A neural region of abstract working memory.

Over 350 years ago, Descartes proposed that the neural basis of consciousness must be a brain region in which sensory inputs are combined. Using fMRI, we identified at least one such area for working memory, the limited information held in mind, described by William James as the trailing edge of consciousness. Specifically, a region in the left intraparietal sulcus was found to demonstrate load-dependent activity for either visual stimuli (colored squares) or a combination of visual and auditory stimuli (spoken letters). This result was replicated across two experiments with different participants and methods. The results suggest that this brain region, previously well known for working memory of visually presented materials, actually holds or refers to information from more than one modality.