title: Orientation-tuned surround suppression in mouse visual cortex.
abstract: The firing rates of neurons in primary visual cortex (V1) are suppressed by large stimuli, an effect known as surround suppression. In cats and monkeys, the strength of suppression is sensitive to orientation; responses to regions containing uniform orientations are more suppressed than those containing orientation contrast. This effect is thought to be important for scene segmentation, but the underlying neural mechanisms are poorly understood. We asked whether it is possible to study these mechanisms in the visual cortex of mice, because of recent advances in technology for studying the cortical circuitry in mice. It is unknown whether neurons in mouse V1 are sensitive to orientation contrast. We measured the orientation selectivity of surround suppression in the different layers of mouse V1. We found strong surround suppression in layer 4 and the superficial layers, part of which was orientation tuned: iso-oriented surrounds caused more suppression than cross-oriented surrounds. Surround suppression was delayed relative to the visual response and orientation-tuned suppression was delayed further, suggesting two separate suppressive mechanisms. Previous studies proposed that surround suppression depends on the activity of inhibitory somatostatin-positive interneurons in the superficial layers. To test the involvement of the superficial layers we topically applied lidocaine. Silencing of the superficial layers did not prevent orientation-tuned suppression in layer 4. These results show that neurons in mouse V1, which lacks orientation columns, show orientation-dependent surround suppression in layer 4 and the superficial layers and that surround suppression in layer 4 does not require contributions from neurons in the superficial layers.
authors.affiliation: Department of Vision and Cognition, m.self@nin.knaw.nl.
authors.forename: Matthew W
authors.initials: MW
authors.lastname: Self
authors.affiliation: Department of Vision and Cognition.
authors.forename: Jeannette A M
authors.initials: JA
authors.lastname: Lorteije
authors.affiliation: Department of Vision and Cognition.
authors.forename: Joris
authors.initials: J
authors.lastname: Vangeneugden
authors.affiliation: Department of Vision and Cognition.
authors.forename: Enny H
authors.initials: EH
authors.lastname: van Beest
authors.affiliation: Department of Vision and Cognition.
authors.forename: Mihaela E
authors.initials: ME
authors.lastname: Grigore
authors.affiliation: Department of Molecular Visual Plasticity, and.
authors.forename: Christiaan N
authors.initials: CN
authors.lastname: Levelt
authors.affiliation: Department of Cortical Structure and Function, Netherlands Institute for Neuroscience, 1105 BA, Amsterdam, the Netherlands.
authors.forename: J Alexander
authors.initials: JA
authors.lastname: Heimel
authors.affiliation: Department of Vision and Cognition, Department of Integrative Neurophysiology, Center for Neurogenomics and Cognitive Research, VU University, 1081 HV Amsterdam, the Netherlands, and Psychiatry Department, Academic Medical Center, 1100 DD Amsterdam, the Netherlands.
authors.forename: Pieter R
authors.identifier: http://orcid.org/0000-0002-1625-0034
authors.initials: PR
authors.lastname: Roelfsema
mesh_terms: D000818:Animals; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009415:Nerve Net / Q000502:physiology*; D009433:Neural Inhibition / Q000502:physiology*; D009949:Orientation / Q000502:physiology*; D010775:Photic Stimulation / Q000379:methods; D013028:Space Perception / Q000502:physiology*; D014793:Visual Cortex / Q000502:physiology*; D014794:Visual Fields / Q000502:physiology*; D014796:Visual Perception / Q000502:physiology*
keywords: V1; laminar; mouse visual cortex; orientation; scene segmentation; surround suppression