RESPONSES TO SILENT KANJI READING OF THE NATIVE JAPANESE AND GERMAN IN TASK SUBTRACTION MAGNETOENCEPHALOGRAPHY

The neuromagnetic activities evoked by semantic processing were locali zed by magnetoencephalography (MEG). We observed distinct time courses of the activities in native speaking Japanese subjects (Japanese spea ker) and German subjects (German speaker) during silent reading of Jap anese letters; Kanji and meaningless figures made by deforming the Ara bian letters. There were significant differences in amplitude of the a ctivities between Kanji and meaningless figure stimuli. The responses with meaningless figure stimuli were subtracted from those with Kanji stimuli to demonstrate the semantic responses. Earlier responses peake d at about 273.3 +/- 50.8 and 245.0 +/- 23.8 ms (mean +/- S.D.) and we re mainly located in the right fusiform gyrus (FuG) in the Japanese an d German speakers, respectively. All the Japanese speakers constantly showed additional later responses in the left superior temporal gyrus (STG) and the supramarginal gyrus (SmG) at approximately 616.1 +/- 105 .5 ms, whereas no further activity was observed in the German speakers who did not know the meaning of each Kanji. Because the later respons es in the STG and SmG in the Japanese speakers were only observed in t heir dominant hemisphere, we believe the source of these responses to be part of the neural basis of Kanji semantic processing. The task sub traction MEG analysis could be a powerful method to discriminate disti nct responses and visualize the neural networks involved in semantic p rocessing. (C) 1998 Elsevier Science B.V. All rights reserved.