzed man to stand on his own. The researchers used a 16-electrode array to stimulate the man's spinal cord below the site of his injury, essentially cutting the brain out of the equation. For more on that story, stay tuned for a feature we will post tomorrow. 

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This CAD Program Can Design New Organisms

Genetic engineers have a powerful new tool to write and edit DNA code

11 min read
A photo showing machinery in a lab

Foundries such as the Edinburgh Genome Foundry assemble fragments of synthetic DNA and send them to labs for testing in cells.

Edinburgh Genome Foundry, University of Edinburgh

In the next decade, medical science may finally advance cures for some of the most complex diseases that plague humanity. Many diseases are caused by mutations in the human genome, which can either be inherited from our parents (such as in cystic fibrosis), or acquired during life, such as most types of cancer. For some of these conditions, medical researchers have identified the exact mutations that lead to disease; but in many more, they're still seeking answers. And without understanding the cause of a problem, it's pretty tough to find a cure.

We believe that a key enabling technology in this quest is a computer-aided design (CAD) program for genome editing, which our organization is launching this week at the Genome Project-write (GP-write) conference.

With this CAD program, medical researchers will be able to quickly design hundreds of different genomes with any combination of mutations and send the genetic code to a company that manufactures strings of DNA. Those fragments of synthesized DNA can then be sent to a foundry for assembly, and finally to a lab where the designed genomes can be tested in cells. Based on how the cells grow, researchers can use the CAD program to iterate with a new batch of redesigned genomes, sharing data for collaborative efforts. Enabling fast redesign of thousands of variants can only be achieved through automation; at that scale, researchers just might identify the combinations of mutations that are causing genetic diseases. This is the first critical R&D step toward finding cures.

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