PhD, University of California at San Francisco
Principles of Cortical Plasticity
The brain is an incredibly sophisticated self-organizing system. When operating properly it has the amazing ability to optimize its function to solve nearly any computational problem. Most children, for example, can learn any of the hundreds of human languages with ease. It is easy to underestimate the complexity of such an enormous task until one observes the struggle of a child with a neurologic disorder that degrades the most important of human abilities: communication. We have every reason to believe that therapies will be developed to help even severely impaired children, but basic science research is desperately needed.
The brain operates by coordinating the activity of millions of neurons. Although we know a lot about these basic units of the brain, to understand how to help individuals with language impairments we need to know a lot more about how neurons work together. Just as it would be difficult to understand self-organizing ecological or economic systems through the study of individual animals or companies, it is nearly impossible to predict how millions of neurons learn to act in concert by studying individual neurons in isolation.
My laboratory employs several techniques to explore how the brain reorganizes itself when learning the sounds that contribute to human speech. The use of an animal model allows us to explore important self-organizing principles of the mammalian brain with a precision not possible in humans (Science, 1998). By activating the region of the brain that controls learning, we are able to directly observe the reorganization of millions of individual neurons as they learn the cues that are crucial to proper language acquisition in humans. By training animals to do complex acoustic discriminations, we can relate brain changes with perceptual improvements. By housing animals in complex environments, we have been able to document how natural experiences influence brain organization. Finally, by using stimulants we been exploring how these drugs could be used to facilitate human recovery from brain damage.
Each of these models to sheds light on different brain processes that may one day allow patients suffering from strokes and children with dyslexia or autism to regain their full potential. Though many mysteries remain about brain function, we are confident that we are close to exposing a set of general principles of self-organization that will be crucial for the development of effective intervention strategies for individuals suffering the nightmare that is life without language.
The primary objective of the research in my laboratory is to understand how experience rewires the brain. We are particularly interested in how experience with speech sounds alters the brain. We are presently combining speech training and environmental enrichment with pharmacological and electrical stimulation of the nervous system to develop a general theory of neural plasticity. Understanding the network-level changes that allow the brain to adapt to new situations and learn novel stimuli will aid in the development of new treatment strategies for neurological disorders including dyslexia, autism, and stroke.
Porter B.A., Khodaparast N., Fayyaz T., Cheung R.J., Ahmed S.S., Vrana W.A., Rennaker R.L. 2nd, Kilgard M.P. (in press). Repeatedly pairing vagus nerve stimulation with a movement reorganizes primary motor cortex. Cerebral Cortex.
Shetake J.A., Wolf J.T., Cheung R.J., Engineer C.T., Ram S.K., Kilgard M.P. (in press). Cortical activity patterns predict robust speech discrimination ability in noise. European Journal of Neuroscience.
Nichols J., Nichols A.R., Smirnakis S., Engineer N.D., Kilgard M.P., Atzori M. (2011). Vagus Nerve Stimulation Modulates Cortical Synchrony and Excitability through the Activation of Muscarinic Receptors. Neuroscience, 189:207-14.