title: Characteristics of Spontaneous Square-Wave Jerks in the Healthy Macaque Monkey during Visual Fixation.
abstract: Saccadic intrusions (SIs), predominantly horizontal saccades that interrupt accurate fixation, include square-wave jerks (SWJs; the most common type of SI), which consist of an initial saccade away from the fixation target followed, after a short delay, by a return saccade that brings the eye back onto target. SWJs are present in most human subjects, but are prominent by their increased frequency and size in certain parkinsonian disorders and in recessive, hereditary spinocerebellar ataxias. SWJs have been also documented in monkeys with tectal and cerebellar etiologies, but no studies to date have investigated the occurrence of SWJs in healthy nonhuman primates. Here we set out to determine the characteristics of SWJs in healthy rhesus macaques (Macaca mulatta) during attempted fixation of a small visual target. Our results indicate that SWJs are common in healthy nonhuman primates. We moreover found primate SWJs to share many characteristics with human SWJs, including the relationship between the size of a saccade and its likelihood to be part of a SWJ. One main discrepancy between monkey and human SWJs was that monkey SWJs tended to be more vertical than horizontal, whereas human SWJs have a strong horizontal preference. Yet, our combined data indicate that primate and human SWJs play a similar role in fixation correction, suggesting that they share a comparable coupling mechanism at the oculomotor generation level. These findings constrain the potential brain areas and mechanisms underlying the generation of fixational saccades in human and nonhuman primates.
authors.affiliation: Department of Neurobiology, Barrow Neurological Institute, Phoenix, AZ, United States of America; Interdisciplinary Graduate program in Neuroscience, Arizona State University, Tempe, AZ, United States of America.
authors.forename: Francisco M
authors.initials: FM
authors.lastname: Costela
authors.affiliation: Department of Neurobiology, Barrow Neurological Institute, Phoenix, AZ, United States of America; Department of Neurology, Johns Hopkins University, Baltimore, MD, United States of America.
authors.forename: Jorge
authors.initials: J
authors.lastname: Otero-Millan
authors.affiliation: Department of Neurobiology, Barrow Neurological Institute, Phoenix, AZ, United States of America.
authors.forename: Michael B
authors.initials: MB
authors.lastname: McCamy
authors.affiliation: Department of Neurobiology, Barrow Neurological Institute, Phoenix, AZ, United States of America; Department of Ophthalmology, State University of New York Downstate Medical Center, Brooklyn, NY, United States of America.
authors.forename: Stephen L
authors.initials: SL
authors.lastname: Macknik
authors.affiliation: Department of Neurobiology, Barrow Neurological Institute, Phoenix, AZ, United States of America; Mind, Brain and Behavior Research Center; University of Granada, Granada, Spain.
authors.forename: Leandro L
authors.initials: LL
authors.lastname: Di Stasi
authors.affiliation: Department of Neurobiology, Barrow Neurological Institute, Phoenix, AZ, United States of America; Department of Signal Theory and Communications, University of Vigo, Vigo, Spain.
authors.forename: Héctor
authors.initials: H
authors.lastname: Rieiro
authors.affiliation: Veterans Affairs Medical Center, Case Western Reserve University, Cleveland, OH, United States of America.
authors.forename: John R
authors.initials: JR
authors.lastname: Leigh
authors.affiliation: Department of Neurobiology, Barrow Neurological Institute, Phoenix, AZ, United States of America; Unité de Neuroscience, Information et Complexité (CNRS-UNIC), UPR CNRS 3293, Gif-sur-Yvette, France.
authors.forename: Xoana G
authors.initials: XG
authors.lastname: Troncoso
authors.affiliation: Department of Neurobiology, Barrow Neurological Institute, Phoenix, AZ, United States of America.
authors.forename: Ali
authors.initials: A
authors.lastname: Najafian Jazi
authors.affiliation: Department of Neurobiology, Barrow Neurological Institute, Phoenix, AZ, United States of America; Department of Ophthalmology, State University of New York Downstate Medical Center, Brooklyn, NY, United States of America.
authors.forename: Susana
authors.initials: S
authors.lastname: Martinez-Conde
mesh_terms: D000818:Animals; D001921:Brain / Q000502:physiology*; D005403:Fixation, Ocular; D006801:Humans; D008253:Macaca mulatta / Q000502:physiology*; D009043:Motor Activity / Q000502:physiology; D012438:Saccades