Schnur, T. | bioRxiv Science

bioRxiv2021

Understanding Others Requires Right Temporoparietal and Inferior Frontal Regions

The human ability to infer other peoples knowledge and beliefs, known as theory of mind, is an essential component of social interactions. Theory of mind tasks activate frontal and temporoparietal regions of cortex in fMRI studies. However, it is unknown whether these regions are critical. We examined this question using multivariate voxel-based lesion symptom mapping in 22 patients with acute right hemisphere brain damage. Studies of acute patients eliminate questions of recovery and reorganization that plague long-term studies of lesioned patients. Damage to temporoparietal and inferior frontal regions impaired thinking about others perspectives. This impairment held even after adjustment for overall extent of brain damage and language comprehension, memory, comprehension, and attention abilities. These results provide evidence that right temporoparietal and inferior frontal regions are necessary for the human ability to reason about the knowledge and beliefs of others.

neuroscience↗

bioRxiv2020

Working Memory Capacities Neurally Dissociate: Evidence from Acute Stroke

Substantial behavioral evidence implies the existence of separable working memory (WM) components for maintaining phonological and semantic information. In contrast, only a few studies have addressed the neural basis of phonological vs. semantic WM using functional neuroimaging and none has used a lesion-symptom mapping (LSM) approach. Here we address this gap, reporting a multivariate LSM study of phonological and semantic WM for 94 individuals at the acute stage of left hemisphere stroke. Testing at the acute stage avoids issues of brain reorganization and the adoption of patient strategies for task performance. The LSM analyses for each WM component controlled for the other WM component and semantic and phonological knowledge at the single word level. For phonological WM, the regions uncovered included the supramarginal gyrus, argued to be the site of phonological storage, and several cortical and subcortical regions plausibly related to inner rehearsal. For semantic WM, inferior frontal regions and the angular gyrus were uncovered. The findings thus provide converging evidence for separable systems for phonological and semantic WM that are distinguished from the systems supporting long-term knowledge representations in those domains.

neuroscience↗