Representations of semantic relations in the human cerebral cortex

Abstract

An essential aspect of human cognition is the ability to explicitly think about semantic relations between concepts. Neuroimaging studies have found that individual concepts are encoded by distributed patterns of cortical activity, but it is unclear how representations of semantic relations compare to concept representations in the brain. Some theoretical models suggest that relation representations are embedded within concept representations, while others suggest that relation representations are independent of any specific concept pair. We designed a study to compare how semantic relations and concepts are encoded across the cerebral cortex. To characterize how relations are encoded across cortex, fMRI was used to record brain activity while six participants each answered over one thousand questions about different semantic relations. We find that representations of relations are distinct from their relata. Our results further suggest that relations and concepts are represented in similar cortical regions, and that, within these regions, each location is preferentially selective for specific relations. Overall, these results suggest that in the human cerebral cortex, relations and concepts have distinct representations that share a common functional organization.