A double dissociation between the meanings of action verbs and locative prepositions

We describe two patients who manifested opposite patterns of performance on test batteries that evaluated production, comprehension, and semantic analysis of action verbs on the one hand (e.g. smile, wave, run) and locative prepositions on the other (e.g. in, on, over). JP failed all of the verb tests but passed all of the preposition tests, suggesting impaired knowledge of the meanings of action verbs but intact knowledge of the meanings of locative prepositions. In contrast, RR exhibited the reverse dissociation: he passed many of the verb tests but failed all of the preposition tests, suggesting mostly intact knowledge of the meanings of action verbs but impaired knowledge of the meanings of locative prepositions. This behavioral double dissociation reflects the fact that the two categories of words differ along several conceptual parameters. To a large extent, the patients exhibited a neuroanatomical double dissociation as well, since JP's lesion is predominantly in the left frontal operculum whereas RR's is predominantly in the left inferior parietal lobe and the posterior superior temporal region. This constitutes preliminary evidence that the meanings of action verbs and locative prepositions are represented by partially independent neural networks in the brain.