Functional Heterogeneity and Convergence in the Right Temporoparietal Junction

Abstract

The right temporoparietal junction (rTPJ) is engaged by tasks that manipulate biological motion processing, Theory of Mind attributions, and attention reorienting. The proximity of activations elicited by these tasks raises the question of whether these tasks share common cognitive component processes that are subserved by common neural substrates. Here, we used high-resolution whole-brain functional magnetic resonance imaging in a within-subjects design to determine whether these tasks activate common regions of the rTPJ. Each participant was presented with the 3 tasks in the same imaging session. In a whole-brain analysis, we found that only the right and left TPJs were activated by all 3 tasks. Multivoxel pattern analysis revealed that the regions of overlap could still discriminate the 3 tasks. Notably, we found significant cross-task classification in the right TPJ, which suggests a shared neural process between the 3 tasks. Taken together, these results support prior studies that have indicated functional heterogeneity within the rTPJ but also suggest a convergence of function within a region of overlap. These results also call for further investigation into the nature of the function subserved in this overlap region.

Keywords: Theory of Mind; attention reorienting; biological motion; fMRI; overlap.

Figure 1.

Activation maps from each task (cluster-corrected at P < 0.05) are displayed on a surface-rendered brain using AFNI′s SUMA tool (http://afni.nimh.nih.gov/afni/suma, last accessed October 20, 2014): (A) Bio > Scrambled contrast from the Biological Motion task, (B) Belief > Photo contrast from the Theory of Mind task, (C) Invalid > Valid contrast from the Attention-Reorienting task. For each activation map, the dorsal (top row), lateral (second row), medial (third row), and ventral (fourth row) surfaces are displayed. Activation maps are colored according to an activation gradient: red = Z > 3.1, orange = Z > 2.3, yellow = Z > 1.65. Only activations in red are considered significant activations. The regions in orange and yellow reflect regions that were considered in the two-way (Fig. 2, in red) and in the three-way (Fig. 1D) conjunctions, respectively. (D) The regions of overlap that were activated by all 3 tasks, that is, right TPJ/LOC and left TPJ. The regions of overlap in each hemisphere are from 1 cluster in volume space and only appear separated on the surface.

Figure 2.

Surface rendering of regions that were commonly activated by pairs of tasks: (A) Biological Motion and Theory of Mind (lateral surface), (B) Biological Motion and Attention Reorienting (lateral and ventral surfaces), and (C) Theory of Mind and Attention Reorienting (dorsal, lateral, medial, and ventral surfaces). Activation maps are colored according to an activation gradient: red = conjoint P < 0.001, yellow = conjoint P < 0.0025. Only activations in red are considered significant conjunctions. Regions in yellow reflect regions that were considered in the three-way conjunction (Fig. 1D). Surfaces views that had no activations are not shown. Only clusters of at least 20 voxels are shown.