Harunobu Ando

Exploratory eye movements in schizophrenic patients and patients with frontal lobe lesions

SummaryExploratory eye movements in 20 schizophrenics, 18 patients with frontal lobe lesions (9 right-sided and 9 left-sided) and 20 normal controls were examined with an eye mark recorder while they viewed stationary S-shaped figures. The eye movements made during the subjects first 15-s viewing of an original figure were analyzed. Patients with right frontal lobe lesions (RF) and schizophrenics (S) had lower scores than normal controls (NC) for the number of eye fixations, total eye scanning length and mean eye scanning length. Each subject was then shown two other figures slightly different from the original and was requested to compare them with the original. After comparing them, the subject wastasked the question, “Are there any other differences?” The eye movements made over the ensuing 5 s in response to this question were scored using the responsive search score (RSS). The RSS was low only in the S group. The subject was also asked to reproduce the original figure before and after making comparisons between the figures. The RF and S groups were poorer at reproduction than the NC group. These findings suggest that there is disordered function of the right frontal lobe in sehizophrenia, and that schizophrenia is due not only to localized damage to one part of the brain but to more widespread damage.

Exploratory eye movement dysfunctions in patients with schizophrenia: possibility as a discriminator for schizophrenia

In our previous studies patients with schizophrenia and their parents had less frequent eye fixations and a more limited area of inspection than normal controls while freely viewing stationary S-shaped figures. The present study attempted to discriminate schizophrenics from non-schizophrenics using exploratory eye movements. Two groups (A and B) were formed, each comprising 30 schizophrenic and 70 non-schizophrenic subjects (10 each of patients with depression, methamphetamine psychosis, alcohol psychosis, anxiety disorder, temporal lobe epilepsy, frontal lobe lesions and healthy normal controls). Discriminant analysis was performed on group A to obtain a discriminant. The validity of applying this discriminant to group B was investigated. By focussing on exploratory eye movements, schizophrenics could be discriminated from non-schizophrenics with a sensitivity of 76.7% and a specificity of 81.4%. These results show that exploratory eye movements are a useful discriminator for schizophrenia.

Exploratory eye movements during the Benton Visual Retention Test: Characteristics of visual behavior in schizophrenia

Abstract In order to investigate the relationship between the behavioral patterns and clinical symptomatology in schizophrenia, exploratory eye movements of schizophrenic subjects and healthy controls during the Benton Visual Retention Test were examined using an eye‐mark recorder. The results were as follows: (i) with card 1, the number of eye fixations of schizophrenic subjects was fewer, and the total and mean eye scanning lengths of schizophrenic subjects were shorter than those of healthy controls; (ii) with card 3, almost none of the schizophrenic subjects looked at the blank area opposite the peripheral figure on the right; (iii) with cards 3, 5, 6 and 9 there were some schizophrenic subjects who did not look at the peripheral figures; (iv) with card 6, many of the schizophrenic subjects made stereotypical movements; (v) with card 9, schizophrenic subjects used a narrow vertical gaze to look at the large figure on the right. Based on these characteristics among the schizophrenic subjects themselves, factors such as longer eye scanning length, looking at peripheral figures without fail, and not making stereotypical movements were reflected directly in the results of the Benton test, while there was no relationship between the width of the vertical gaze and the Benton results. Correlations between visual behavior and some psychiatric symptoms were observed. The visual behavioral patterns of schizophrenic subjects were various according to the characteristics of the Benton figures, while those of normal subjects were always almost the same. It was suggested that these results were caused by disturbances of the mental attitude of schizophrenic subjects toward objects or environments.

Eye Movement as an Indicator of Brain Function

Abstract: The level of consciousness between the alert and drowsy states was classified into four stages (Alert, Resting I, Resting II, Drowsy) by studying three factors of the EEG patterns on 23 normal subjects. The eye movements recorded by electro‐oculograph were divided into two groups, i.e. rapid eye movements (R type, r type) and slow eye movements (S type, s type). The occurrence of each type of eye movements was confirmed to change in close correspondence to the stages of consciousness.

Discriminant Analysis Between Schizophrenics and Nonschizophrenics Using Exploratory Eye Movements

To extract a common feature from schizophrenics, we discriminated schizophrenics from nonschizophrenics using exploratory eye movements. Eye movements while viewing a stationary figure were recorded using an eye-mark recorder. Subjects were 60 schizophrenics and 140 nonschizophrenics, consisting of six patient groups with various psychiatric diseases and normal controls. Of five indicators of eye movements available, the responsive search score (RSS), which is eye movements in response to repeated questions in a comparison task and number of eye fixations (NEF) in memory tasks, were selected by stepwise selection. The schizophrenics were discriminated from nonschizophrenics with a sensitivity of 73.3%–76.7% and a specificity of 81.4%–84.3%. The obtained discriminated function in this study was applied to the data of a WHO collaborative project including 167 schizophrenics, 144 depressed patients, and 154 normal subjects in six countries. In total, the sensitivity was 88% and specificity was 83.9%. It was found that we could extract a common feature from many schizophrenics using the RSS and NEF of exploratory eye movements.

Eye Movements during Perception of Pictures in Schizophrenics

When two areas of both hemispheres are in active, functional communication with each other, EEG coupling may exist between the two areas. We studied the degree and direction of such EEG coupling using the “entropy analysis” method. This method gives a measure of correlation between mutually coupled time series and distinguishes the direction of information flow for the time series. During the linguistic process, the dominant direction of interhemispheric EEG coupling was found from Wernicke’s area to its counterpart area of the opposite (right) hemisphere.’ During voluntary movements (opposing thumb movements with the right hand alone, left alone and both simultaneously), the dominant direction of EEG coupling between the homologous central areas of both hemispheres was dependent on the side of the moving thumb.* Further, alpha activity at rest was found to spread predominantly in the direction of the anterior to posterior regions. No dominant direction between the hemispheres was observed.:’ From these findings, the significance of directional EEG interactions among the different areas is discussed.