Local edge detectors: A substrate for fine spatial vision at low temporal frequencies in rabbit retina

Michiel Van Wyk, William Taylor, David I. Vaney

Research output: Contribution to journalArticle

81 Scopus citations

Abstract

Visual acuity is limited by the size and density of the smallest retinal ganglion cells, which correspond to the midget ganglion cells in primate retina and the β-ganglion cells in cat retina, both of which have concentric receptive fields that respond at either light-On or light-Off. In contrast, the smallest ganglion cells in the rabbit retina are the local edge detectors (LEDs), which respond to spot illumination at both light-On and light-Off. However, the LEDs do not predominate in the rabbit retina and the question arises, what role do they play in fine spatial vision? We studied the morphology and physiology of LEDs in the isolated rabbit retina and examined how their response properties are shaped by the excitatory and inhibitory inputs. Although the LEDs comprise only ∼15% of the ganglion cells, neighboring LEDs are separated by 30-40 μm on the visual streak, which is sufficient to account for the grating acuity of the rabbit. The spatial and temporal receptive-field properties of LEDs are generated by distinct inhibitory mechanisms. The strong inhibitory surround acts presynaptically to suppress both the excitation and the inhibition elicited by center stimulation. The temporal properties, characterized by sluggish onset, sustained firing, and low bandwidth, are mediated by the temporal properties of the bipolar cells and by postsynaptic interactions between the excitatory and inhibitory inputs. We propose that the LEDs signal fine spatial detail during visual fixation, when high temporal frequencies are minimal.

Original languageEnglish (US)
Pages (from-to)13250-13263
Number of pages14
JournalJournal of Neuroscience
Volume26
Issue number51
DOIs
Publication statusPublished - Dec 20 2006

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Keywords

  • Amacrine cell
  • Edge detection
  • Inhibition
  • Rabbit retina
  • Retinal ganglion cell
  • Visual acuity

ASJC Scopus subject areas

  • Neuroscience(all)

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