Anatomic Constraints on Cognitive Theories of Category Specificity

Abstract:
Many cognitive theories of category specificity rely on underlying anatomical assumptions. Although functional neuroimaging offers the most promise for evaluating these competing claims, the findings to date are inconclusive primarily due to the small and inconsistent effects. We present a meta-analysis of category specific differences from 60 subjects performing seven different paradigms. The results across studies were highly significant although the individual effect sizes were small. Tasks involving semantic processing of tools consistently activated a region of the left posterior middle temporal gyrus. In contrast, tasks involving identification of living things consistently activated medial aspects of the anterior temporal poles bilaterally. This double dissociation demonstrates clear specialization within the semantic system and provides strong constraints for cognitive theories of category specificity. Specifically, the results support the theory that regions within a distributed semantic system preferentially respond to different types of semantic information.