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Proceedings Paper

Reducing peak temperatures during infrared inhibition of neural potentials
Author(s): Jeremy B. Ford; Michael W. Jenkins; Hillel J. Chiel; E. Duco Jansen
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Paper Abstract

Pulsed infrared (IR) light has been used in multiple animal models to inhibit neural activity. Duke et al. reported inhibition associated with a temperature increase of ~8°C in Aplysia californica buccal nerve 2 (BN2). There is no evidence that the current irradiation schemes alters nerve functionality, however lower temperatures provide a safer environment for sustained inhibition. Inhibition paradigms use a single optical fiber to deliver IR light, resulting in a single hotspot within the nerve. One proposed method for decreasing peak temperatures is to use a lower radiant exposure over a greater area, effectively heating the nerve more evenly. Preliminary computational modeling suggests that using two axially adjacent optical fibers reduces peak temperatures required for infrared neural inhibition (INI). This hypothesis is being validated in vitro in Aplysia. Pleural abdominal nerves were dissected out, and suction electrodes were applied to electrically stimulate and record neural activity. A custom probe (core diameters= 400 μm) was used to simultaneously apply IR light from two diode lasers (Lockheed-Martin, λ=1875nm) to the nerve and monitor the radiant exposure out of each. Radiant exposures required for inhibition using a single fiber were reduced by ~37.4% by using two axially adjacent optical fibers. While mechanisms behind infrared inhibition are not fully understood, data suggests that a threshold temperature is required. By reducing peak temperatures, neural block using IR light will subject nerves to lower peak temperatures and provide a more research and clinically relevant technology.

Paper Details

Date Published: 28 February 2017
PDF: 7 pages
Proc. SPIE 10052, Optogenetics and Optical Manipulation, 100520B (28 February 2017); doi: 10.1117/12.2250019
Show Author Affiliations
Jeremy B. Ford, Vanderbilt Univ. (United States)
Michael W. Jenkins, Case Western Reserve Univ. (United States)
Hillel J. Chiel, Case Western Reserve Univ. (United States)
E. Duco Jansen, Vanderbilt Univ. (United States)

Published in SPIE Proceedings Vol. 10052:
Optogenetics and Optical Manipulation
Samarendra K. Mohanty; Nitish V. Thakor; E. Duco Jansen, Editor(s)

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