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Marcel Brass

Publications and source records attributed to Marcel Brass.

At least 19 recordsLinked to original sources
PubMed2006

Methodological and empirical issues when dissociating cue-related from task-related processes in the explicit task-cuing procedure.

In the explicit cuing version of the task-switching paradigm, each individual task is indicated by a unique task cue. Consequently, a task switch is accompanied by a cue switch. Recently, it has been proposed that priming of cue encoding contributes to the empirically observed switch costs. This proposal was experimentally supported by using a 2:1 mapping of cues to tasks, so that a cue switch does not necessarily imply a task switch. The results indeed suggested a substantial contribution of "cue-switch costs" to task-switch costs. Here we argue that the 2:1 mapping potentially leads to an underestimation of "pure" task-switch costs. To support this argument, we report the results of a new study in which we used "transition cues" that indicate the identity of the current task based on the identity of the preceding task. This new type of cue allows a full factorial manipulation of cue switches and task switches because it includes the condition in which a cue repetition can also indicate a task switch (i.e., when the "switch" cue is repeated). We discuss the methodological implications and argue that the present approach has merits relative to the previously used 2:1 mapping of cues to tasks.

Adult↗
PubMed2006

Voluntary selection of task sets revealed by functional magnetic resonance imaging.

In everyday life, we have to selectively adapt our behavior to different situations and tasks. In cognitive psychology, such adaptive behavior can be investigated with the task-switching paradigm. However, in contrast to everyday life, in experiments participants are unequivocally told which task to perform. The present functional magnetic resonance imaging (fMRI) study was set out to investigate processes that are relevant when participants can decide by their own which task to perform. The number of tasks to choose from was varied between a forced condition (no choice) and two voluntary selection conditions (two or three choices). We expected to find prolonged reaction times as well as higher activations within the midcingulate cortex for the choice conditions compared to the no-choice condition. The fMRI results revealed a significant activation difference for the choice conditions versus the no-choice condition. For the choice contrast, activation was found in the rostral cingulate zone (RCZ) as well as the superior parietal lobule and the posterior part of the intraparietal sulcus. These activations revealed no selection-specific difference between three and two choices. Finally, a post hoc analysis showed that the activation in the RCZ is not associated with higher task-dependent response conflict when participants can select a task set. Taken together, these findings indicate that distinct brain areas are involved in the voluntary selection of abstract task set information.

Adult↗
PubMed2005

Involvement of the inferior frontal junction in cognitive control: meta-analyses of switching and Stroop studies.

There is growing evidence that a specific region in the posterior frontolateral cortex is involved intimately in cognitive control processes. This region, located in the vicinity of the junction of the inferior frontal sulcus and the inferior precentral sulcus, was termed the inferior frontal junction (IFJ). The IFJ was shown to be involved in the updating of task representations and to be activated commonly in a within-subject investigation of a task-switching paradigm, the Stroop task, and a verbal n-back task. Here, we investigate the involvement of the IFJ in cognitive control by employing a meta-analytic approach. Two quantitative meta-analyses of functional magnetic resonance imaging (fMRI) studies were conducted. One meta-analysis included frontal activations from task-switching, set-shifting, and stimulus-response (S-R) reversal studies, the other included frontal activations from color-word Stroop studies. Results showed highly significant clustering of activations in the IFJ in both analyses. These results provide strong evidence for the consistent involvement of the IFJ in both switching and Stroop paradigms. Furthermore, they support our concept of areal specialization in the frontolateral cortex, which posits that it is not only the middorsolateral part that plays an important role in cognitive control, but also the IFJ. Finally, our results demonstrate how quantitative meta-analyses can be used to test hypotheses about the involvement of specific brain regions in cognitive control.

Brain Mapping↗
PubMed2005

Advance preparation and stimulus-induced interference in cued task switching: further insights from BOLD fMRI.

To switch from one cognitive task to another is thought to rely on additional control effort being indicated by performance costs relative to repeating the same task. This switch cost can be reduced by advance task preparation. In the present experiment the nature of advance preparation was investigated by comparing a situation where an explicit task cue was presented 2000 ms in advance of the target stimulus (CTI-2000) with a situation where cue and target were presented in close succession (CTI-100). We mapped the blood-oxygenation-level-dependent (BOLD) activation correlates of switch-related control effort and advance task preparation to test alternative explanations why advance preparation is reducing switch costs. A previously reported control-related cortical network of frontal and parietal brain areas emerged that was more strongly activated for switching between tasks. However, this was true exclusively for CTI-100 where no advance task preparation was possible. At CTI-2000 these same brain areas were equally engaged in both switch and repeat trials. For some of these areas, this common activation was time-locked to the presentation of both the cue as well as the target. Other areas were exclusively associated with target processing. The overall pattern of results suggests that advance task preparation is a common process of pre-activating (cue-locked activation) the currently relevant task set which does not face interference from a persisting N - 1 task set. During target processing the same brain areas are re-engaged (subsequent target-locked activation) to apply the pre-activated task set. Though being common to repeat and switch trials, advance preparation has a differential benefit for switch trials. This is because the instructed task set has time to settle into a stable state, thus becoming resistant against disruption from the previous task set, which is retrieved by the current target stimulus.

