Disturbed eye movements guided by visuospatial cues in schizophrenic patients

Visually guided exploration in Huntington disease

We compared 24 patients in various stages of Huntington disease (HD) with 26 control patients free from cerebral disorders using a simple visual saccadic tracking test. The two groups were well matched in regard to age, sex, verbal IQ and years of schooling. Test results differed widely. On a time versus error plot, sensitivity (96%) and specificity (100%) were high and the results did not depend on age, education, or disease duration, although an influence of disease stage could be observed. This study shows that a simple saccadic tracking task may be useful in detecting visuomotor disturbances in HD.

Saccadic eye movements and regional cerebral blood flow in schizophrenic patients

This study examined saccadic eye movements, using simple stationary targets, in schizophrenic patients. The targets were eight black points or eight arabic-numbered points placed in randomized order on the circumference of a circle. Self-paced eye movements during clockwise tracking of these points, by 23 patients and 23 controls, were recorded using an infrared eye-mark recorder. Then the relationship between the saccades and clinical symptoms was investigated. Finally, the relationship between the performance of the saccades and resting regional cerebral blood flow (rCBF) was examined using single photon emission computed tomography with 99mTc-hexamethyl propyleneamine oxime (HMPAO). The results indicate that patients track with significantly fewer correct scores and more deviant scores than controls, in agreement with our previous study. There were two groups of patients: an ordinary group who obtained a full-target-hitting score at a 200-ms setting and a fast group who obtained the full score at 100 ms but not at 200 ms. Some patients displayed significantly more hypermetria than controls. Significant correlations were found between hallucination and delusion symptoms and correct score. With respect to relative rCBF, fast-group patients showed significantly decreased rCBF in the left limbic and inferior parietal areas as compared with ordinary group patients. These findings suggest that some schizophrenic patients view the stationary targets too fast and this may be related to dysfunction in the limbic-parietal association area in the left hemisphere.

Saccadic tracking test--normal data and reliability

A saccadic tracking test, which involves the scanning of a path guided by the direction of a sequence of arrows, was administered to 102 healthy control subjects. The data show a gender effect and a slight age and education effect. The internal consistency--estimated by Cronbach's alpha--was high, .94. The test promises to be a sensitive estimator of the capacity of a subject to explore a visual display, a skill necessary for a wide range of other test performances.

Impaired saccadic eye movements on stationary targets in patients with schizophrenia spectrum disorder

This study examined tracking eye movements on predetermined stationary targets in patients with schizophrenia spectrum disorder. The targets were 8 black points or 8 arabic-numbered points placed on the circumference of a circle. Self-paced eye movements during clockwise tracking of these points by 23 patients and 23 normal controls were recorded using an infrared eye-mark recorder. Eye movements were analyzed at two settings: firstly, when "fixation point" was defined as a point at which a gaze was held for at least 200-ms; and secondly, when held for at least 100-ms. The results indicated that at the 200-ms setting schizophrenic patients track with significantly fewer correct scores and more deviant scores than controls under black-point conditions. At the 100-ms setting, however, the correct scores of patients were not significantly different from those of controls, although patients displayed more aberrant paths than controls. The superfluous fixations in the patients improved significantly under numbered-point conditions, but patients still achieved lower correct scores than controls. Four of the 23 patients exhibited centering (aberrant path directed toward the center point), suggesting immature control of eye movements under black-point conditions, but not numbered-point conditions. These results suggest that some schizophrenic patients viewed the targets too quickly, and that they have impaired directed attention, which can be improved by cues, and may have impaired preprogramming of eye movements, which is not improved by external cues.

Impaired performance in a saccadic tracking task in schizophrenic patients

The performance of schizophrenic patients in a task which requires a sequence of saccades guided by visuospatial cues is reported. A previous study recording eye movements determined a highly increased number of fixations necessary for this task in acute schizophrenic patients compared with normal controls. The performance of normal control subjects of different age groups and the correlation between the performance in the tracking task and the results of a clinical psychological test battery are described. Schizophrenic patients in a partly remitted state and in a remitted or mildly chronic state performed this task worse than matched control subjects; this was particularly indicated by the time score. The relation to the lifetime dosage of neuroleptic medication is considered.