Regional Cerebral Blood Flow in the Covert Reading of Kana Words: A Comparison with the Study of Reading Aloud Tasks

In our positron emission tomography (PET) studies on reading aloud of kanji (Japanese morphograms) and kana (Japanese phonograms) [1, 2], we found that the left or both posterior inferior frontal gyri (PIF; the left side includes part of Broca’s area) were activated together with the supplementary motor area (SMA), the left or both basal ganglia (predominantly the putamen), and the left or right thalamus and cerebellum. An unsolved problem in PET reading aloud studies, both English and Japanese [1–5], is whether the activation of the basal ganglia and thalamus occurs with language output or with the reading process (mainly comprehension). To address this question we performed a covert reading study (careful reading without utterance that differs from silent viewing of words) and compared it with our previous studies of reading aloud tasks.