Brodmann area 31, also known as dorsal posterior cingulate area 31, is a subdivision of the cytoarchitecturally defined cingulate region of the cerebral cortex. In the human it occupies portions of the posterior cingulate gyrus and medial aspect of the parietal lobe. The region is typically discussed as having a unitary function because of a common pattern of relative deactivation observed during attentionally demanding tasks. One influential hypothesis is that the posterior cingulate cortex has a central role in supporting internally-directed cognition. It is a key node in the default mode network and shows increased activity when individuals retrieve autobiographical memories or plan for the future, as well as during unconstrained ‘rest’ when activity in the brain is mind wandering.<br>