Neural activation during an explicit categorization task: category- or feature-specific effects?

Previous lesion-deficit and functional imaging studies have suggested that there are distinct category-specific regions within the human brain. Using functional magnetic resonance imaging, we tested this claim with a task in which participants decided if two items, represented by words, were members of the same category. Signal changes detected for all pairs of items that were from the same category and for tool pairs were found in rostromedial BA 6, rostral cingulate, and at the BA 6/44 and BA 45/46 junctions. Activation was seen in BA 6 and the left BA 6/44 junction for fruits and vegetables pairs and only in rostromedial BA 6 for animal pairs. The common signal changes in the frontal lobes (BA 6/44) for the categories of fruits and vegetables and tools suggest that this region may be organized in a feature-specific, as opposed to a category-specific, manner.