Project Summary/Abstract: During recent years, neuromodulation techniques such as transcranial direct current stimulation (tDCS), transcranial magnetic stimulation (TMS) and deep brain stimulation (DBS), as well as alternative methods using optical and ultrasonic modulations, have become an important means to study how complex neural circuits interact in the brain, to manipulate human cognition and to treat brain disorders. Magnetic resonance imaging (MRI) can now be performed either concurrently with or pre and post these neuromodulation techniques to visualize their effects on the human brain, to understand the neurophysiological mechanism and to improve their efficacy. This topic is highly relevant to the theme and growing interests of ISMRM for MRI guided therapy and MRI with implants. It also aligns with the goals of the NIH BRAIN Initiative and public interest in brain-computer interfaces such as Elon Musk’s Neuralink. The proposed ISMRM workshop on “MRI in Neuromodulation: Target Engagement, Neural Mechanism, and Biomarker Development” will bring together a diverse group of scientists and clinicians as well as industry partners who are interested in developing and applying advanced MRI techniques to visualize, understand and quantify neuromodulation effects on the human brain. This workshop will be the first of its kind on the topic of MRI in neuromodulation in ISMRM history. The proposed 2.5 days workshop will take place Oct 17-19, 2022 on the NIH campus in Bethesda MD. The program will be designed for both senior investigators and junior scientists. The organizing committee will also emphasize attendance by trainee members of ISMRM, underrepresented groups and engage the international research community, and will work with industry partners to secure funding to provide travel support for trainees. The meeting will include invited and proffered oral presentations as well as short power-pitch poster sessions. The workshop’s schedule will integrate presentations with ample discussion periods covering advances in various MRI techniques for neuromodulation (electromagnetic field mapping, functional connectivity, arterial spin labeled perfusion and permeability, temperature and acoustic radiation force imaging etc), pre-clinical animal models and cellular-level mechanisms of neuromodulation, and safety issues related to MRI with neuromodulation devices. Existing and emerging clinical applications for MRI in neuromodulation and biomarker development will be discussed between academic and industry partners.