title: Receptive field asymmetries produce color-dependent direction selectivity in primate lateral geniculate nucleus.
abstract: Blue-on receptive fields recorded in primate retina and lateral geniculate nucleus are customarily described as showing overlapping blue-on and yellow-off receptive field components. However, the retinal pathways feeding the blue-on and yellow-off subfields arise from spatially discrete receptor populations, and recent studies have given contradictory accounts of receptive field structure of blue-on cells. Here we analyzed responses of blue-on cells to drifting gratings, in single-cell extracellular recordings from the dorsal lateral geniculate nucleus in marmosets. We show that most blue-on cells exhibit selectivity for the drift direction of achromatic gratings. The standard concentric difference-of-Gaussians (DOG) model thus cannot account for responses of these cells. We apply a simple, anatomically plausible, extension of the DOG model. The model incorporates temporally offset elliptical two-dimensional Gaussian subfields. The model can predict color-contingent direction and spatial tuning. Because direction tuning in blue-on cells depends on stimulus chromaticity, spatial frequency, and temporal frequency, this property is of little value as a general mechanism for image movement detection. It is possible that anatomical wiring for color selectivity has constrained the capacity of blue-on cells to contribute to spatial and motion vision.
authors.affiliation: Save Sight Institute and ARC Centre of Excellence in Vision Science, University of Sydney, Sydney, NSW, Australia. ctailby@unimelb.edu.au
authors.forename: Chris
authors.initials: C
authors.lastname: Tailby
authors.forename: William J
authors.initials: WJ
authors.lastname: Dobbie
authors.forename: Samuel G
authors.initials: SG
authors.lastname: Solomon
authors.forename: Brett A
authors.initials: BA
authors.lastname: Szmajda
authors.forename: Maziar
authors.initials: M
authors.lastname: Hashemi-Nezhad
authors.forename: Jason D
authors.initials: JD
authors.lastname: Forte
authors.forename: Paul R
authors.initials: PR
authors.lastname: Martin
mesh_terms: D000200:Action Potentials / Q000502:physiology*; D000818:Animals; D002144:Callithrix; D003118:Color Perception / Q000502:physiology*; D020647:Lateral Thalamic Nuclei / Q000502:physiology*; D008959:Models, Neurological; D009474:Neurons / Q000502:physiology; D010775:Photic Stimulation; D012165:Retinal Ganglion Cells / Q000502:physiology*; D014794:Visual Fields / Q000502:physiology*