Lack of repetition priming effect on visual event-related potentials in schizophrenia.
BACKGROUND
The present study was designed to assess, using event-related potentials, whether aberrant semantic processing reported in schizophrenia results from primary semantic overactivation or contextual dysregulation.


METHODS
The visual event-related brain potentials were compared between 9 schizophrenic subjects and 16 normal control subjects performing two kinds of semantic categorization tasks with different nontarget stimuli: 1) nontargets comprising words, pseudowords, and unpronounceable foreign letters and 2) nontargets comprising initial presenting words, immediate repetition words, and delayed repetition words.


RESULTS
Schizophrenic subjects showed no evidence suggestive of a greater negative potential associated with words and pseudowords, but they did show a lack of amplitude change associated with immediately repeated words relative to that in control subjects.


CONCLUSIONS
These results suggest that aberrant semantic activation in schizophrenia results mainly from a failure to utilize information from preceding words or context, and could explain the increased N400 to the congruent or related words recently reported in this disease.
Matsuoka
H
H
Department of Psychiatry, Tohoku University School of Medicine, Sendai, Japan.
Matsumoto
K
K
Yamazaki
H
H
Sakai
H
H
Miwa
S
S
Yoshida
S
S
Numachi
Y
Y
Saito
H
H
Ueno
T
T
Sato
M
M
D000328:Adult; D001921:Brain / Q000502:physiology*; D005074:Evoked Potentials, Visual; D005260:Female; D006801:Humans; D008297:Male; D012559:Schizophrenia / Q000175:diagnosis*; D013997:Time Factors; D014825:Vocabulary