| |
Abstract:
Abstract: Smith et al. (1998) and others have proposed a
tripartite model of the neural circuitry involved in verbal working
memory. According to this model, each cognitive component, storage,
rehearsal, and executive processes, is based on a separate set of
neural regions. Storage is mediated by posterior regions,
especially the posterior parietal region, whereas rehearsal is
mediated by anterior language areas, such as Broca's area. Finally,
executive processes are thought to be governed by prefrontal
regions, especially dorsolateral and ventrolateral prefrontal
regions. In a recent PET experiment, we demonstrated that adding an
inhibitory demand to an item-recognition task activated
ventrolateral prefrontal cortex (Brodmann's Area [BA] 45) (Jonides
et al., 1998). Here we report results from an fMRI experiment
designed to explore the neural regions involved in processing
temporal order information. We contrast activation during
item-recognition ("did you see this item?") with a task that
requires participants to remember and respond to the order of the
item presentation ("are these items in the correct order?"). In
addition to activation in typical storage-plus-rehearsal sites
(posterior parietal, premotor, Broca's area), we observe activation
in the dorsolateral prefrontal cortex in the temporal order task.
These results taken together with the results from our inhibition
experiment represent a double-dissociation in prefrontal cortex
between two different types of executive processing. Supported by
NIA (AG130287).
|
