Simulation Study of Envelope Wave Electrical Nerve Stimulation Based on a Real Head Model

In recent years, the modulation of brain neural activity by applied electromagnetic fields has become a hot spot in neuroscience research. Transcranial direct current stimulation (tDCS) and transcranial alternating current stimulation (tACS) are two common non-invasive neuromodulation techniques. However, conventional tACS has limited stimulation effects in the deeper parts of the brain. In this study, a method of low and medium frequency envelope wave neurostimulation is proposed, and its effectiveness and safety are evaluated by simulation and human experiment. First, we built a real head model from head MRI image data and used the finite element method to calculate the current distribution of the envelope wave in the brain. Then, a single-compartment neuron model was constructed in NEURON software to simulate the action potential generation of neurons under different frequencies of electrical stimulation. Finally, a human experiment was conducted to investigate the threshold of human perception of envelope wave electrical stimulation. The results show that envelope wave can both increase the depth of stimulation and induce neurons to generate effective action potentials. In envelope wave electrical stimulation, the optimal modulating wave frequency was 50 Hz, and the carrier frequency was 2 kHz-3 kHz. This method is expected to play an important role in the non-invasive treatment of neurological and psychiatric disorders.