The aim of the study was identification of the functional anatomy of the cerebral regions, whose activity correlates with increasing working memory load, irrespective of the stimulus type. To address this problem, the authors used a version of the n-back task with two levels of difficulty (2-back and 3-back) and two types of memory stimuli: letters and colorful abstract patterns. Brain activity was measured with functional MRI. The resulting statistical maps showed four cortical regions, whose activity was significantly higher during performance of 3-back tasks than during performance of 2-back tasks. These areas included dorso-lateral prefrontal cortex, representing continuous updating of working memory; anterior cingulate - region responsible for conflict monitoring. Two remaining regions were located within the left parietal lobe and their activity represented frontally controlled attentional bias (precuneus) and the passive storage of phonological information (supramarginal gyrus).