Rewiring brains therapeutically

It's a medical myth that adults cannot grow new brain cells. Indeed, neurogenesis has been accepted by the scientific community for several years. However, it is only now that the idea of using neurogenesis to help the brain recover from injury has come to the fore.

Gitendra Uswatte, associate professor of psychology at the University of Alabama at Birmingham and colleagues have used magnetic resonance imaging to demonstrate that a form of rehabilitation therapy developed by UAB neuroscientists in the early 1990s for treating the effects of stroke actually produces physical changes in the structure of the brain. The study is the first practical evidence that brain remodeling is possible. According to Uswatte and colleagues, writing in the journal Stroke, a publication of the American Heart Association, analysis of the MRI scans of stroke patients reveals that Constraint Induced (CI) movement therapy produces a significant increase in the amount of "grey matter" present in the brains of patients receiving the therapy.

"These findings open the door to the possibility that the brain can indeed recover from traumatic injury by creating new brain cells to replace those lost by injury," says Uswatte. "This changes all of our perspectives about what is possible in the brain," adds neuroscientist Edward Taub who developed CI therapy. "For years, science thought the adult brain was hardwired, with no ability to change or adapt. Now we have further proof of the concept of neuroplasticity, the brain's remarkable ability to respond to damage to compensate for the injury."

Graduate student team member Lynne Gauthier working in Taub's laboratory, recorded MRI images for sixteen stroke patients who received CI therapy and 20 control subjects who received another form of therapy.

Gauthier then used voxel-based morphometry (VBM) to measure the amount of grey matter in the outer layers of the brain and the hippocampus deep within the bran and associated with learning and memory. The results showed that grey matter was increased in the motor regions of the brain for the CI therapy group whereas there was no apparent change in those patients receiving conventional therapy. This increase corresponded to a similar increase in the ability of the patients' ability to use an affected arm in daily living.

"Interestingly, the patients who demonstrated the greatest improvement in use of the affected arm also showed the greatest increase in the amount of grey matter," Gauthier says.

Since the 1993 publication of CI therapy Taub's laboratory has also had promising results with other conditions, including traumatic brain injury, cerebral palsy and multiple sclerosis. "We've shown that CI therapy can harness the plasticity of the brain for therapeutic effect in conditions with few practical treatment options," Taub explains. "Coupling CI therapy with other factors affecting neuroplasticity, such as pharmacologic agents or electrical stimulation, may lead to exciting new avenues for research into a host of neurological diseases and developmental disabilities," he adds.

The researchers are yet to figure out precisely what it is about CI therapy that increases the amount of grey matter. CI therapy involves constraining a patient's "good" limb and so forcing them to persist with using their afflicted limb. Taub says there are several possibilities as to what happens to the brain during CI. "It may be due to an increase in the amount of blood vessels in the brain, or in the number of synaptic connections established between neurons," he says. The grey matter increase may also reflect an increase in the number of glial cells in the brain. But the most intriguing possibility, the researchers say, is that the brain is creating new neurons.

CI therapy has been demonstrated as an effective strategy for helping patients recover from stroke. Taub and others across the globe have observed significant clinical improvements in patients with this therapy, allowing patients to recover functionality in paralysed limbs, for instance. They have also seen functional changes in the brain, such as increased blood flow and an increase in neuronal activity. The new study confirms what Taub and his colleagues have long suspected, that the brain can remodel itself structurally following trauma.

The views represented in this article are solely those of the author and do not necessarily represent those of John Wiley and Sons, Ltd.