Adult↗
PubMed2005

The inhibition of imitative and overlearned responses: a functional double dissociation.

Neuropsychological research has established that the inhibition of dominant response tendencies is a function of the prefrontal cortex. These inhibitory mechanisms are tested using tasks like the Stroop task, in which the prepotency of the dominant response is based on a learned relationship of stimulus and response. However, it has also been reported that patients with prefrontal lesions may have problems inhibiting imitative responses. The question arises of whether the inhibition of overlearned and imitative responses entails the same or different functional mechanisms and cortical networks. In a recent neuropsychological study with prefrontal patients we found first evidence for such a dissociation. The present fMRI study further investigated this question by directly comparing brain activity in the inhibition of overlearned and imitative response tendencies. It emerges that response inhibition in the two tasks involves different neural networks. While the inhibition of overlearned responses requires a fronto-parietal network involved in interference control and task management, the inhibition of imitative responses involves cortical areas that are required to distinguish between self-generated and externally triggered motor representations. The only frontal brain area that showed an overlap was located in the right inferior frontal gyrus and is probably related to the generation of the stop signal.

Adult↗
PubMed2005

Internally generated and directly cued task sets: an investigation with fMRI.

It is widely acknowledged that the prefrontal cortex (PFC) plays a major role for goal-directed behaviour. In this context it is usually necessary to coordinate environmental information and internally represented intentions. Such goal-directed "endogenous control processes" can be investigated with the task-switching paradigm in which participants are required to alternate between different tasks. In the present study, we aimed at investigating different degrees of endogenous control by introducing two cue types with varying directness of the cue-task association. The "transition cues" informed the participants about repeating or switching the task but not about the task identity. Contrary to that, the "task cues" were directly associated with the upcoming task set. Since the transition cues are not directly associated with the task set they should require a higher demand of endogenous control than the task cues. The comparison of both cue types revealed frontolateral as well as frontomedian activations for the transition cue. We assume that the frontolateral activation reflects the coordination of information within working memory (WM) and the frontomedian cortex reflects the higher demand for endogenous control. Furthermore, regions of interest (ROIs) analyses indicate an important role for anterior regions along the left inferior frontal sulcus and frontomedian wall. This is suggested to reflect a functional gradient in anterior-posterior direction which is linked to the relative degree of required endogenous control.

Adult↗
PubMed2005

The role of the inferior frontal junction area in cognitive control.

Cognitive control processes refer to our ability to coordinate thoughts and actions in accordance with internal goals. In the fronto-lateral cortex such processes have been primarily related to mid-dorsolateral prefrontal cortex (mid-DLPFC). However, recent brain-imaging and meta-analytic studies suggest that a region located more posterior in the fronto-lateral cortex plays a pivotal role in cognitive control as well. This region has been termed the inferior frontal junction area and can be functionally and structurally distinguished from mid-DLPFC.

Animals↗
PubMed2005

Imitation: is cognitive neuroscience solving the correspondence problem?

Imitation poses a unique problem: how does the imitator know what pattern of motor activation will make their action look like that of the model? Specialist theories suggest that this correspondence problem has a unique solution; there are functional and neurological mechanisms dedicated to controlling imitation. Generalist theories propose that the problem is solved by general mechanisms of associative learning and action control. Recent research in cognitive neuroscience, stimulated by the discovery of mirror neurons, supports generalist solutions. Imitation is based on the automatic activation of motor representations by movement observation. These externally triggered motor representations are then used to reproduce the observed behaviour. This imitative capacity depends on learned perceptual-motor links. Finally, mechanisms distinguishing self from other are implicated in the inhibition of imitative behaviour.

Animals↗
PubMed2005

When hearing turns into playing: movement induction by auditory stimuli in pianists.

