A magnetic coupled resonance transmission-based regulation of LTP in the Schaffer-CA1 region of the hippocampus by WP-μMS

Micro-magnetic stimulation (μMS) holds the potential for precise modulation of deep brain regions; however, the dependence on externally powered cables significantly limits experimental flexibility and long-term applicability. To overcome this limitation, this study developed a wireless passive micro-magnetic stimulation (WP-μMS) device based on magnetic coupled resonance transmission. The primary objective is to systematically investigate the effects of WP-μMS on long-term potentiation (LTP) in the hippocampal Schaffer-CA1 region across MHz-range frequencies and at magnetic field intensities below 1 mT, thereby expanding the parameter space for WP-μMS applications. This study first optimized the inductance parameters of the stimulation electrode to enhance efficacy and confirmed that the transmitting coil itself did not influence LTP in the hippocampal Schaffer-CA1 region. Based on this, the effects of magnetic stimulation at three frequencies (11 MHz, 8 MHz, and 5 MHz) were compared under a fixed magnetic field intensity of 0.67 mT. Then, the differential effects of 0.74 mT, 0.82 mT, and 0.98 mT were evaluated at a fixed frequency of 5 MHz. The results demonstrated that at a constant magnetic field intensity, all three frequencies enhanced LTP in the hippocampal Schaffer-CA1 region, with higher frequencies producing a more pronounced effect. At a constant frequency, the facilitatory effect of LTP becomes increasingly pronounced with the increase in the intensity of the stimulus magnetic field. These findings validate the feasibility of parameter-dependent modulation of hippocampal synaptic responses following LTP using WP-μMS within the MHz/mT parameter range and provide a foundation for future optimization of WP-μMS device parameters.