Spatial resolution, contrast sensitivity, and sensitivity to defocus of chicken retinal ganglion cells in vitro

Abstract

The chicken has been extensively studied as an animal model for myopia because its eye growth is tightly controlled by visual experience. It has been found that the retina controls the axial eye growth rates depending on the amount and the sign of defocus imposed in the projected image. Glucagonergic amacrine cells were discovered that appear to encode for the sign of imposed defocus. It is not clear whether the downstream neurons, the retinal ganglion cells, still have access to this information-and whether it ultimately reaches the brain. We have analyzed the spike rates of chicken retinal ganglion cells in vitro using a microelectrode array. For this purpose, we initially defined spatial resolution and contrast sensitivity in vitro. Two classes of chicken retinal ganglions were found, depending on the linearity of their responses with increasing contrast. Responses generally declined with increasing defocus of the visual stimulus. These responses were well predicted by the modulation transfer function for a diffraction-limited defocused optical system, the first Bessel function. Thus, the studied retinal ganglion cells did not distinguish between a loss of contrast at a given spatial frequency due to reduced contrast of the stimulus pattern or because the pattern was presented out of focus. Furthermore, there was no indication that the retinal ganglion cells responded differently to defocus of either sign, at least for the cells that were recorded in this study.

Investigation of PACAP Fragments and Related Peptides in Chronic Retinal Hypoperfusion

“…Some other members of this family have been localized in the vertebrate retina and several functions have been attributed to them [35, 36]. Glucagonergic amacrine cells represent a small subpopulation of the amacrine cells possibly playing a role in the visual processing [37, 38]. Other studies have shown that glucagon plays a role in eye bulb growth and glucagon is suggested to be an endogenous mediator of emmetropization [39].…”

Retinal cell imaging in myopic chickens using adaptive optics multiphoton microscopy

“…Earlier studies reported VR values ranging from 1.5 c/deg for 1-to 25-day-old chicks [43] to about 7 c/deg for 6-month old birds [44]. Later Demello and collaborators [45] [47]. In this work averaged values of 6.7 and 5.6 c/deg were obtained at the area centralis for emmetropic and myopic eyes respectively.…”

Analysis of the chicken retina with an adaptive optics multiphoton microscope

“…This variability is also present when computing the behavioral spatial resolution in chicks, ranging between 1.5 c/deg reported by Over and Moore [54] and 6.0-8.6 c/deg measured by Schmid and Wildsoet [55], and Diedrich and Schaeffel [53]. Our estimates are similar to Ghim and Hodos’ data [52] and higher than those reported by Diedrich and Schaeffel [53]. No data on MARP for different retinal eccentricities have been found in the literature to establish a comparison.…”

“…Values ranged between 140 c/deg for the eagle [24], 18 c/deg in pigeon [51], 6 c/deg for the quail [52] and about 4 c/deg in chicken [53]. This variability is also present when computing the behavioral spatial resolution in chicks, ranging between 1.5 c/deg reported by Over and Moore [54] and 6.0-8.6 c/deg measured by Schmid and Wildsoet [55], and Diedrich and Schaeffel [53]. Our estimates are similar to Ghim and Hodos’ data [52] and higher than those reported by Diedrich and Schaeffel [53].…”