Dissociating a common working memory network from different neural substrates of phonological and spatial stimulus processing.

Positron emission tomography was used to investigate common versus specific cortical regions for the maintenance of spatial versus phonological information in working memory (WM). Group and single-subject analyses of regional cerebral blood flow during a new 2 x 2 factorial n-back task were performed. Eight subjects had to memorize either phonological features or the location of serially presented syllables.