E.B. Writers of Dallas

Rewiring neural circuits through sensory- and medication-inspired stimulation

By Esther M. Bauer, correspondent, PULSE MAGAZINE, Dallas Morning News, 01/07/2003

Anyone who has ever cooed baby talk to an infant has assisted in the natural but intricate process of rewiring that child's brain.
Outwardly, the process involves repetition, recognition and reaction to familiar sounds. Inwardly, it is all about neurons. The child's brain is releasing millions of neurotransmitters in response to each familiar tone; in effect, rewiring the brain for certain sounds. The child's repertoire of recognized sounds quickly expands to include words and phrases that soon build into an entire language.
Stimulation and motivation are key to the rewiring process and motivation is something all healthy babies demonstrate with dogged persistence in learning how to talk and walk.
The natural rewiring process is noteworthy because of its possible implications for treating neurological disorders ranging from autism to stroke in children and adults.
Possible new treatment protocols would involve rewiring neural circuits through sensory- and medication-inspired stimulation or "the precise manipulation of brain plasticity," says Michael P. Kilgard, who has a Ph.D. in neuroscience and is a professor in the School of Human Development at the University of Texas at Dallas.
Dr. Kilgard is the principal investigator in the university's Cortical Plasticity Laboratory, where he is heading a five-year, $446,000 study called "Brain Plasticity and Neuro-Rehabilitation."
The study is funded by the James S. McDonnell Foundation of St. Louis and is part of the foundation's "Bridging Brain, Mind and Behavior" award.
"The same process of rewiring, responsible for learning new facts, is also how the brain learns to recover from injury, by physically remaking new connections between individual neurons. It requires the rewiring of millions, sometimes billions, of connections," says Dr. Kilgard.
"Neuro-plasticity is simply a change in the brain's function. If I look at a brain's response on day one and then I train you on something like a violin, piano or just shooting basketballs, that brain response is going to be different. Some neural plasticity has taken place. There has been a change, a rewiring."
The study seeks to develop dual treatment protocols of sensory rehabilitation techniques and medications that artificially excite brain neurotransmitters.
"It's not the case that you give an amphetamine and do a little speech therapy and 'boom,' a stroke patient is all better. The grant supports lab research to find out, first, how is the brain rewired when you combine certain sounds with certain drugs. We are going to try a whole variety of sounds and a whole variety of drugs because right now we don't know what the optimal way to rewire the brain is," says Dr. Kilgard.
Since the brains of highly motivated individuals release a number of neurotransmitters that encourage the rewiring process, medication-inspired motivation is a critical aspect of the study and stroke patients, in particular, may benefit.
Brain damage from stroke can result in paralysis and loss of language skills. Depression usually accompanies the loss and can impact a patient's motivation to recover. As a result, current treatment methods are often insufficient, even after months of rehabilitation, according to Dr. Kilgard.
In such cases, certain medications could provide the neurotransmitter boost necessary for faster learning, as demonstrated in a series of earlier studies, according to Dr. Kilgard.
"Giving amphetamines to stroke patients while they are practicing language skill and motor skills helps them recover faster. You help them be motivated, because when your brain has been damaged, it is very easy to fall into depression, very easy not to care," he says.
Medicine-induced motivation is critical for such patients, particularly in language skills since their intensity of participation in rehabilitation largely determines the extent of their recovery.
"One of the problems in stroke patients is you now need to rebuild those circuits from scratch, except you are 75 years old and you don't have six years to relearn language. You want to be speaking next month. We think we may be able to speed that up by several-fold.
"We give them amphetamines to rewire a new part of the brain to learn speech and then quickly simulate the developmental stages of speech until that person recovers function," says Dr. Kilgard.
Although far from proven, neuro-rehabilitation has the potential to transform the treatment of brain disorders in the same way that antibiotics and chemotherapy have changed the treatment of infection and cancer, he adds.
The study's laboratory experiments will provide the theoretical basis for future clinical trials to determine the effectiveness of targeted neuro-rehabilitation in humans. It may one day be possible to rebuild damaged circuits and restore lost function by guiding plasticity in much the same way that doctors now routinely manipulate the immune system, he says.
The lab studies will build on Dr. Kilgard's earlier research, including the reaction of medicated laboratory rats to patterns of sounds and tones. That research, including speeding up the pattern of tones, is resulting in a speeding up of the neurons of the rats' brains.
"In these animals, they could keep up with every single element. They heard every single pulse, where normal animals couldn't. So we are actually able to make a brain that's faster, but it's only faster in the auditory system that we have trained," says Dr. Kilgard.
The findings have relevance to a number of human disorders, including dyslexia.