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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.