The Department of Health and Human Services, through the National Institutes of Health (NIH), invites research grant applications focused on developing PET and SPECT imaging ligands to study brain disorders. This funding opportunity aims to stimulate research into novel radioligands that can assess molecular targets related to central nervous system (CNS) disorders, thus aiding in understanding disease mechanisms and evaluating therapeutic candidates. Applications are due starting January 5, 2025, with a maximum project period of five years. Eligible applicants include higher education institutions, non-profits, for-profits, and government entities. The grants may cover projects involving clinical trials, but prior approvals are necessary. Comprehensive guidelines include expectations for rigorous research design, feasibility assessments, and justification for the proposed work. Collaborations with academic and industry partners are encouraged to accelerate the identification and development of relevant imaging probes. The application review process will prioritize the significance, innovation, approach, and expertise of the applicants, emphasizing the development of non-redundant tracers and adherence to NIH policies on data sharing and human subjects protections. This initiative is a critical step in advancing neuroimaging techniques for better understanding and treatment of CNS disorders, especially focusing on mental health and aging-related conditions.