Sociotopy in the temporoparietal cortex: common versus distinct processes

Abstract

A major controversy in the social cognitive neurosciences evolved around the question whether activity in the posterior superior temporal sulcus and adjacent temporoparietal junction (pSTS/TPJ-region) evoked by various tasks represents a common process or distinct processes. To investigate this question, we employed functional magnetic resonance imaging (fMRI) while participants performed Biological Motion (BM), Theory-of-Mind (ToM) and Moral Judgment (MJ) tasks. Importantly, for each task we used the same newly developed animated stimuli. Indicative of a common process, we identified small clusters of overlapping activity for BM and ToM in right pSTS and for ToM and MJ in bilateral pSTS and left TPJ. Indicative of distinct processes, on the contrary, we detected extensive dissociable activity for BM in right pSTS, for ToM in bilateral pSTS and left TPJ, and for MJ in bilateral pSTS and TPJ. Thus, our data provide strong evidence for a combined two-staged process account: (i) the parsing of a stream of visual-spatial information, represented by activity in right pSTS, where neighboring and overlapping clusters of increased responses were found for all three tasks; (ii) increasingly more complex processing of the communicative significance of other people's behavior, represented by hierarchically increasing activity in left pSTS and bilateral TPJ elicited by ToM and MJ.

Fig. 1

Meta-analysis of studies on BM, ToM and MJ. The activation maxima as reported by previous studies on BM (blue), ToM (yellow) and MJ (green) are superimposed on a left sagittal (left panel) and right sagittal slice (right panel) of the posterior superior temporal sulcus and the temporo–parietal junction. Note, that the location of activation maxima for BM is slightly anterior and inferior to those of either ToM or MJ.

Fig. 2

Stimulus material. Each stimulus consisted of two picture frames, which were presented rapidly one after the other. The top panel shows the main conditions (a) bm, tom and mj from left to right. The lower panel shows the control conditions (b) om, aj and pnj from left to right. The timeline of presentation is reported on the right.

Fig. 3

Imaging results. The left panel shows the activity elicited by the three contrasts between each main condition and respective control condition, the upper right panel represents these results schematically. The lower right panel shows the intersection of the three contrast maps. Left panel: Focusing on the pSTS-region, a right sagittal, a coronal, and a left sagittal slice are shown at the coordinates (x = 60, y = −42, z = 6, MNI coordinates) and (−60/−42/6), respectively, for each of the contrasts. The activations of each contrast were thresholded at Z = 3.09. Blue (a): BM (bm > om), yellow (b): ToM (tom > aj), green (c): MJ (mj > pnj). Right upper panel: A schematic representation (d) highlights the hierarchically increasing recruitment of pSTS/TPJ sub-locations by the contrasts for BM (bm > om), ToM (tom > aj) and MJ (mj > pnj). Right lower panel: The upper three intersection images (e) show the sagittal, coronal and axial slices of a location in the right pSTS, the lower three (f) show the slices of a location in the left TPJ. The contrasts of BM, ToM and MJ were integrated into a single dataset. Distinct activity: blue: BM (bm > om), yellow: ToM (tom > aj), green: MJ (mj > pnj). Overlapping activity: orange: conjunction of BM and ToM (bm > om and tom > aj), red: conjunction of ToM and MJ (tom > aj AND mj > pnj).

Fig. 4

Correlations of the BOLD response with MASC scores in the left pSTS-ROI of ToM and MJ (tom > aj and mj > pnj). Scatter plots with regression lines reveal (a) a significant negative correlation between the amplitude of the BOLD response of the ToM contrast (tom > aj) and the MASC, but (b) no correlation with the BOLD response of the MJ contrast (mj > pnj).