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Abstract:
Past studies have revealed that the dorsolateral prefrontal
cortex (DLPFC) mediates the executive control of mental task
switching operations. The tasks in these studies, however, have
confounded various mental operations required in switching from one
task to another, such as goal shifting, rule activation, and
refocusing of attention to the relevant dimension of a visual
stimulus (e.g., the color of a word or shape). The DLPFC may be
responsible for this attention refocusing whereas other, as yet
undelineated, brain regions may mediate the other component mental
operations of task switching. To test this possibility, we have
conducted a positron emission tomography (PET) study in which
participants switched between tasks that involved two different
response mappings assigned to the same set of visual stimuli. Here
some of the same mental operations had to be employed as in
previous studies; however, attention refocusing to alternate
stimulus dimensions was unnecessary. We found less activity of the
DLPFC under these conditions, suggesting that the DLPFC plays an
important role for the refocusing of attention, but less so for
other mental operations in task switching and executive
control.
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