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Item does not contain fulltext Verbal instructions are central to humans' capacity to learn new behaviors with minimal training, but the neurocognitive mechanisms involved in verbally instructed behaviors remain puzzling. Recent functional magnetic resonance imaging (fMRI) evidence suggests that the right middle frontal gyrus and dorsal premotor cortex (rMFG-dPMC) supports the translation of symbolic stimulus–response mappings into sensorimotor representations. Here, we set out to (1) replicate this finding, (2) investigate whether this region's involvement is specific to novel (vs. trained) instructions, and (3) study whether the rMFG-dPMC also shows differences in its (voxel) pattern response indicative of general cognitive processes of instruction implementation. Participants were shown instructions, which they either had to perform later or merely memorize. Orthogonal to this manipulation, the instructions were either entirely novel or had been trained before the fMRI session. Results replicate higher rMFG-dPMC activation levels during instruction implementation versus memorization and show how this difference is restricted to novel, but not trained, instruction presentations. Pattern similarity analyses at the voxel level further reveal more consistent neural pattern responses in the rMFG-dPMC during the implementation of novel versus trained instructions. In fact, this more consistent neural pattern response seemed to be specific to the first instruction presentation and disappeared after the instruction had been applied once. These results further support a role of the rMFG-dPMC in the implementation of novel task instructions and highlight potentially important differences in studying this region's gross activation levels versus (the consistency of) its response patterns. 15 p.

RWTH Aachen University, Diss., 2017; 124 pp. (2017). = RWTH Aachen University, Diss., 2017, Cognitive control is an essential factor of driving human behavior that enables us to respond flexibly to our environment in order to act in a goal-directed manner. Many every-day situations involve multimodal stimulation, such as visual and auditory input while driving a car. Cognitive control empowers us to respond to multimodal situations by focusing on relevant input (e.g., detour sign) while ignoring irrelevant input (e.g., car navigation system). So far, it has been assumed that cognitive control operates in a central and amodal way, free of modality-specific influences. In the present dissertation, this assumption is examined using the task switching paradigm.In the task switching paradigm, flexible cognitive adjustments to changes in the environment are investigated by asking participants to switch regularly between executing at least two competing tasks. The cued task switching paradigm comprises unpredictable task repetitions and switches. The relevant task is indicated by a cue and response times and error rates are measured to evaluate performance. A variety of switching related performance costs as well as stimulus-feature-related costs can be studied allowing for inferences regarding underlying cognitive processes (Kiesel et al., 2010; Vandierendonck, Liefooghe, & Verbruggen, 2010).In Kreutzfeldt, Stephan, Willmes, and Koch (2016a), we were interested in modality-specific preparatory effects on processes involved in updating and maintaining different tasks in working memory. To this end, we assessed alternation costs (i.e., performance decrement comparing performance in switch trials in mixed-tasks blocks and repetition trials in single-task blocks), which are associated with these processes, separately for the visual and auditory conditions. We varied the cue stimulus interval to assess the influence of prolonged preparation time on performance. Results indicated modality-specific preparation effects. Alternation costs were reduced more strongly for the auditory relative to the visual modality due to prolonged preparation time. This finding can be interpreted in terms of interference caused by verbal mediation and sensory input in working memory.In Kreutzfeldt et al. (2016b), we investigated modality-specific mechanisms of conflict adaptation. According to the conflict monitoring theory (Botvinick, Braver, Barch, Carter, & Cohen, 2001), reduced congruency effects (i.e., performance decrement in response to incongruent relative to congruent stimuli) after preceding conflict are due to reactively triggered, increased processing selectivity. In a cued modality switching paradigm, we observed this sequential modulation of congruency effects exclusively for modality repetitions, but not for modality switches. This finding provides evidence for modality-specific conflict adaptation and modality-specific task sets.In Kreutzfeldt, Stephan, Sturm, Willmes, and Koch (2015), we examined crossmodal selective attention in a cued modality switching paradigm with varied task requirements. Modality-specific congruency effects and switch costs (i.e., the performance decrement in response to switch relative to repetition trials; size varied as a function of stimulus modality) were observed as a function of task requirements. In the spatial-location task, congruency effects were larger for the visual than the auditory modality. In the spatial-verbal and spatial-numerical tasks, the auditory modality showed larger switch costs than the visual modality. These results are being discussed in relation to attentional biases (Meiran, Kessler, & Adi-Japha, 2008) and modality appropriateness (Welch & Warren, 1980), which was further addressed by computational modeling work.Computational modeling was used to depict potential modality-specific sources of cognitive control. The Compound Cue Model (Schneider & Logan, 2005, 2009) was used here as basis for our modality-specific modeling approach and to integrate the present findings. Taken together, the empirical findings and modeling approach suggest modality-specific influences on cognitive control., Published by Aachen

When participants rapidly switch between tasks that share the same stimuli and responses, task confusions (i.e., the accidental application of the wrong task) can occur. The present study investigated whether these task confusions result from failures of endogenous control (i.e., from ineffective task preparation) or from failures of exogenous control (i.e., from stimulus-induced task conflicts). The frequency of task confusions was estimated by considering the relative proportion of distractor errors, that is, errors that result when participants erroneously respond to the distractor associated with the alternative task. In Experiment 1, the efficiency of exogenous control was manipulated by varying the temporal order of target and distractor presentation. In Experiment 2, the efficiency of endogenous control was manipulated by varying the time available for preparing the task in advance. It turned out that only the efficiency of exogenous control but not the efficiency of endogenous control influenced the proportion of distractor errors. Accordingly, task confusions are more related to failures in exogenous control.

Cognitive control processes enable us to adjust our behavior to changing environmental demands. Although neuropsychological studies suggest that the critical cortical region for cognitive control is the prefrontal cortex, neuro-imaging studies have emphasized the interplay of prefrontal and parietal cortices. This raises the fundamental question about the different contributions of prefrontal and parietal areas in cognitive control. It was assumed that the prefrontal cortex biases processing in posterior brain regions. This assumption leads to the hypothesis that neural activity in the prefrontal cortex should precede parietal activity in cognitive control. The present study tested this assumption by combining results from functional magnetic resonance imaging (fMRI) providing high spatial resolution and event-related potentials (ERPs) to gain high temporal resolution. We collected ERP data using a modified task-switching paradigm. In this paradigm, a situation where the same task was indicated by two different cues was compared with a situation where two cues indicated different tasks. Only the latter condition required updating of the task set. Task-set updating was associated with a midline negative ERP deflection peaking around 470 msec. We placed dipoles in regions activated in a previous fMRI study that used the same paradigm (left inferior frontal junction, right inferior frontal gyrus, right parietal cortex) and fitted their directions and magnitudes to the ERP effect. The frontal dipoles contributed to the ERP effect earlier than the parietal dipole, providing support for the view that the prefrontal cortex is involved in updating of general task representations and biases relevant stimulus-response associations in the parietal cortex.