title: Visual-Motor Transformations Within Frontal Eye Fields During Head-Unrestrained Gaze Shifts in the Monkey.
abstract: A fundamental question in sensorimotor control concerns the transformation of spatial signals from the retina into eye and head motor commands required for accurate gaze shifts. Here, we investigated these transformations by identifying the spatial codes embedded in visually evoked and movement-related responses in the frontal eye fields (FEFs) during head-unrestrained gaze shifts. Monkeys made delayed gaze shifts to the remembered location of briefly presented visual stimuli, with delay serving to dissociate visual and movement responses. A statistical analysis of nonparametric model fits to response field data from 57 neurons (38 with visual and 49 with movement activities) eliminated most effector-specific, head-fixed, and space-fixed models, but confirmed the dominance of eye-centered codes observed in head-restrained studies. More importantly, the visual response encoded target location, whereas the movement response mainly encoded the final position of the imminent gaze shift (including gaze errors). This spatiotemporal distinction between target and gaze coding was present not only at the population level, but even at the single-cell level. We propose that an imperfect visual-motor transformation occurs during the brief memory interval between perception and action, and further transformations from the FEF's eye-centered gaze motor code to effector-specific codes in motor frames occur downstream in the subcortical areas.
authors.affiliation: Centre for Vision Research Canadian Action and Perception Network (CAPnet) Neuroscience Graduate Diploma Program Department of Biology.
authors.forename: Amirsaman
authors.initials: A
authors.lastname: Sajad
authors.affiliation: Centre for Vision Research Canadian Action and Perception Network (CAPnet) Neuroscience Graduate Diploma Program School of Kinesiology and Health Sciences.
authors.forename: Morteza
authors.initials: M
authors.lastname: Sadeh
authors.affiliation: Centre for Vision Research Canadian Action and Perception Network (CAPnet) Department of Psychology, York University, Toronto, ON, Canada M3J 1P3.
authors.forename: Gerald P
authors.initials: GP
authors.lastname: Keith
authors.affiliation: Centre for Vision Research Canadian Action and Perception Network (CAPnet).
authors.forename: Xiaogang
authors.initials: X
authors.lastname: Yan
authors.affiliation: Centre for Vision Research Canadian Action and Perception Network (CAPnet).
authors.forename: Hongying
authors.initials: H
authors.lastname: Wang
authors.affiliation: Centre for Vision Research Canadian Action and Perception Network (CAPnet) Neuroscience Graduate Diploma Program Department of Biology School of Kinesiology and Health Sciences Department of Psychology, York University, Toronto, ON, Canada M3J 1P3.
authors.forename: John Douglas
authors.initials: JD
authors.lastname: Crawford
mesh_terms: D000200:Action Potentials; D000818:Animals; D005260:Female; D005625:Frontal Lobe / Q000502:physiology*; D006257:Head / Q000502:physiology*; D008253:Macaca mulatta; D009474:Neurons / Q000502:physiology*; D011597:Psychomotor Performance / Q000502:physiology*; D012438:Saccades; D014796:Visual Perception / Q000502:physiology*
keywords: eye–head coordination; frontal eye field; gaze control; sensorimotor transformation; spatial coding