title: Activation of the prefrontal cortex in a nonspatial working memory task with functional MRI.
abstract: Functional magnetic resonance imaging (fMRI) was used to examine the pattern of activity of the prefrontal cortex during performance of subjects in a nonspatial working memory task. Subjects observed sequences of letters and responded whenever a letter repeated with exactly one nonidentical letter intervening. In a comparison task, subjects monitored similar sequences of letters for any occurrence of a single, prespecified target letter. Functional scanning was performed using a newly developed spiral scan image acquisition technique that provides high-resolution, multislice scanning at approximately five times the rate usually possible on conventional equipment (an average of one image per second). Using these methods, activation of the middle and inferior frontal gyri was reliably observed within individual subjects during performance of the working memory task relative to the comparison task. Effect sizes (2-4%) closely approximated those that have been observed within primary sensory and motor cortices using similar fMRI techniques. Furthermore, activation increased and decreased with a time course that was highly consistent with the task manipulations. These findings corroborate the results of positron emission tomography studies, which suggest that the prefrontal cortex is engaged by tasks that rely on working memory. Furthermore, they demonstrate the applicability of newly developed fMRI techniques using conventional scanners to study the associative cortex in individual subjects. © 1994 Wiley-Liss, Inc.
authors.affiliation: Department of Psychiatry, University of Pittsburgh, Bethesda, Maryland; Department of Psychology, Bethesda, Maryland.
authors.forename: J D
authors.initials: JD
authors.lastname: Cohen
authors.forename: S D
authors.initials: SD
authors.lastname: Forman
authors.forename: T S
authors.initials: TS
authors.lastname: Braver
authors.forename: B J
authors.initials: BJ
authors.lastname: Casey
authors.forename: D
authors.initials: D
authors.lastname: Servan-Schreiber
authors.forename: D C
authors.initials: DC
authors.lastname: Noll
keywords: CPT; cognitive neuroscience; magnetic resonance imaging; neuroimaging; spiral scanning; topography