Jan Derrfuss

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. Hum Brain Mapp 25:22–34, 2005.

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.

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.

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.

The speed-accuracy tradeoff in the elderly brain: a structural model-based approach.

Even in the simplest laboratory tasks older adults generally take more time to respond than young adults. One of the reasons for this age-related slowing is that older adults are reluctant to commit errors, a cautious attitude that prompts them to accumulate more information before making a decision (Rabbitt, 1979). This suggests that age-related slowing may be partly due to unwillingness on behalf of elderly participants to adopt a fast-but-careless setting when asked. We investigate the neuroanatomical and neurocognitive basis of age-related slowing in a perceptual decision-making task where cues instructed young and old participants to respond either quickly or accurately. Mathematical modeling of the behavioral data confirmed that cueing for speed encouraged participants to set low response thresholds, but this was more evident in younger than older participants. Diffusion weighted structural images suggest that the more cautious threshold settings of older participants may be due to a reduction of white matter integrity in corticostriatal tracts that connect the pre-SMA to the striatum. These results are consistent with the striatal account of the speed-accuracy tradeoff according to which an increased emphasis on response speed increases the cortical input to the striatum, resulting in global disinhibition of the cortex. Our findings suggest that the unwillingness of older adults to adopt fast speed-accuracy tradeoff settings may not just reflect a strategic choice that is entirely under voluntary control, but that it may also reflect structural limitations: age-related decrements in brain connectivity.

Predicting errors from reconfiguration patterns in human brain networks

Task preparation is a complex cognitive process that implements anticipatory adjustments to facilitate future task performance. Little is known about quantitative network parameters governing this process in humans. Using functional magnetic resonance imaging (fMRI) and functional connectivity measurements, we show that the large-scale topology of the brain network involved in task preparation shows a pattern of dynamic reconfigurations that guides optimal behavior. This network could be decomposed into two distinct topological structures, an error-resilient core acting as a major hub that integrates most of the network’s communication and a predominantly sensory periphery showing more flexible network adaptations. During task preparation, core–periphery interactions were dynamically adjusted. Task-relevant visual areas showed a higher topological proximity to the network core and an enhancement in their local centrality and interconnectivity. Failure to reconfigure the network topology was predictive for errors, indicating that anticipatory network reconfigurations are crucial for successful task performance. On the basis of a unique network decoding approach, we also develop a general framework for the identification of characteristic patterns in complex networks, which is applicable to other fields in neuroscience that relate dynamic network properties to behavior.

Imitative response tendencies in patients with frontal brain lesions

It is widely accepted that patients with frontal lesions have problems inhibiting automatic response tendencies. Whereas inhibition deficits of overlearned responses have been extensively investigated using interference tasks like the Stroop task (J. R. Stroop, 1935), it is controversial whether patients with frontal brain lesions also have problems inhibiting imitative responses. Using an interference paradigm, the present study investigated imitative response tendencies in patients with frontal lesions. In addition, it tested whether patients deficient in the inhibition of imitative responses correspondingly have problems inhibiting overlearned responses. It was found that the group with frontal lesions displayed significantly stronger imitative response tendencies than the group with nonfrontal lesions. Furthermore, it was shown that the inhibition of imitative responses is functionally unrelated to Stroop interference.

Lost in localization: The need for a universal coordinate database

One of the great advantages of neuroimaging research is the use of an established and uniform coordinate system. This 3-D coordinate system allows for the comparison of activation locations across studies. In order to capitalize upon this advantage, however, researchers must be able to find relevant studies based upon activation locations. A number of research groups have embarked upon solutions to this problem, but to date there exists no exhaustive, universal coordinate database. In this commentary we outline the nature of the problem, its current solutions, and propose alternate solutions. We close with suggestions on how those in the field can facilitate the process of developing a universal coordinate database.

Meta-analysis of functional imaging data using replicator dynamics

Despite the rapidly growing number of meta‐analyses in functional neuroimaging, the field lacks formal mathematical tools for the quantitative and qualitative evaluation of meta‐analytic data. We propose to use replicator dynamics in the meta‐analysis of functional imaging data to address an important aspect of neuroimaging research, the search for functional networks of cortical areas that underlie a specific cognitive task. The replicator process requires as input only a list of activation locations, and it results in a network of locations that jointly show significant activation in most studies included in the meta‐analysis. These locations are likely to play a critical role in solving the investigated cognitive task. Our method was applied to a meta‐analysis of the Stroop interference task using data provided by the publicly accessible database BrainMap DBJ. Hum Brain Mapp 25:165–173, 2005.

Neural activations at the junction of the inferior frontal sulcus and the inferior precentral sulcus: Interindividual variability, reliability, and association with sulcal morphology

The sulcal morphology of the human frontal lobe is highly variable. Although the structural images usually acquired in functional magnetic resonance imaging studies provide information about this interindividual variability, this information is only rarely used to relate structure and function. Here, we investigated the spatial relationship between posterior frontolateral activations in a task‐switching paradigm and the junction of the inferior frontal sulcus and the inferior precentral sulcus (inferior frontal junction, IFJ) on an individual‐subject basis. Results show that, although variable in terms of stereotaxic coordinates, the posterior frontolateral activations observed in task‐switching are consistently and reliably located at the IFJ in the brains of individual participants. The IFJ shares such consistent localization with other nonprimary areas as motion‐sensitive area V5/MT and the frontal eye field. Building on tension‐based models of morphogenesis, this structure–function correspondence might indicate that the cytoarchitectonic area underlying activations of the IFJ develops at early stages of cortical folding. Hum Brain Mapp, 2009.