Stimulus repetition improves performance on word recognition tasks. We used
magnetoencephalography (MEG) to investigate the brain areas associated wit
h this word repetition effect. The participants were eight men and six wome
n. The stimuli were 162 Japanese words each consisting of four katakana let
ters. The task was to read the words silently and memorize them for a subse
quent recognition test. The words were presented one by one and repeated on
ce after eight intervening words. Recordings were taken from bilateral temp
oral sites of the brain and the responses to the second presentations of th
e words were compared with those to the first presentations of the same wor
ds. Clear magnetic responses were observed in both the left and right hemis
pheres. In both hemispheres, the responses to the second words were signifi
cantly smaller than those to the first words, 250-600 ms after the stimulus
onset: Multidipole source analyses showed that the activities were reduced
by repetition in the bilateral peri-Sylvian areas, the bilateral medial te
mporal lobes, and the left angular gyrus.