Infrared neurostimulation of earthworm: from modeling to experiment

Abstract

Infrared neurostimulation (INS) is a new approach for modulation or control of neuronal pulses. Recently, different studies have been presented to investigate the origin of generation of the action potentials during INS, and it seems that the photothermal mechanism has an important role during INS. So, spatial and temporal temperature changes are important parameters, because the heating of neural tissue can excite or block the activity of neurons and an excess deposit of thermal energy could damage the neural tissues. We aim to explore the effects of heat diffusion during INS. We model the generation of action potential using the photothermal mechanism to study the changes of electrical properties of the membrane of neural cell in the earthworm (as a simple neuronal network) during INS. The variation of electrical properties of the membrane causes the changes in the concentration of ions such as K + and Na + inside the cells, which can originate the action potentials. This study includes three sections: (1) exploring the effect of laser light properties (wavelength of 1450 and 1550 nm, repetition rate and energy per pulse) on the measurement of temperature rise inside a phantom similar to neuronal tissue, (2) theoretical modeling to predict the generation of action potentials induced by the local temperature rise inside the neuronal network of earthworm, and (3) detecting the variation of voltage of peripheral nervous system of the earthworm during INS. This modeling can help us to better understanding the mechanism of the blocking and controlling the action potentials for in-vivo applications in the brain cognitive studies and treatment of some neuron system diseases.