Evaluating models of the topographical organization of working memory function in frontal cortex with event-related fMRI

Many influential claims about the organization of working memory function in prefrontal cortex (PFC) have been developed and/or tested with functional neuroimaging methods featuring the blocking of behavioral trials and the averaging across blocks of neuroimaging signal. Interpretation of the results of these first-generation neuroimaging studies is subject to several inferential constraints that thereby weaken the models derived from them. We reassessed several models of the functional organization of working memory in PFC by examining or reanalyzing data that were not subject to the same inferential constraints from three event-related fMRI studies of working memory function performed in our laboratory (D'Esposito, Pestle, Ballard, & Lease, 1999; Pestle, Berger, & D'Esposito, 1999; Pestle & D'Esposito, 1999). This process permitted us to reject some of the models derived from first-generation neuroimaging data, to refine others, and to synthesize our results into a revised hybrid model of the working memory functions of PFC.