Methods for use of EIT. Disclosed are: (1) EIT used to obtain a final solution to an EIT inverse problem for localizing tissues undergoing changes in impedance, which is used as a constraint on solving an EEG source localization inverse problem； (2) EIT used with MREIT, where the MREIT is used to constrain the solutions to the EIT inverse problem for the distribution of static tissue impedance； (3) EIT used with MREIT, where the MREIT is used to constrain the solutions to the EIT inverse problem for localizing tissues undergoing changes in impedance； and (4) EIT according to any of (1)-(3) as feedback for modifying at least one of the location, magnitude, and timing of currents injected for the purpose of neurostimulation.
