CAREER: Effect of changes in power spectral density on neuromodulation

Loyola University Of Chicago, Chicago IL

Investigators

Abstract

Each year in the United States, approximately 2.9 million people experience a traumatic brain injury, more than 795,000 have a stroke, and about 17,700 experience a spinal cord injury. Some of these individuals lose their functional abilities and face challenges even in the basic activities of daily living. Neurorehabilitation is the usual choice of treatment for such neurological illnesses, and while few people will achieve full recovery of their motor functions, slight incremental improvements in the treatment outcomes may go a long way towards boosting their future quality of life. This proposal will investigate how best to use neuromodulation techniques to improve the outcomes of neurorehabilitation, by incorporating different electrical stimulation sequences to determine optimal ways of enhancing the effects of therapeutic exercises performed during routine physical therapy sessions. The theory behind the science of neurorehabilitation and neuromodulation is that therapeutic exercises can reorganize synaptic connections of the nervous system, and electrical stimulation can be applied to enhance the effects on the central nervous system, via a mechanism known as neuroplasticity. This project seeks to address the relevance between the power distribution of electrical stimulation and signs of neuroplasticity from a signal processing perspective, confirm the curative role of neuromodulation in neurorehabilitation applications, and provide insights as to how peripheral nerve stimulation can assist axon regeneration from a power distribution perspective. The study aims to provide a transformative educational experience to college and high school students who aspire to work in the biomedical engineering profession. Students with strong interests in engineering from Chicago’s public high schools will be invited to work with undergraduate researchers who will lead specific portions of the study. The PI hopes that conducting research on improving neurorehabilitation treatment outcomes will help these students realize that their proficiency in math and science can be translated into useful tools to help society and inspire them to pursue careers in biomedical engineering. This project will establish a fundamental theory of utilizing electrical modalities to enhance physical rehabilitation, in particular, the use of neuromodulation approaches to assist, support, and/or improve sensory or motor functions of persons who experience neurological ailments. The study will involve the use of an animal model to evaluate the effects of electrical stimulation on the nervous system by acquiring force and electromyography from the resulting neuromuscular contractions, focusing on the relationship between power spectral density and the central and peripheral nervous systems. Unlike previous studies that evaluate the varying effects of different stimulation frequencies, this study analyzes the power spectral density of the stimulation train, i.e., the power distribution within specific frequency bands. The plan is to evaluate individually the central and peripheral effects of a stimulation train over potentiation, depression, or other forms of neuroplasticity by looking at the correlation between the power spectral densities and the elicited muscle force profiles by conducting measurements before and after a nerve block. The hypothesis underlying this study is that the electrical stimulations that correspond to certain frequency components of a power spectrum may induce higher levels of potentiation via stimulation signals sent via afferent pathways (central contributions) and/or accelerate the recovery of peripheral nerve injury by regulating ion channels of Schwann cells (peripheral contributions). Three objectives will be explored: 1) refining the apparatus design to provide concurrent acquisition of electromyography and muscle force corresponding to selected frequency bands of electrical stimulation power spectral densities; 2) comparing the electromyography and force profiles before and after applying a nerve block proximal to the peripheral nerve stimulation site to evaluate the central contribution of electrical stimulation power spectral densities; 3) applying select frequency bands of electrical stimulation power spectral densities to compare their abilities to accelerate recovery of peripheral nerve injury and to evaluate the peripheral contribution of electrical stimulation. The results derived from these studies are intended to provide a better understanding of how electrical stimulation can be used to modulate human neuromuscular systems, design devices that can generate desired brain and peripheral nerve stimulations, and provide guidance for planning clinical trials to test such devices. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.