Lexical/semantic processing in dorsal left inferior frontal gyrus

Previous studies have not determined whether the dorsal left inferior frontal gyrus has a lexical or semantic function. This study conducted an event-related functional MRI experiment to explore its function using Japanese words and nonsense words in a syllable counting task. The word task activated a dorsal area (BA6/44) and a ventral area (BA45/47) more extensively than did the nonsense word task. The results indicate that the dorsal area also has lexical or semantic functions, despite that it has been related to phonological processing from studies using written stimuli. The more extensive activation by the word task might result from the same level of effort during phonological processing of Japanese words and nonsense words.