Precise functional connections between the dorsal anterior cingulate cortex and areas recruited for physical inference

Abstract

Recent work has identified brain areas that are engaged when people predict how the physical behaviour of the world will unfold-an ability termed intuitive physics. Among the many unanswered questions about the neural mechanisms of intuitive physics is where the key inputs come from: Which brain regions connect up with intuitive physics processes to regulate when and how they are engaged in service of our goals? In the present work, we targeted the dorsal anterior cingulate cortex (dACC) for study based on characteristics that make it well-positioned to regulate intuitive physics processes. The dACC is richly interconnected with frontoparietal regions and is implicated in mapping contexts to actions, a process that would benefit from physical predictions to indicate which action(s) would produce the desired physical outcomes. We collected resting state functional magnetic resonance imaging (MRI) data in 17 participants and used independent task-related runs to find the pattern of activity during a physical inference task in each individual participant. We found that the strongest resting state functional connections of the dACC not only aligned well with physical inference-related activity at the group level, it also mirrored individual differences in the positioning of physics-related activity across participants. Our results suggest that the dACC might be a key structure for regulating the engagement of intuitive physics processes in the brain.

Keywords: anterior cingulate cortex; functional connectivity; intuitive physics; resting-state fMRI; social reasoning.

FIGURE 1

Brain regions engaged by physical prediction tasks (panel a) and the anterior cingulate cortex (ACC; panel b). Both the physical prediction‐related activity and the ACC are shown here on a single hemisphere but are present bilaterally

FIGURE 2

Example of the experimental task: Physical versus colour judgements with identical stimuli. After the text cue indicating the type of judgement to perform (physical or colour), participants viewed a video of the tower rotating in 360° that allowed them to see the arrangement from all sides. Each video was followed by a 2‐s response period

FIGURE 3

Group‐level resting state functional connectivity maps (12 subjects). (a) Functional connectivity of the dorsal anterior cingulate cortex (ACC), our primary target for investigation. Significant positive resting correlations are shown in red (p < 0.001, cluster‐corrected), and significant negative resting correlations are shown in blue (p < 0.001, cluster‐corrected). (b) Functional connectivity for three additional subdivisions of the ACC, shown here for comparison with the dorsal anterior cingulate cortex (dACC). Colour coding thresholds are the same as in (a)

FIGURE 4

Overlap between regions identified with the intuitive physics localizer and the voxels whose activity correlates positively with the dorsal anterior cingulate cortex (dACC). The proportion of voxels falling within the intuitive physics parcels is plotted as a function of the threshold applied to the functional connectivity maps, with increasingly stringent thresholds plotted as one moves rightward along the abscissa. The degree of overlap increased with successively stringent thresholds, ultimately reaching 100% overlap for the functional connectivity of both the left‐ and right‐hemisphere dACC. The intuitive physics parcels are outlined in white on the functional connectivity maps below, which show all significant (p < 0.001, cluster‐corrected) positive correlations

FIGURE 5

Within and between‐subject spatial correlations (correlations across voxels) between the resting state connectivity of the dorsal anterior cingulate cortex (ACC) and the physics–colour contrast. The connected points on each plot show a participants ‘within’ correlation (the pattern of their dorsal anterior cingulate cortex (dACC) connectivity compared with their own pattern of task‐related activity) and their corresponding ‘between’ correlation (the same participants dACC connectivity compared with the task‐related activity of other participants). We entered the full set of these correlation values into an analysis of variance (ANOVA) analysis to test for a main effect of within‐ versus between‐subject correlations