[Eye movements in schizophrenia--relationships among eye movements under three experimental conditions; closed-eye, pursuit, and exploratory].

In order to investigate the pathophysiology of schizophrenia using psychophysiological indicators of eye movements, this study was conducted to clarify relations among eye movements under three experimental conditions; closed-eye, pursuit, and exploratory eye movements. Thirty-five chronic schizophrenic patients diagnosed by DSM-III-R criteria and 32 normal controls were examined. Horizontal eye movements were recorded electrooculographically with the subjects under two experimental conditions; one with eyes closed ("Closed-eye Eye Movement," Closed-eye EM), and the other with visually tracking a moving pendulum ("Pursuit Eye Movement," Pursuit EM). The closed-eye condition was further divided into two sub-conditions; one with the subjects awake and at rest, and the other with the subjects in the presence of a repetitive sound. Exploratory eye movements were recorded with an eye-mark recording system while the subjects viewing "S"-shaped geometric figures ("Exploratory Eye Movement," Exploratory EM). Indicators of eye movements under the three experimental conditions described above were measured and the correlations among them were investigated. Clinical symptoms in schizophrenics were assessed by BPRS, SANS and SADS and studied with the Factor Analysis method. In the Closed-eye EM, rapid eye movements appeared significantly more frequently and slow ones were less frequent in schizophrenics than in normals under both sub-conditions. The results for schizophrenics did not change significantly with the addition of sound stimuli. In the Pursuit EM, both the number and amplitude ratio of saccades were significantly larger in schizophrenics than in normals, although these indicators gradually decreased in both groups when tasks requiring concentration were demanded. In the Exploratory EM, the number of eye fixations, the total eye scanning length, and the "Responsive Search Score (RSS)," which is the total number of sections on which the eyes fixed during the response to the confirmative question, were all significantly smaller in schizophrenics than in normals. In schizophrenics, there were significant negative correlations between the RSS of the Exploratory EM and the number of rapid eye movements of the Closed-eye EM, the RSS and the number, amplitude ratio of saccades of the Pursuit EM, respectively. On the contrary, in normals, significant positive correlations were found between the number of rapid eye movements and the number of saccades.(ABSTRACT TRUNCATED AT 250 WORDS)