Project Summary/Abstract Non-invasive brain stimulation (NIBS) has attracted considerable interest in the cognitive neuroscience community, providing an important basic research tool to study brain function, with emerging clinical applications to enhance function in individuals with neurological disorders. Despite this potential, an emerging literature has highlighted concerns regarding the reliability and robustness of transcranial electric stimulation (tES), the primary NIBS method used to induce changes in brain plasticity through the application of subthreshold stimulation. These problems are likely related to the fact that tES systems can only induce modest electrical fields (E-field) at the cortical surface given that safety/tolerance issues limit the intensity of tES stimulation that can be delivered at the scalp. We developed a radically new NIBS approach, one in which subthreshold modulation of neural excitability is brought about via oscillating magnetic fields at kHZ frequencies. This system, referred to kTMP (kHz Transcranial Magnetic Perturbation) significantly increases the range of subthreshold E-field induction, and through modulation of the envelope of the kHz carrier frequency, can impose E-fields at physiological relevant frequencies. The three-year funding period will be used to conduct testing with human participants to assess the tolerability and efficacy of the system in producing changes in cortical physiology and behavior. If our expectations are confirmed, this system will introduce a powerful new method for modulating neural excitability and as such, provide clinicians with a promising new intervention in the treatment of neurological disorders.