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

Abstract

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.

Figure 1

Frontal and anterior insula peaks included in the meta‐analyses (red, switching studies; green, Stroop studies) displayed on axial MR images of an individual brain in Talairach space. On each slice the peaks lying up to 4 mm above and up to 5 mm below the respective slice are shown. The variance of activation peaks makes it difficult to identify regions involved consistently in both paradigms before statistical treatment.

Figure 2

Results of the quantitative meta‐analyses. Displayed are above‐threshold voxels at the IFJ peak coordinates for switching (A) and Stroop studies (B). Results are shown on an individual brain in Talairach space and were interpolated to millimeter resolution for display purposes. Only frontal coordinates entered the meta‐analyses.

Figure 3

A: Overlap analysis at the IFJ for switch and Stroop meta‐analyses. B: Overlap analysis for the meta‐analytic results and the results from a functional imaging study. From the imaging study, the overlap from the switch vs. null event contrast and from the Stroop incongruent vs. neutral contrast are shown. These results, with the inclusion of an n‐back task, are reported in detail in Derrfuss et al. [2004]. Results are shown on an individual brain in Talairach space and were interpolated to millimeter resolution for display purposes. Only frontal coordinates entered the meta‐analyses.