Die Fledermaus: regarding optokinetic contrast sensitivity and light-adaptation, chicks are mice with wings

PLoS One. 2013 Sep 30;8(9):e75375. doi: 10.1371/journal.pone.0075375. eCollection 2013.


Background: Through adaptation, animals can function visually under an extremely broad range of light intensities. Light adaptation starts in the retina, through shifts in photoreceptor sensitivity and kinetics plus modulation of visual processing in retinal circuits. Although considerable research has been conducted on retinal adaptation in nocturnal species with rod-dominated retinas, such as the mouse, little is known about how cone-dominated avian retinas adapt to changes in mean light intensity.

Methodology/principal findings: We used the optokinetic response to characterize contrast sensitivity (CS) in the chick retina as a function of spatial frequency and temporal frequency at different mean light intensities. We found that: 1) daytime, cone-driven CS was tuned to spatial frequency; 2) nighttime, presumably rod-driven CS was tuned to temporal frequency and spatial frequency; 3) daytime, presumably cone-driven CS at threshold intensity was invariant with temporal and spatial frequency; and 4) daytime photopic CS was invariant with clock time.

Conclusion/significance: Light- and dark-adaptational changes in CS were investigated comprehensively for the first time in the cone-dominated retina of an avian, diurnal species. The chick retina, like the mouse retina, adapts by using a "day/night" or "cone/rod" switch in tuning preference during changes in lighting conditions. The chick optokinetic response is an attractive model for noninvasive, behavioral studies of adaptation in retinal circuitry in health and disease.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptation, Ocular / physiology*
  • Analysis of Variance
  • Animals
  • Chickens
  • Circadian Rhythm / physiology
  • Contrast Sensitivity / physiology*
  • Light*
  • Nystagmus, Optokinetic / physiology*
  • Retinal Cone Photoreceptor Cells / physiology*
  • Retinal Cone Photoreceptor Cells / radiation effects
  • Species Specificity

Grants and funding

This work was supported by (1) Natural Sciences and Engineering Research Coouncil of Canada (NSERC), #RGPIN 131-2013, “Retinal Control of Eye Growth and Myopia”, W.K. Stell, PI. (2) FFB (Foundation Fighting Blindness of Canada)-EYEGEYE Research Training Fund, W.K. Stell, PI. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.