Eliciting Action Potentials from Epidermal Stimulation of Skin Receptors Using Ultrashort Laser Pulses

Abstract : Measurements of laser stimulated action potentials in the sciatic nerve of leopard frogs (Rana pipiens) were made using two ultrashort pulsed infrared lasers. The dorsal sides of the frog's hind limbs were exposed to 1540 nm and 1064 nm wavelengths at three separate spot sizes: 2 mm, 3 mm, and 4 mm. Energy density thresholds were determined for eliciting an action potential at each experimental condition. Results from these exposures showed similar evoked potential thresholds for both wavelengths. Skin ablation was observed at temperature increases as low as 0.7 degrees C, so we believe the primary skin damage mechanism to be stress confinement. Determining the method of receptor activation was outside the scope of this study. While the exact mechanism still remains unknown, it is possible to elicit action potentials from transdermal exposures of ultrashort lasers.