In this study, pianists were tested for learned associations between actions (movements on the piano) and their perceivable sensory effects (piano tones). Actions were examined that required the playing of two-tone sequences (intervals) in a four-choice paradigm. In Experiment 1, the intervals to be played were denoted by visual note stimuli. Concurrently with these imperative stimuli, task-irrelevant auditory distractor intervals were presented ("potential" action effects, congruent or incongruent). In Experiment 2, imperative stimuli were coloured squares, in order to exclude possible influences of spatial relationships of notes, responses, and auditory stimuli. In both experiments responses in the incongruent conditions were slower than those in the congruent conditions. Also, heard intervals actually "induced" false responses. The reaction time effects were more pronounced in Experiment 2. In nonmusicians (Experiment 3), no evidence for interference could be observed. Thus, our results show that in expert pianists potential action effects are able to induce corresponding actions, which demonstrates the existence of acquired action-effect associations in pianists.

Adult↗
PubMed2005

Who comes first? The role of the prefrontal and parietal cortex in cognitive 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.

Adult↗
PubMed2004

Selection for cognitive control: a functional magnetic resonance imaging study on the selection of task-relevant information.

The complex environment we live in makes it necessary to distinguish relevant from irrelevant information constantly and reliably. The aim of the present study was to investigate the neural substrate underlying the selection of task-relevant information. We devised a new paradigm in which participants had to switch between two different tasks that were instructed by task cues. The task cues had a relevant and an irrelevant cue dimension. In congruent trials, both cue dimensions indicated the same task; in incongruent trials, they indicated different tasks; and in neutral trials, only the relevant dimension indicated a task. By comparing trials in which both cue dimensions were informative (congruent and incongruent trials) with trials in which only the relevant dimension was informative (neutral trials), we were able to show that the lateral prefrontal cortex and a region in the intraparietal sulcus are involved in the selection of task-relevant information. Furthermore, the present paradigm allows the influence of the selected task and stimulus dimension to be investigated. No significant influence was found in the prefrontal cortex, indicating that this region serves a very abstract role in the selection of task-relevant information.

Behavior↗
PubMed2004

Action-effect coupling in pianists.

Recent theories have stressed the role of effect anticipation in action control. Such a mechanism requires the prior acquisition of integrated action-effect associations. The strength of such associations should directly depend on the amount of learning, and therefore be most pronounced in motor experts. Using an interference paradigm, we investigated whether evidence of such representations can be demonstrated in expert pianists. Participants were required to play chords on a keyboard in response to imperative visual stimuli. Concurrently, task-irrelevant auditory stimuli ("potential" action effects) were presented that were congruent or incongruent with the chords to be played. In Experiment 1 we found evidence that expert pianists, compared with non-musicians, have acquired such action-effects representations. Response times were slower when the auditory stimulus was incongruent with the required response. In order to ascertain the locus of interference, we varied imperative stimuli and responses in Experiments 2 and 3. The results indicate that, for the most part, interference occurs on the response level rather than on an abstract level. However, the perception of action effects also evokes processing of abstract features, like the concept of major-minor mode.

Acoustic Stimulation↗
PubMed2004

Cognitive control in the posterior frontolateral cortex: evidence from common activations in task coordination, interference control, and working memory.

Cognitive control has often been associated with activations of middorsolateral prefrontal cortex. However, recent evidence highlights the importance of a more posterior frontolateral region around the junction of the inferior frontal sulcus and the inferior precentral sulcus (the inferior frontal junction area, IFJ). In the present experiment, we investigated the involvement of the IFJ in a task-switching paradigm, a manual Stroop task, and a verbal n-back task in a within-session within-group design. After computing contrasts for the individual tasks, the resulting z maps were overlaid to identify areas commonly activated by these tasks. Common activations were found in the IFJ, in the pre-SMA extending into mesial BA 8, in the middle frontal gyrus bordering the inferior frontal sulcus, in the anterior insula, and in parietal and thalamic regions. These results indicate the existence of a network of prefrontal, parietal, and subcortical regions mediating cognitive control in task coordination, interference control, and working memory. In particular, the results provide evidence for the assumption that, in the frontolateral cortex, not only the middorsolateral region but also the IFJ plays an important role in cognitive control.

Adult↗
PubMed2004

Decomposing components of task preparation with functional magnetic resonance imaging.

