FUKUDA Masato Univ. of Tokyo, Faculty of Medicine, Lecturer, 医学部(病), 助手
HIRAMATSU Ken-ichi Univ. of Tokyo, Faculty of Medicine, Lecturer, 医学部(病), 助手 (50218814)
ITOH Kenji Univ. of Tokyo, Faculty of Medicine, Lecturer, 医学部, 助手 (80010106)
|Budget Amount *help
¥3,300,000 (Direct Cost: ¥3,300,000)
Fiscal Year 1989: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 1988: ¥2,600,000 (Direct Cost: ¥2,600,000)
Employing the P300 component of ERPs as an electrophysiological index, brain mechanisms involved in successful psychological interventions in schizophrenia were investigated with particular reference to whether their effectiveness of improving schizophrenic cognitive-behavioral deficits is measured through the extent to which P300 amplitudes are augmented.
For this purpose, variations in P300-amplitudes due to psychological manipulating procedures were monitored in a three tone discrimination task which consists of tones at 950.1000, and 1053 Hz in a random sequence with a priori probability of 1/6, 4/6. and 1/6. respectively. In the task, subjects were requested to press a lever upon detection of one of two kinds of infrequent tones.
<< Experiment 1 : P300 to frequent tones ( "frequent P300" )>> Schizophrenic subjects, who are known to fail in demonstrating frequent P300s in contrast to healthy controls, were instructed to perform the task in the following three ways in three different
occasions. These instructions were aimed at facilitating to alter schizophrenics' task-performing strategies into those that healthy controls are speculated to employ. During the task, variations in P300s produced after the instructions were observed.
(1) Via verbal instruction: most schizophrenic subjects showed no P300 change, except one subject who, while performing the task, became aware of the effective strategy by herself that healthy subjects employed. This subject showed a significant P300-amplitude increase after her awareness of the strategy. (2) Via response-mediated training; a significant reduction of P300 was observed. (3) Via target-intensity augmenting method; no significant change was observed.
<<Experiment 2 : P300 to target tones>> To facilitate patients' effectiveness in target detection, a psychological intervention was attempted through delivering a buzzer sound after each designated target tone that informed the just prior tone was the target tone ( "coaching method" ). The smaller P300 group, which showed smaller P300 amplitudes before the coaching method, demonstrated a significant increase in P300 amplitude, whereas the larger P300 group displayed a significant decrease. The smaller P300 group also showed an improvement in the performance level. As for P300 amplitudes to infrequent non-target tones, the smaller P300 group showed no change in the amplitudes: while, the larger P300 group displayed a significant decrease.
The results of Experiment I seem well correlated with our clinical experience in schizophrenic patients: (1) any psychological strategy works most effectively only when noticed by patients; (2) no improvement in task- performance level is obtained through a short-time practice; (3) any intervention not meeting patients rather results in patients' confusion. The results of Experiment 2 indicate the followings: (1) P300 amplitudes in schizophrenics can be altered by psychological intervention to some extent; (2) the direction of P300 amplitude changes are different among patients depending upon their original P300 amplitudes, with the changes being considered specific effects of the intervention; (3) hence, P300 seems a useful index for determination of indication and assessment of efficacy of psychotherapy, behavioral therapy, and cognitive therapy. Less