title: Cross-species comparison of anticipatory and stimulus-driven neck muscle activity well before saccadic gaze shifts in humans and nonhuman primates.
abstract: Recent studies have described a phenomenon wherein the onset of a peripheral visual stimulus elicits short-latency (<100 ms) stimulus-locked recruitment (SLR) of neck muscles in nonhuman primates (NHPs), well before any saccadic gaze shift. The SLR is thought to arise from visual responses within the intermediate layers of the superior colliculus (SCi), hence neck muscle recordings may reflect presaccadic activity within the SCi, even in humans. We obtained bilateral intramuscular recordings from splenius capitis (SPL, an ipsilateral head-turning muscle) from 28 human subjects performing leftward or rightward visually guided eye-head gaze shifts. Evidence of an SLR was obtained in 16/55 (29%) of samples; we also observed examples where the SLR was present only unilaterally. We compared these human results with those recorded from a sample of eight NHPs from which recordings of both SPL and deeper suboccipital muscles were available. Using the same criteria, evidence of an SLR was obtained in 8/14 (57%) of SPL recordings, but in 26/29 (90%) of recordings from suboccipital muscles. Thus, both species-specific and muscle-specific factors contribute to the low SLR prevalence in human SPL. Regardless of the presence of the SLR, neck muscle activity in both human SPL and in NHPs became predictive of the reaction time of the ensuing saccade gaze shift ∼70 ms after target appearance; such pregaze recruitment likely reflects developing SCi activity, even if the tectoreticulospinal pathway does not reliably relay visually related activity to SPL in humans.
authors.affiliation: Department of Physiology & Pharmacology, University of Western Ontario, London, Ontario, Canada;
authors.forename: Samanthi C
authors.initials: SC
authors.lastname: Goonetilleke
authors.affiliation: Center for Perceptual Systems and Institute for Neuroscience, The University of Texas at Austin, Austin, Texas;
authors.forename: Leor
authors.initials: L
authors.lastname: Katz
authors.affiliation: Department of Neurobiology, Northwestern University, Evanston, Illinois;
authors.forename: Daniel K
authors.identifier: http://orcid.org/0000-0002-3179-4072
authors.initials: DK
authors.lastname: Wood
authors.affiliation: Department of Psychology, University of Western Ontario, London, Ontario, Canada; Brain and Mind Institute, University of Western Ontario, London, Ontario, Canada; and.
authors.forename: Chao
authors.initials: C
authors.lastname: Gu
authors.affiliation: Center for Perceptual Systems and Institute for Neuroscience, The University of Texas at Austin, Austin, Texas;
authors.forename: Alexander C
authors.initials: AC
authors.lastname: Huk
authors.affiliation: Department of Physiology & Pharmacology, University of Western Ontario, London, Ontario, Canada; Department of Psychology, University of Western Ontario, London, Ontario, Canada; Brain and Mind Institute, University of Western Ontario, London, Ontario, Canada; and Robarts Research Institute, London, Ontario, Canada bcorneil@uwo.ca.
authors.forename: Brian D
authors.initials: BD
authors.lastname: Corneil
mesh_terms: D000328:Adult; D000818:Animals; D059031:Anticipation, Psychological / Q000502:physiology*; D004576:Electromyography; D005260:Female; D006801:Humans; D008252:Macaca fascicularis; D008253:Macaca mulatta; D008297:Male; D009043:Motor Activity / Q000502:physiology*; D009334:Neck Muscles / Q000502:physiology*; D009483:Neuropsychological Tests; D010775:Photic Stimulation; D012438:Saccades / Q000502:physiology*; D013045:Species Specificity
keywords: eye-head coordination; neck electromyogram; oculomotor; saccades