Induction of Gamma Oscillations via Transcranial Temporal Interference Stimulation: A Human Head Phantom Study.

Transcranial temporal interference stimulation (tTIS) is a novel technique for the noninvasive stimulation of the human brain. This method activates deep brain structures through the application of high-frequency (>1 kHz) electrical potentials on the human scalp by using two pairs of electrodes. This study explores the feasibility of inducing oscillations in the gamma frequency band (30-100 Hz) using tTIS aiming to target deep brain structures within an in-house built realistic pediatric human head phantom model that mimics the electromagnetic properties of a human head. Dipolar potentials were measured using an oscilloscope connected to four dipoles located in pre-defined deep brain structures within the phantom. We used low-frequency amplitude-modulated envelopes to generate gamma oscillations (in low-and high-gamma frequencies: 40 and 70 Hz) between two stimulation channels. We observed that stimulation depicted low-and high-gamma oscillations in the right posterior orbital cortex successfully. Statistical analysis corroborated the finding of this study that oscillatory responses were higher in target compared to control (non-stimulating) structures (p<0.05). Our findings indicate that tTIS exhibits spatial specificity and effective induction of gamma oscillatory activity. Thus, tTIS has the potential to replace conventional invasive neurostimulation methods (e.g., deep brain stimulation) through effective and specified noninvasive neuromodulation.Clinical Relevance- Our findings support the future use of tTIS in order to treat neurological and psychiatric disorders by inducing noninvasive gamma-band-related neural activity.