Event-related magnetic fields (ERFs) were recorded in seven subjects when they were presented with a rectangle and Japanese Kanji characters, followed by vocalizations. The ERF averages for the Kanji characters were different from those for the rectangle at latencies of about 100ms over the occipital lobe and 150-500ms over the temporo-parieto-occipital region. This observation suggests that the first stage of visual word processing might arise in the occipital lobe.
In some cases, difference between the ERFs for the Kanji characters and those for the rectangle were also seen in the frontal lobe at latencies greater than 250ms. This observation suggests that frontal lobe activity may be also involved in visual word processing.
Three equivalent current dipoles were estimated on the bilateral precentral gyrus (motor area) and the posterior part of the superior frontal gyros (supplementary motor area) at a latency of about 500ms during vocalization.
In some cases, early responses at latencies of less than 150ms were obtained in not only the occipital lobe but also the frontal and temporal lobes. This suggests that parallel processing might occur during visual word processing.
