Distinct and shared cortical regions of the human brain activated by pictorial depictions versus verbal descriptions: an fMRI study

Using fMRI, we observed that there were functionally disjunctive regions in the human brain that were specifically activated during the silent reading of sentences (i.e., the symbolical representation at the propositional level) but not during the perception of arranged objects (i.e., analogical representation), or vice versa: Parts of the left and right lingual gyri, the left fusiform gyrus, the left and right inferior occipital gyri, the right cuneus, and the left middle occipital gyrus were activated exclusively during the silent reading of sentences, whereas perception of the arranged objects activated distinct regions in the lingual gyrus, the declive, the fusiform gyrus, and the cuneus in the right hemisphere. A large proportion (86% in cortical volume) of the occipito-temporal regions was functionally conjunctive: these neural structures were activated during both silent reading of sentences and perception of arranged objects. We observed a similar trend of functional disjunction and conjunction between single words (the symbolical mode at the lexical level) and single objects (analogical mode): the degree of functional conjunction in the latter case was about 96%. These results suggest that the degree of functional disjunction between the pictorial depictions and the verbal descriptions tended to increase as the complexity of mental representation increased from the single word (lexical) level (4%) to the sentence (propositional) level (14%).