title: Amplitude criteria and anticipatory saccades during smooth pursuit eye movements in schizophrenia.
abstract: Increased frequency of anticipatory saccades during smooth pursuit eye movements is a potential marker of genetic risk for schizophrenia even in the absence of clinical symptomology. The operational definition of anticipatory saccades has often included an amplitude criterion; however, these amplitude criteria have often differed across studies. This study reports on the effect of varying amplitude criteria on the effect size in a comparison of 29 schizophrenic adults and 29 normal subjects during a 16.7 degrees/s constant velocity task. The inclusion of small amplitude anticipatory saccades, with amplitudes of 1-4 degrees, consistently increased effect size (largest effect size = 1.61). The inclusion of large anticipatory saccades, with amplitudes of 4 degrees or greater, had an inconsistent impact on effect size. The separation of anticipatory saccades into leading saccades (anticipatory saccades with amplitude 1-4 degrees) and large anticipatory saccades (amplitude > 4 degrees) deserves further exploration.
authors.affiliation: Department of Psychiatry, University of Colorado Health Sciences Center, Denver, USA. randy.ross@uchsc.edu
authors.forename: R G
authors.initials: RG
authors.lastname: Ross
authors.forename: A
authors.initials: A
authors.lastname: Olincy
authors.forename: A
authors.initials: A
authors.lastname: Radant
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D016009:Chi-Square Distribution; D005260:Female; D005819:Genetic Markers; D006801:Humans; D008297:Male; D011237:Predictive Value of Tests; D011601:Psychophysics; D011698:Pursuit, Smooth / Q000502:physiology*; D012016:Reference Values; D012438:Saccades / Q000502:physiology*; D012559:Schizophrenia / Q000235:genetics / Q000503:physiopathology*
chemical_list: D005819:Genetic Markers