Mechanistic Studies of Optical Nerve Stimulation

Infrared neural stimulation (INS) is a novel technology where infrared laser radiation is used to initiate action potentials in excitable tissues, including in nerves. The laser energy is absorbed by chromophores in the tissue and is converted into a spatio-temporal thermal gradient which results in the excitation of the target neuron. Compared to traditional methods of electrical neural modulation, INS has unique characteristics such as high spatial selectivity and artifact-free stimulation. While there are multiple studies that demonstrate the use of INS to modulate neural activity, the current understanding of the biophysical mechanism underlying INS is incomplete. A more complete understanding of the underlying biophysics of how a laser-induced thermal gradient triggers an action potential would allow for the prediction of neurophysiological outcomes of this novel process. However, because of the physical and temporal scale of the underlying dynamics, direct physical measurements on these systems is often not feasible, emphasizing the need for a computational model where individual components of the system can be tracked and varied independently. Additionally, there is evidence there could be a mechanical component to INS in addition to the thermal component. Therefore, we are developing an optical-thermal-mechanical-neural computational model that takes laser parameters and tissue properties as inputs to predict the effects on the neurophysiological outputs.

References

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Duke AR, Gault MA, Eckert J, Lu H, Jenkins MW, Chiel HJ, Jansen ED – Investigating the effects of infrared neural stimulation in the Aplysia californica – SPIE Photonics West, San Francisco CA, 2010.

Eckert J, Gault MA, Duke AJ, Jenkins MW, Lu H, Jansen ED, Rollins AM, Chiel HJ – Investigating optical methods for imaging and stimulating neurons – ShowCASE, Case Western University Symposium, Cleveland, OH (submitted).