An implantable microstimulator includes a plastic housing having a first end; an electronic subassembly; and a conductive plastic electrode disposed at the first end of the plastic housing and in electrical communication with the electronic subassembly. The image-display apparatus can have the liquid-crystal display panel or the like and can be mounted on a mobile phone, a PDA, and so forth, so as to process and display image data transmitted from outside sources. An objective function value for the investor is determined and maximized.