Mixture analysis of smooth pursuit eye movements in schizophrenia

Authors

  • DAVID E. ROSS,

    Corresponding author
    1. Department of Psychiatry, Medical College of Virginia — Virginia Commonwealth University, Richmond, USA
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  • ALFRED L. OCHS,

    1. Department of Biomedical Engineering, Medical Colleg — Virginia Commonwealth University, Richmond, USA
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  • ANAND K. PANDURANGI,

    1. Department of Psychiatry, Medical College of Virginia — Virginia Commonwealth University, Richmond, USA
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  • LEROY R. THACKER,

    1. Department of Psychiatry, Medical College of Virginia — Virginia Commonwealth University, Richmond, USA
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  • KENNETH S. KENDLER

    1. Department of Psychiatry, Medical College of Virginia — Virginia Commonwealth University, Richmond, USA
    2. Department of Human Genetics, Medical College of Virginia — Virginia Commonwealth University, Richmond, USA
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  • We thank Deborah Medoff, Gunvant Thaker, and Marianne Moran for their assistance with statistical methods, and Ann Gorman, Kathy Davis, and Mark Wilson for their assistance in analysis of the data.

Address reprint requests to: Dr. David Ross, P.O. Box 21247, Maryland Psychiatric Research Center, University of Maryland at Baltimore, Baltimore, MD 21228, USA E-mail: davideross@aol.com.

Abstract

The goal of this study was to replicate and extend previous findings indicating that the eye movement data of schizophrenic patients is best represented by the mixture of two groups, one of which has distinctly poor performance. Forty-nine schizophrenic patients and 32 normal controls had their smooth pursuit eye movements quantified by calculating the root mean square (RMS) deviation between the target and eye waveforms. Based on the finding of mixture in the distribution of RMS error, the patients were divided in to low (better tracking) and high (worse tracking) RMS error subgroups. The high RMS error patient had abnormally decreased gain. Both patient subgroups had abnormally increased frequency of catch-up saccades and increased phase lag. Distinguishing between these two subgroups may be useful in clarifying the pathophysiology of abnormal pursuit and its relationship to heterogeneity in schizophrenia.

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