A memory matrix (10) comprises rows and columns of cells, each cell comprising a resistance hysteresis element (24) and a threshold element (22) coupled in series between a row terminal and a column terminal of the cell (20). The resistance hysteresis element (24) has a mutually larger and smaller hysteresis thresholds of mutually opposite polarity respectively. Voltage differences are applied between the column terminals and the row terminals of cells (20) in a selected row, so as to perform read actions. These voltage differences have a read polarity so that the voltage across the cell (20) is in a direction corresponding to the larger hysteresis threshold. Voltage differences are applied between the column terminals and the row terminals of cells (20) in a selected row, so as to perform erase actions, all cells (20) of a selected row being erased collectively in the erase action. The voltage differences for erase actions have the read polarity. Furthermore voltage differences are applied between the column terminals and the row terminals of cells (20) in a selected row, so as to perform write actions. The voltage differences for the write actions have a write polarity corresponding to the smaller hysteresis threshold, for updating cells (20) that are selected dependent on write data.