UC Irvine

Dystonia is a movement disorder that causes involuntary twisting and repetitive movements, which can impede the patient so much that they are unable to lead independent lives or even communicate clearly with the people around them. In recent decades, exogenous electrical stimulation, including deep brain stimulation (DBS) and peripheral nerve stimulation (PNS), has shown promising results in the treatment of movement disorders caused by abnormal neural activity. However, as with any tool, exogenous electrical stimulation is only as useful as its operator is skilled, and for optimal use, the operator must both know what to do, and how to do so. By studying the abnormal signal flow that causes dystonia, we can understand what needs to be fixed, and by studying the effects of electrical stimulation on the dystonic brain, we can learn how to control the response pattern to generate the desired effect for each individual patient.

I aimed to contribute to these topics by studying neural recordings from stereo-electroencephalography (sEEG) electrodes in thalamic nuclei and basal ganglia of pediatric patients with dystonia during intracranial and peripheral electrical stimulation. My results were multifold, highlighting the complexity of the brain’s response to exogenous stimulation.

I found that the initial transient neural response to exogenous stimulations differs from long-term steady state responses to constant stimulation, and that DBS evoked potentials (EPs) can be affected, in a highly heterogeneous way, by the intake of medications. I discovered novel, intricate, yet highly consistent EPs, and unearthed trends in how DBS EPs and their delay, amplitude, and even shape depends on the stimulation frequency. I helped generate models to describe the observed neural responses and even discover connections between invasive neurophysiological recordings and non-invasive imaging methods.

These results were made possible by my extensive work put into developing methods to accurately process the data, remove noise and artifacts, and automate processes wherever possible to reduce bias and save time for further analyses. Through these methods alone, I hope to have contributed to the field of engineering for an extended time to come.

While we may still just be scratching the surface, I am confident that my dissertation research has at least made a solid dent in the casing that holds the secret to using exogenous stimulation to elicit the optimal clinical effect for children with dystonia and other movement disorders.