Processing of single-photon responses in the mammalian on and off retinal pathways at the sensitivity limit of vision

Daisuke Takeshita, Lina Smeds, Petri Ala-Laurila*

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

9 Citations (Scopus)
100 Downloads (Pure)

Abstract

Visually guided behaviour at its sensitivity limit relies on single-photon responses originating in a small number of rod photoreceptors. For decades, researchers have debated the neural mechanisms and noise sources that underlie this striking sensitivity. To address this question, we need to understand the constraints arising from the retinal output signals provided by distinct retinal ganglion cell types. It has recently been shown in the primate retina that On and Off parasol ganglion cells, the cell types likely to underlie light detection at the absolute visual threshold, differ fundamentally not only in response polarity, but also in the way they handle single-photon responses originating in rods. The On pathway provides the brain with a thresholded, low-noise readout and the Off pathway with a noisy, linear readout. We outline the mechanistic basis of these different coding strategies and analyse their implications for detecting the weakest light signals. We show that high-fidelity, nonlinear signal processing in the On pathway comes with costs: more single-photon responses are lost and their propagation is delayed compared with the Off pathway. On the other hand, the responses of On ganglion cells allow better intensity discrimination compared with the Off ganglion cell responses near visual threshold.

Original languageEnglish
Article number20160073
Pages (from-to)1-10
JournalPHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY B: BIOLOGICAL SCIENCES
Volume372
Issue number1717
DOIs
Publication statusPublished - 5 Apr 2017
MoE publication typeA1 Journal article-refereed

Keywords

  • Linear and nonlinear signal processing
  • On and off retinal ganglion cells
  • Physical limits
  • Scotopic vision
  • Visual sensitivity
  • Visual threshold

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