The effect of stimulus repetition on cortical magnetic responses evoked bywords and nonwords

Stimulus repetition improves performance and modulates event-related brain potentials in word recognition tasks. We recorded evoked magnetic responses from bilateral temporal sites of the brain to determine the cortical area related to the word repetition effect. Fourteen Japanese volunteers read wo rds or pronounceable nonwords, some of which occurred twice with a lag of e ight items. Clear magnetic responses were observed bilaterally. In the left hemisphere, a reduction of the magnetic responses by repetition was observ ed for words but not for nonwords in the latency range of 300-500 ms postst imulus. The sources of the responses were estimated to be in the left peris ylvian area adjacent to the auditory cortex and the left parietal area. Onl y the perisylvian source activity showed the reduction by the word repetiti on. The left perisylvian area was thus suggested to be related to the word repetition effect. The activity in this area might be associated with the l exical memory process. (C) 2001 Academic Press.