Quantifying tissue temperature changes induced by infrared neural stimulation: numerical simulation and MR...

Area of Science:

• Neuroscience
• Biomedical Engineering
• Biophysics

Background:

• Infrared neural stimulation (INS) uses light-to-thermal conversion for neuronal depolarization.
• Assessing thermal safety is crucial due to potential brain tissue damage.
• Quantitative data for central nervous system thermal effects are limited.

Purpose of the Study:

• To quantitatively measure and model temperature changes in ex vivo rat brains during INS.
• To evaluate the safety of INS parameters for biological tissues.

Main Methods:

• 7 Tesla MRI thermometry was used on ex vivo rat brains.
• Infrared pulse trains were delivered at intensities from 0.1-1.0 J/cm².
• The General BioHeat Transfer Model (GBHTM) simulated temperature changes.

Main Results:

• INS pulse trains caused transient temperature increases followed by rapid cooling.
• Multiple pulse trains with short intervals led to a temperature plateau.
• Temperature increases remained below 1°C at 0.1-0.5 J/cm² and below 2°C at 1.0 J/cm², within safe limits.

Conclusions:

• INS parameters commonly used in biological applications result in minimal, non-damaging temperature increases.
• The study provides quantitative evidence supporting the safety of current INS practices for brain tissue.