Research Papers: Therapeutic

Analytical approaches for determining heat distributions and thermal criteria for infrared neural stimulation

[+] Author Affiliations
Bryan J. Norton, Jonathon D. Wells, Matthew D. Keller

Lockheed Martin Aculight, 22121 20th Avenue SE, Bothell, Washington 98021

Meghan A. Bowler

Lockheed Martin Aculight, 22121 20th Avenue SE, Bothell, Washington 98021

Vanderbilt University, Department of Biomedical Engineering, 5824 Stevenson Center, Nashville, Tennessee 37232

J. Biomed. Opt. 18(9), 098001 (Sep 03, 2013). doi:10.1117/1.JBO.18.9.098001
History: Received April 19, 2013; Revised July 19, 2013; Accepted July 24, 2013
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Abstract.  Infrared neural stimulation (INS) is becoming an important complementary tool to electrical stimulation. Since the mechanism of INS is photothermal, describing the laser-induced heat distribution is fundamental to determining the relationship between stimulation pulses and neural responses. This work developed both a framework describing the time evolution of the heat distribution induced by optical fluence and a new method to extract thermal criteria (e.g., temperature change and rate of change) for neural activation. To solve the general problem of describing the temperature distribution, a Green’s function solution to the heat diffusion equation was determined and convolved with the optical fluence. This provided a solution in the form of a single integral over time, from which closed-form solutions can be determined for special cases. This work also yielded an expression for thermal relaxation time, which provides a rigorous description of thermal confinement for INS. The developed framework was then applied to experimental data from the cochlea to extract the minimum temperature increase and rate of that increase to stimulate the cochlear spiral ganglion. This result, and similar analyses applied to other neural systems, can then shed light on the fundamental mechanism for INS and aid the development of optical neuroprostheses.

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© 2013 Society of Photo-Optical Instrumentation Engineers

Citation

Bryan J. Norton ; Meghan A. Bowler ; Jonathon D. Wells and Matthew D. Keller
"Analytical approaches for determining heat distributions and thermal criteria for infrared neural stimulation", J. Biomed. Opt. 18(9), 098001 (Sep 03, 2013). ; http://dx.doi.org/10.1117/1.JBO.18.9.098001


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