Distinct and shared neural resources between processing of dynamic physical objects and spatial working memory

In human brains, portions of the frontoparietal cortex respond when people reason about the physical world (e.g. track objects, make predictions), and when people engage in a variety of demanding tasks (e.g. working memory, motor inhibition). Here, we use functional neuroimaging to address an open question about whether the same neural resources support both mental functions. Twenty-eight human adults (Mage = 26.5y; 17 female; 26 right handed) were scanned using functional magnetic resonance imaging (fMRI) while they (i) tracked the dynamics of physical objects (vs social agents), and (ii) performed a hard (vs easy) spatial working memory task. For each participant, we identified functional regions of interest (fROIs) that were maximally engaged by each task (physical > social; hard > easy), and studied their engagement in the held out task. We report three pieces of evidence that physical > social fROIs are recruited during the spatial working memory task. First, fROIs maximally engaged during physical (vs social) processing responded just as strongly during hard (vs easy) spatial working memory. Second, people with strong hard > easy responses in one set of regions also tended to have strong physical > social responses in the other set. Third, people with strong hard > easy responses in physical > social fROIs, but not in hard > easy fROIs, performed more strongly at spatial working memory in the scanner. These findings suggest that portions of the frontoparietal cortex that preferentially respond to physical (vs social) stimuli are involved in functions beyond physical reasoning: either spatial processing specifically, or attentionally demanding tasks in general.