Figure 1.

To examine the variability of prefrontal activity specific to semantic retrieval across these conditions, property verifications were contrasted with a pseudoword letter detection task. Activity in the aLIPFC. A, The medial region is more active for abstract property verifications than for sensory-based knowledge. B, In contrast, a more lateral region shows a main effect of abstractness and an interaction with response difficulty. Activity in the frontodorsal regions of the left prefrontal cortex. C, The FPC shows greater activity for abstract semantic retrieval than for the perceptual properties with an interaction based on response difficulty. D, The DLPFC shows increased activation for the abstract property verifications. Error bars represent SEM.