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Abstract:
The neuroanatomical correlates of executive functions were
investigated using the dual-task paradigm of the psychological
refractory period. Research with this paradigm indicated that
dual-task costs depend on the requirements to schedule processes in
two concurrent tasks. We hypothesized that these scheduling
requirements determine the strength of dual-task specific
activation. 11 subjects had to perform an auditory and a visual
3-choice reaction task either separately (single tasks) or
concurrently (dual-task) during fMRI-measurement. In an easy
dual-task subjects performed both tasks in a pre-specified order.
In a hard dual-task condition subjects performed both tasks with
varying order, which increases the scheduling requirements in
dual-task processing. Behavioral data indicated larger dual-task
costs in the hard dual-task condition. An interaction analysis of
the fMRI data revealed areas along the inferior frontal sulcus
(IFS), the middle frontal gyrus (MFG) and the superior parietal
lobe (SPL) specifically activated by dual-task performance. These
areas were activated stronger in the hard compared to the easy
dual-task condition. The analysis of the single tasks revealed
activated areas in the MFG, which were located more dorsally and
anteriorly than the dual-task related areas. We conclude, that
areas in the IFS/MFG and the SPL are involved in dual-task
performance and that the strength of their activity can be
modulated by manipulating dual-task specific scheduling
requirements.
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