Computational Model of Optogenetic Stimulation in a Peripheral Nerve

Abstract

Stimulation has been a key technique for studying underlying mechanisms of the nervous system. Electrical stimulation has been the predominant method for eliciting desired muscle responses for decades, yet methodologies remain invasive and low in selectivity of tissue stimulated. Current injection affects all local tissue types and can lead to damaging immune responses that threaten both nerves and equipment alike. Optogenetics provides a solution by increasing specificity and decreasing risk to tissue. With genetic modification, opsins (light-sensitive proteins) are added to neurons, and can be activated by light to cause neuron excitation. Initial in vivo studies in transgenic mice expressing the channelrhodopsin (ChR2) validate that multiple beams of light have an additive effect and increase the response from muscles innervated by the target nerve. A computer model simulates light beams entering nerve tissue. This serves as a tool to aid future animal studies by determining light emission parameters needed to stimulate selected regions deep in the interior of a given nerve.