It is widely acknowledged that the prefrontal cortex plays a major role in cognitive control processes. One important experimental paradigm for investigating such higher order cognitive control is the task-switching paradigm. This paradigm investigates the ability to switch flexibly between different task situations. In this context, it has been found that participants are able to anticipatorily prepare an upcoming task. This ability has been assumed to reflect endogenous cognitive control. However, it is difficult to isolate task preparation process from task execution using functional magnetic resonance imaging (fMRI). In the present study, we introduce a new experimental manipulation to investigate task preparation with fMRI. By manipulating the number of times a task was prepared, we could demonstrate that the left inferior frontal junction (IFJ) area (near the junction of inferior frontal sulcus and inferior precentral sulcus), the right inferior frontal gyrus, and the right intraparietal sulcus are involved in task preparation. By manipulating the cue-task mapping, we could further show that this activation is not related to cue encoding but to the updating of the relevant task representation. Based on these and previous results, we assume that the IFJ area constitutes a functionally separable division of the lateral prefrontal cortex. Finally, our data suggest that task preparation does not differ for switch and repetition trials in paradigms with a high proportion of switch trials, casting doubt on the assumption that an independent task set reconfiguration process takes place in the preparation interval.

Adult↗
PubMed2003

Event-related analysis for event types of fixed order and restricted spacing by temporal quantification of trial-averaged fMRI time courses.

PURPOSE: To develop a method for event-related fMRI that allows rapidly presented event sequences to be analyzed, without requiring transitions of different event-types to be counterbalanced. MATERIALS AND METHODS: A cued task switching procedure was investigated with an experimental trial comprising a visual task cue that indicated how to process a subsequent visual target stimulus. Cue and target were either presented quasi-simultaneously, separated by a 100 msec cue-target-interval (CTI100), or the target presentation was delayed by 2000 msec (CTI2000). To characterize the trial-related BOLD-response in terms of its temporal relation to the underlying event structure, the pattern of onset latency differences and peak latency differences for CTI2000 minus CTI100 was evaluated. Independent estimates of onset latencies and peak latencies were determined for preprocessed trial-averaged time courses by jackknife resampling. RESULTS: Validating results were obtained for two brain areas with known characteristics: the visual cortex (cue-locked plus target-locked activation) and the motor cortex (response-locked activation). Extending the analysis to prefrontal areas with a priori unknown characteristics differentiated between several meaningful temporal activation patterns. CONCLUSION: The method yielded a fine-grained temporal description of trial-related BOLD-responses that could be successfully used for the event-related analysis of an experimental design that was highly restricted with respect to event order and event spacing.

Adult↗
PubMed2003

Equivalence of cognitive processes in brain imaging and behavioral studies: evidence from task switching.

A growing number of studies on the higher-order cognitive functions of the human brain use brain-imaging techniques, such as functional magnetic resonance imaging (fMRI). For the validity and generality of fMRI results, it is important that the relevant cognitive processes are equivalent to those functioning in typical settings used in behavioral research. This equivalence could be, for example, endangered by different spatial frames of reference when lying in the scanner. In the present study, we tested whether the cognitive processes, as reflected in behavioral data in brain-imaging settings, are indeed functionally equivalent to those reflected in "purely" behavioral settings. To this end, we used a task-switching paradigm with a spatial component, increasing the likelihood to find effects of experimental setting. We compared the data of three different groups that only differed in testing environments (real, operating fMRI vs simulated fMRI vs standard behavioral with upright position of participants) but used otherwise strictly equivalent experimental conditions. Of importance for our validation purposes, unlike previous studies, we included a group with a behavioral setting, and we tested whether we would replicate a nontrivial, complex three-way interaction across all three groups. We replicated the predicted complex data pattern in all groups, suggesting functional equivalence of the underlying cognitive processes. We also found strongly increased reaction time (RT) levels in the two fMRI groups. We attribute this increase to unspecific distracting factors affecting late motor processes and discuss potential methodological implications of this increased baseline RT in the scanner.

Adolescent↗
PubMed2003

When the same response has different meanings: recoding the response meaning in the lateral prefrontal cortex.

The ability to adapt our behavioral repertoire to different situations and tasks is crucial for our behavioral control. Since the same motor behavior can have different meanings in different task situations, we often have to change the meaning of our responses when we get into a different task context. In a functional MRI experiment we manipulated this response recoding process. Subjects were required to execute two simple spatial tasks in a task switching paradigm. In one condition both tasks required the same set of responses, hence each response had two different meanings depending on the relevant task (bivalent condition). In the other condition subjects used a separate set of responses for each task (univalent condition). While subjects were required to recode the meaning when switching from one task to the next in the bivalent condition, response recoding was not required in the univalent condition. We demonstrate that the lateral prefrontal cortex is involved in recoding of response meaning. These results extend previous assumptions on the role of the prefrontal cortex in behavioral control.

Adult↗