When people are drowning or choking they are unable to breathe and not enough oxygen gets in their body. Similarly, when one suffers a stroke there is not enough oxygenated blood going to the brain; this can result in severe damage to the brain and in many cases loss of motor function and paralysis. The brain makes connections with the human body similar to wires in electrical circuits, current flows from one direction to the other and the other way around. However, if you damage the circuit, the information doesn’t get communicated. In the body, information is communicated via neuronal fibers which are compromised after a stroke. Recovering from strokes and regaining the lost motor function is an uphill fight. There are many different strategies to improve motor function, such as rehabilitative training, electrical stimulation, drugs/medication; but what is best, what method will almost completely return what was lost? 

Researchers and scientists set out to find a solution by experimenting with adult rats. The scientists caused strokes in the animals by inducing the blockage of blood vessels which resulted in 90% damage to the motor cortex (a region responsible for controlling motor execution) in the brain. The animals were then tested for improvement in their forelimb function after being treated with different therapy and rehabilitation schedules. Forelimb function was tested by the rat’s ability to reach for food pellets. It was found that the rats which were given a nerve growth-promoting antibody followed by extensive rehabilitative training showed the best results. They were also able to perform other novel forelimb tasks using their regained skill. In contrast, rats who were simultaneously given the antibody treatment and rehabilitative training showed results that were functionally much worse. This showed that timing was an important factor for success since the stroke damaged circuit needed time to regrow before being reinforced by training.  

To further investigate how this circuit was redeveloped the scientists conducted another experiment by labeling the intact corticospinal tract (neuronal fibers which start in the brain/motor cortex that go into the spinal cord to be able to control voluntary movements). In the group in which rats were given rehabilitative training later, it was found that the nerve fibers from the intact motor cortex and corticospinal tract crossed the midline of the spinal cord to the opposite side which was denervated due to the stroke. These “crossed” neuronal fibers formed organized connections with motor regions of the spinal cord which had lost its input from the motor cortex. However, in the group of rats who were simultaneously given the antibody treatment with rehabilitative training, the connections formed by the nerve fibers were less organized and had an abnormal growth pattern such as excess sprouting and incorrect formation of circuits. The results suggested that sequential treatment was most effective. First, the antibody treatment increased the plasticity potential of the brain and spinal cord, or in other words, it increased the chances of these structures to undergo biological changes. Next, the use of rehabilitative training led to the selection and enforcement of the functionally significant connections formed by the neuronal fibers. 

The scientists, to further prove that these crossing midline neuronal fibers had functional relevance, performed additional experiments in which they delivered a virus and a drug that blocked these fibers. When the rats were retested in their forelimb function, they saw a rapid decline in motor ability. These results supported the initial hypothesis that the growth of the nerve fibers and then the re-established connections with the stroke impacted areas were essential to the functional restoration. 

Although, it is still unclear if these methods could be used for other conditions in which paralysis is common such as Cerebral palsy, Guillain-Barré syndrome, and Peripheral neuropathy. Neuronal degeneration can also cause many other types of conditions and diseases in the body like Parkinson’s and Alzheimer's disease. It would be interesting to see in what other ways, specifically, the antibody nerve growth treatment could be adjusted and used for these other purposes.  

According to the World Health Organization, 15 million people suffer strokes worldwide each year; of those 15 million, 5 million are severely disabled. The research done by these scientists found that giving an antibody treatment inducing nerve growth, followed by extensive rehabilitative training leads to high levels of functional restoration in comparison to conventional rehabilitative medicine. This new method to treat post-stroke paralysis provides hope for those 5 million people who suffered an unlucky fate. The research done may seem like a small step in science but even the smallest of steps can be a leap for mankind. 

Other text sources

Asynchronous therapy restores motor control by rewiring of the rat corticospinal tract after stroke. (n.d.). Retrieved from science-sciencemag-org.ezp-prod1.hul.harvard.edu/content/344/6189/1250.long

Neurodegenerative Diseases . (2020, July 14). Retrieved from medlineplus.gov/degenerativenervediseases.html

The Internet Stroke Center. (n.d.). Retrieved from strokecenter.org/patients/about-stroke/stroke-statistics/