The Brain Can Rewire Itself After an Injury
Researchers are trying to grasp natural regeneration process, learn to help it do its job
Excerpted from San Diego Union Tribune | By Bradley J. Fikes
April 2, 2015
Living things can repair themselves. Damaged skin and fractured bones heal, and a damaged liver can regenerate itself.
Only recently have scientists begun to understand this is also true of the brain.
Perpetually responding to its environment, the brain possesses a remarkable ability to rewire itself, to actually reroute sensory impulses and change its physical structure.
Brain injuries, whether internally caused by a stroke or externally by some type of trauma, represent the supreme test of this regenerative ability.
Stroke is the third-leading cause of death in the United States, killing nearly 130,000 Americans annually, according to the U.S. Centers for Disease Control and Prevention. A total of 795,000 people have a stroke annually. Most of these strokes are ischemic — that is, caused by an interruption in oxygen supply to a part of the brain. Blood clots commonly cause ischemic strokes.
Meanwhile, brain trauma caused more than 50,000 deaths in the U.S. in 2010, according to the CDC. And traumatic brain injury was diagnosed in more than 280,000 hospitalization cases.
In children, falls caused 55 percent of such injuries. The rate soars to 81 percent in adults older than 65. Among all ages, motor vehicle crashes caused 14 percent of cases. And with the wars in Iraq and Afghanistan, thousands of American troops have endured such injuries.
Whether caused by stroke or external trauma, these brain injuries present much of the same challenges in rehabilitation, said Dr. Michael Lobatz, a neurologist with the La Jolla-based Scripps Health network. Undamaged parts of the brain need to learn how to take over functions normally performed by the portions that have been harmed.
“There are a number of things that occur in the brain as a person either spontaneously recovers or is in the process of doing rehabilitation,” Lobatz said. “Number 1, you get new connections growing from one part of the brain to the other to fill that void. Two, when people go to therapy, they strengthen what is weak and adapt to those things that cannot be changed.”
The old, fatalistic concept of brain damage was that while a patient can adapt, the brain cannot repair itself, Lobatz said. But researchers including Fred “Rusty” Gage at the Salk Institute for Biological Studies in La Jolla demonstrated that neurogenesis — the growth of new neurons — takes place in the adult human brain. Gage and some colleagues reported in 1999 that new neurons are formed in the brains of adults at least up to 72 years of age.
Researchers are seeking to assist this regeneration in multiple ways, such as by:
Retraining the brain through physical and cognitive therapy to perform various functions by using undamaged area
Replacing lost abilities with prosthetics that assist in hearing, sight and movement
Repairing damage through stem cells and other cellular therapy.
All of these avenues are being researched in San Diego, Lobatz said.
Now, the field is shifting toward the use of robotics to retrain and strengthen new connections for moving paralyzed or partially paralyzed limbs.
Physical therapists typically assist patients with repeating movements of the affected limbs, Lobatz said.
With each repetition, the new brain connections are strengthened. This can be done much more efficiently with a robot, he said. While a therapist might help a patient do 50 or 60 repetitions during a typical session, a robot can assist in several hundred repetitions.
“The dose of therapy is increased with the use of robotics,” Lobatz said.
Research indicates that robotic therapy improves patients’ medical outcomes compared to traditional therapy, he added.
As for prosthetics, they have come a long way since the simple mechanical assists such as peg legs or hooks for hands. Today’s prosthetics are much lighter and more flexible, and they increasingly incorporate electronics that perform movements based on triggers from remaining muscles or even by nerve impulses.
Losing a limb can play tricks on the brain, such as in “phantom limb syndrome,” in which a person appears to feel sensations from a missing limb. That’s because the parts of the brain that receives senses and sends movement commands to the limb is intact, but its connection is missing.
By using a prosthetic device, the patient can enable the brain to adapt. Some of the newer devices even restore a sense of touch, allowing the prosthetics to pick up delicate objects without crushing them.
And ultimately, the prospect of actual regeneration of missing brain parts might become a reality through stem cells, Lobatz said. This approach is still experimental.
In San Diego, people with Parkinson’s disease would be able to receive replacement brain cells grown from their own tissues if a proposed project involving Scripps Clinic and The Scripps Research Institute is approved. The replacement cells are intended to produce the neurotransmitter dopamine, which Parkinson’s patients lack.
This route is being approached carefully because unpredictable effects have been known to arise with similar approaches, Lobatz said.
“There’s a ways to go… but it certainly is the future of what we’re looking at, in addition to all the other technology that we use,” he said.
Post-traumatic stress disorder, or PTSD, is a psychiatric disturbance that can occur after life-threatening or extremely stressful events. The affected constantly relive those events.
PTSD may lead patients to withdraw from everyday life, as ordinary stimuli can be perceived as threatening.
While the condition is often associated with troops and veterans, anyone who experiences traumatic events can be affected. And while the diagnosis is psychological, detectable biological changes accompany the disorder.
About 60 percent of men and 50 percent of women experience at least one trauma in their lives, according to the U.S. Department of Veterans Affairs. Most recover without suffering PTSD. However, up to 8 percent will develop PTSD at some point.
Women are more likely to experience trauma from sexual assault and child sexual abuse. Men are more likely to be traumatized by accidents, assault, combat and disasters or by witnessing death or injury, according to the U.S. Department of Veterans Affairs.
Children are more likely to develop PTSD if their mother is affected, a 2013 study concluded. The study was performed on Israeli mothers and children who were exposed to rocket fire from Gaza during operation Cast Lead.
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