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Show Magnetic Stimulation of Peripheral Nerves Eric Tuday and Professor Ken Horch Department of Bioengineering Counterclockwise Magnetic Stimulation Setup It is possible to stimulate the peripheral nervous system using a magnetic coil. Observations have been made that suggest the magnetic coils are able to produce an action potential (an electrical signal the body uses for communication) that travels in only one direction. This is unique because conventional stimulation creates an action potential that propagates in both directions from the site of stimulation. This type of technology could be implemented in the creation of a non-chemical form of anesthesia, which would have many benefits such as decreased costs and recovery times. It is hypothesized that if two unidirectional action potentials were made to collide, they would temporarily inactivate the nerve allowing to signals to pass by (including pain signals). With continued stimulation, the nerve block could be maintained for an indefinite amount of time. However, there is no quantitative proof of the existence of unidirectional action potentials. The objective of this project is to collect quantifiable data to prove the existence of unidirectional action potentials using human sub-jects. The data is collected as surface recordings of electrical activity in the muscles of the forearm and in the somatosensory cortex region of the brain. Electromyographic (EMG) and somatosensory evoked potential (SEP) recordings are made while a subject is being stimulated with a magnetic coil. The coil is maneuvered to a loca-tion on the upper arm where physical effects are being elicited that are though to be indicative of the production of unidirectional action potentials. The coil is then locked into place with a mechanical system, the upper arm is stimulated with the magnetic coil, and then the data is acquired by a computer. The raw data is collected with Labview and analyzed with Matlab. The analyzed data shows a dramatic difference of the ratios of EMG activity to SEP activity between current direc-tion in the coil (i.e. clockwise (CW) vs. counterclockwise (CCW)). The means of the ratios across all twenty subjects forCW and CCW were submitted to an ANOVA test with a P-value< 2E-16. This data suggests that unidirectional action potentials can be created using magnetic stimulation and the directionality of the action potential can be controlled by the current direction in the stimulating coil. |
