HUMAN OCULOMOTOR FUNCTION - RELIABILITY AND DIURNAL-VARIATION

To provide information on test-retest reliability for seven oculomotor paradigms currently used in studies of schizophrenia and other neurop sychiatric conditions, we tested eight controls at four weekly interva ls, twice in the morning (8-10 AM) and twice in the afternoon (3-5 PM) , Intraclass correlation coefficients were significant (p < .05) for b oth AM and PM pairs of measures as well as for mean AM and PM pairs fo r closed-loop pursuit gain, open-loop pursuit gain (using velocity as the measure), saccadic frequency during pursuit and fixation, visually and nonvisually guided saccadic latency and velocity, antisaccadic la tency, and premature reflexive saccades during the memory-guided sacca de task. Acceleration as a measure of open-loop gain (for slower targe ts) and accuracy of saccades to a moving target were only reliable at PM testing time. Nonvisually guided saccadic accuracy and inappropriat e reflexive saccades during the antisaccade task were not reliable, po ssibly due to the narrow range of values for these measures. Except fo r approximately 10% fewer saccades during pursuit and fixation in the morning, there were no consistent diurnal differences, These findings suggest that, in a small sample of subjects, most measures of oculomot or function are stable across time and may reflect underlying neurophy siologic traits.