1 November 2005 Application of infrared light for in vivo neural stimulation
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J. of Biomedical Optics, 10(6), 064003 (2005). doi:10.1117/1.2121772
A novel method for damage-free, artifact-free stimulation of neural tissue using pulsed, low-energy infrared laser light is presented. Optical stimulation elicits compound nerve and muscle potentials similar to responses obtained with conventional electrical neural stimulation in a rat sciatic nerve model. Stimulation and damage thresholds were determined as a function of wavelength using a tunable free electron laser source (λ=2 to 10 µm) and a solid state holmium:YAG laser (λ=2.12 µm). Threshold radiant exposure required for stimulation varies with wavelength from 0.312 J/cm2 (λ=3 µm) to 1.22 J/cm2 (λ=2.1 µm). Histological analysis indicates no discernable thermal damage with suprathreshold stimulation. The largest damage/stimulation threshold ratios (<6) were at wavelengths corresponding to valleys in the IR spectrum of soft tissue absorption (4 and 2.1 µm). Furthermore, optical stimulation can be used to generate a spatially selective response in small fascicles of the sciatic nerve that has significant advantages (e.g., noncontact, spatial resolution, lack of stimulation artifact) over conventional electrical methods in diagnostic and therapeutic procedures in neuroscience, neurology, and neurosurgery.
Jonathon D. Wells, Chris Kao, E. Duco Jansen, Peter E. Konrad, Anita Mahadevan-Jansen, "Application of infrared light for in vivo neural stimulation," Journal of Biomedical Optics 10(6), 064003 (1 November 2005). http://dx.doi.org/10.1117/1.2121772


Tissue optics


Laser tissue interaction


Free electron lasers

Infrared radiation

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