Theoretical Analysis of the Effect of Temperature on Current Delivery to the Brain During tDCS

Abstract Background Transcranial direct current simulation (tDCS) is a non-invasive neuromodulation technique that has become increasingly popular as a potential therapeutic method for a variety of brain disorders. Since the treatment outcome may depend on the current density delivered to the brain cortical region, a significant challenge is to control the current dose reaching the cortical region. Objective and methods This study aims to investigate the effect of temperature on current delivery to the brain. We devised a method for modulating the amount of current delivered to the brain by changing the temperature of the scalp. We developed analytical and numerical models that describe the relationship between temperature and electrical properties of the scalp based on the following mechanisms: ion mobility and blood perfusion in scalp. Results and conclusions The current delivery to brain was investigated by changing the temperature between two electrodes that are attached to the surface of the scalp, within a tolerable physiological range. Results show that by increasing the temperature between two electrodes, a higher portion of current is shunted via the scalp and the proportion of the current that penetrates the scalp and skull into brain is decreased. On the other hand, cooling the area between two electrodes on the scalp increases the current delivery to the cortical region of the brain. Our results show that cooling the scalp during tDCS can be considered as a possible way to effectively control the current delivery to the brain and increase the efficacy of tDCS.