Disclosed herein are representative embodiments of methods, systems, and apparatus for enhancing or diminishing synaptic strength. Embodiments of the disclosed methods, systems, and apparatus can be used, for example, to complement the change in synaptic strength from transcranial direct current stimulation (“tDCS”) or transcranial magnetic stimulation (“TMS”) systems. One exemplary embodiment disclosed herein is a flexible housing having a top surface and a bottom surface. The flexible housing of this embodiment comprises a recessed cavity on the bottom surface that is configured to at least partially enclose an electrode of a transcranial direct current stimulator system. The flexible housing of this embodiment further comprises one or more apertures configured to provide access to the recessed cavity when the electrode is positioned within the recessed cavity. The flexible housing can further comprise one or more heating or cooling elements that can be selectively activated before, during, and/or after tDCS or TMS stimulation.
