Use of the method of local cathodoluminescence in Si-TiO2 and Si-SiO2-TiO2 structures helps to elucidate the nature of centers influencing the operation of memristors. These measurements showed that electroforming leads to the appearance of luminescence in a 250-400 nm wavelength range in the external part of TiO2 layer characterized by high concentration of defects. This observation leads to a conclusion that a sharp interface is formed between dielectric layers of the structure, provides estimation of the absorption coefficient of TiO2 layer, and allows its bandgap width (3.3 eV) to be evaluated for the oxide layers formed by the given technology.