Regional brain activations differ for semantic features but not categories

Is human semantic knowledge neurally organised according to either category (e.g. living vs non-living) or attribute type (e.g. perceptual vs non-perceptual information)? Normal subjects were scanned using PET during a novel semantic production task, in which they generated either perceptual or non-perceptual information in response to names of living or non-living concepts. Analyses of blood flow in the temporal lobes revealed no significant differences associated with responses to living vs non-living concepts. Comparisons between retrieval of perceptual vs non-perceptual information, however, revealed significantly greater blood flow in left posterior inferior temporal cortex and right fusiform cortex associated with perceptual information and in left middle temporal cortex with non-perceptual information. These findings support a primarily attribute-based neural organisation of semantic knowledge