|Budget Amount *help
¥2,600,000 (Direct Cost: ¥2,600,000)
Fiscal Year 2002: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 2001: ¥2,100,000 (Direct Cost: ¥2,100,000)
Background: Certain neuropsychiatric diseases are characterized, or even presaged, by disturbances in sleep-wake control and arousal, functions of the reticular activating system (RAS). One measure of RAS function is the P50 midlatency auditory evoked potential. Using a paired stimulus paradigm, the amplitude of the first response is a measure of the initial responsiveness of the system, while the ratio of the two responses at a short interstimulus interval is a measure of sensory gating. Methods: Sensory gating [(P50_<S2>/P50_<S1>)X100 (%)] was obtained from schizophrenics (n=27) and healthy volunteers (n=27). In addition, Positive and Negative Syndrome Scale (PANSS) and Schizotypal Personality Questionnaire (SPQ) were administered to schizophrenics and healthy volunteers, respectively. Results: (i) P50 sensory gating in schizophrenics (84.4±58.3) differed significantly (p<0.001) from that in normal subjects (20.9±20.1). (ii) In schizophrenics, P50 sensory gating did not correlate with any PANSS score. (iii) In healthy volunteers, sensory gating had significant correlation with both total SPQ scores (r=0.525, p=0.001) and withdrawn factor scores (r=0.486, p=0.004). (iv) When normal subjects were divided into low (<12) and high (≧13) SPQ score groups, sensory gating in high SPQ score group was significantly higher (poorer) than that in low SPQ score group (Z=3.40, p=0.001). Conclusions: Consistent with the previous reports, P50 gating deficits were demonstrated in schizophrenic patients. In normal subjects, schizotypical traits, specifically withdrawn aspects of schizotypy, appeared to be related to poorer sensory gating. This findings may support the view that poor P50 sensory gating in schizophrenia is related to symptomatology.