A memristor device includes a first electrode, a second electrode, and a memristor layer disposed between the first electrode and the second electrode. The memristor layer is formed of a metal oxide. The memristor layer includes a plurality of regions that extend between the first electrode and the second electrode. The plurality of regions of the memristor layer are created with different concentrations of oxygen before electrical operation, and, during electrical operation, a voltage-conductance characteristic of the memristor device is controlled based on the different concentrations of oxygen of the plurality of regions. The controlling of the voltage-conductance characteristic includes increasing or decreasing the conductance of the memristor device toward a target conductance at a specific voltage.