Variability in the decision process leading to saccades: A specific marker for schizophrenia?

Authors

  • Christos Theleritis,

    1. Laboratory of Sensorimotor Control, University Mental Health Research Institute, Athens, Greece
    2. Psychiatry Department, National and Kapodistrian University of Athens, Eginition Hospital, Athens, Greece
    3. Department of Psychosis Studies, Institute of Psychiatry, King's College London, London, UK
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  • Ioannis Evdokimidis,

    1. Neurology Department, National and Kapodistrian University of Athens, Eginition Hospital, Athens, Greece
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  • Nikolaos Smyrnis

    Corresponding author
    1. Laboratory of Sensorimotor Control, University Mental Health Research Institute, Athens, Greece
    2. Psychiatry Department, National and Kapodistrian University of Athens, Eginition Hospital, Athens, Greece
    • Address correspondence to: Nikolaos Smyrnis, Laboratory of Sensorimotor Control, University Mental Health Research Institute (UMHRI), 2 Soranou Efesiou Street, Athens 11527, Greece. E-mail: smyrnis@med.uoa.gr

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  • The collection of the ASPIS data was supported by the grant EKBAN 97 to Professor C. N. Stefanis from the General Secretariat of Research and Technology of the Greek Ministry of Development. We would like to thank Professor Roger H. S. Carpenter for providing us with the analysis software for the LATER model and for his advice on the specific analysis of the data.

Abstract

In a previous study, deviance in the reaction time (RT) distribution of saccades for patients with schizophrenia was explained using an oculomotor decision model. Here, RTs of visually guided saccades in young healthy men, healthy children, older adults, patients with schizophrenia, and patients with obsessive compulsive disorder (OCD) were modeled to study the specificity of this decision process deviance for schizophrenia. The mean decision rate to saccade decreased with age in children and increased in older adults while the decision rate intrasubject variability (ISV) was not modulated by age. A significant increase in ISV of the decision rate was confirmed for patients with schizophrenia but not OCD compared to healthy controls. There was no effect of medication on model parameters in the OCD patient group. These results confirm the specificity of the deviance in a simple oculomotor decision process in schizophrenia.

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