MECHANISMS OF INFRARED NERVE INHIBITION: COMPUTATIONAL MODELING AND EXPERIMENTAL VALIDATION

Abstract

Infrared laser (IR) irradiation has been shown to block action potential generation and propagation in both mammalian and non-mammalian nerves. This effect has been shown to be reversible, spatially precise, and appears safe. These properties make IR irradiation suitable to replace electrical stimulation as a neuromodulation technique in the future, especially for pain management. In order to achieve that objective, understanding the mechanism of block of action potential generation and propagation with infrared laser light is necessary, which is the major aim of this dissertation. A computational model has been developed that can predict the response of unmyelinated axons at elevated temperature, which results from infrared irradiation. The modeling results suggest that faster and elevated activation levels of potassium channels appear to be responsible for causing infrared inhibition. This modeling derived hypothesis is tested by observing that the effect of infrared irradiation in disrupted in the presence of potassium channel blocker. Computational model developed has also been utilized for parametric analysis by combining an optical thermal light distribution-heat transfer model with a neurophysiological model. This allows us to predict neural responses to realistic temperature distributions and provide design inputs for medical devices to minimize thermal damage during infrared nerve inhibition.