Modeling of the temporal effects of heating during infrared neural stimulation.

A model of infrared neural stimulation (INS) has been developed to allow the temporal characteristics of different stimulation parameters and geometries to be better understood. The model uses a finite element approach to solve the heat equation and allow detailed analysis of heat during INS with both microsecond and millisecond laser pulses. When compared with experimental data, the model provides insight into the mechanisms behind INS. In particular, the analysis suggests that there may be two broad regimes of INS: the process tends to be limited by the total pulse energy for pulse lengths below 100 μs, while the temperature gradient with respect to time becomes more important above 100 μs.