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Abstract:
Adaptive behavior requires the efficient filtering of goal-relevant from goal-irrelevant information.
Ambiguous information inherent in natural situations therefore demands not
only the selection of goal-relevant information, but also cognitive control over interfering
irrelevant information.
The first question addressed in this thesis is, how does ambiguity influence the selection
of relevant information during preparation for an upcoming task? A second aim was to
further specify the role of the lateral prefrontal cortex (LPFC) in the selection of taskrelevant
information during the process of task preparation.
In order to reveal brain regions involved in the selection of relevant information in conditions
containing an interfering irrelevant component, a task switching experiment was
employed in which the congruency of two cue dimensions was manipulated in a Strooplike
manner. Although expected activation patterns attributable to this manipulation were
discovered in regions within the LPFC, a clear functional dissociation between specific
activation loci, i.e. inferior frontal junction area (IFJ) and posterior part of the inferior
frontal sulcus (pIFS), independently involved in selection of task-relevant cue information
from those involved in control of interfering irrelevant information was not possible.
In a second experiment the regions found in the previous study were targeted by employing
a novel cue manipulation in a visual search like manner. In this study, the cue
manipulation again led to activation in the pIFS and the IFJ. As hypothesized, region of
interest analyses demonstrated that in the context of ambiguity during task preparation,
the pIFS is more involved in selection of task-relevant information, while the IFJ shows
more sensitivity to the cue manipulation which requires interference control.
Through careful manipulation of the degree of ambiguity inherent in the task cue, the
studies presented here contribute to a finer understanding of the complex functional neuroanatomical
partialization of the LPFC.
