Receptive field organization of ganglion cells in the frog retina: contributions from cones, green rods and red rods.

Abstract

SUMMARY1. The impulse discharge of ganglion cells was recorded with extracellular micro-electrodes in the excised and opened eye of the common frog, Rana temporaria.2. When a single unit was isolated, the cell type was first determined according to the Maturana, Lettvin, McCulloch & Pitts (1960) classification with the aid of varying moving and stationary stimuli.3. Class 4 cells respond only to a decrease of light when cones are stimulated but respond to an increase of light when green rods are stimulated. A distinct class of deviating class 4 cells was found that give a brief high frequency burst at 'off' from their small excitatory receptive fields (ERF); unlike typical class 4 cells they possess a purely inhibitory surrounding field (IRF).4. The contributions from the cones and the green and red rods were isolated by measuring the thresholds of the discharges with on-off stimuli of varying wave-lengths against strong yellow backgrounds, or against a very weak background or no background at all. The spatial distribution of the contributions to the ERF was determined by mapping threshold profiles, and additional information about ERF and IRF was obtained from area-threshold curves.5. The cone-mediated ERFs were found to be 0-06-0-50 mm wide (1.5-12 degrees of visual field), which agrees well with the sizes of the dendritic trees of the ganglion cells. The green rod-mediated ERFs can be 0-5-1.5 mm wide and have less distinct boundaries than the conemediated. The green rod-mediated ERF of an individual ganglion cell is always larger than the cone-mediated ERF of the same cell. The red rodmediated ERFs seem to be somewhat larger than the cone-mediated but smaller than the green rod-mediated. 6. The green rods contribute only to the on thresholds of class 1, 2

Adaptation of cone pigments found in green rods for scotopic vision through a single amino acid mutation

“…5). Electrophysiological evidence from frogs shows that green rods transduce signals to most retinal ganglion cells, some of which can also receive inputs from red rods (31)(32)(33)(34). Thus, the decrease of the thermal isomerization rates of anuran blue-sensitive cone pigments in green rods enables them to function in tandem with green-sensitive red (normal) rods for scotopic vision, which could provide a molecular basis for color discrimination under the dark conditions.…”

Glycinergic and GABAergic control of intensity-response function of frog ERG waves under different conditions of light stimulation

“…Predominantly cone mediated responses were obtained by using red test stimuli (k > 610 nm cutoff ®lter) presented on a blue-green background (interference ®lter 500 nm) with an intensity of 3.8´10 5 quanta s ±1 lm ±2 in order to saturate rods. Responses mediated mainly by green rods were obtained using blue test stimuli (interference ®lter 430 nm half bandwidth 10 nm) superimposed on a green background (interference ®lter 550 nm half bandwidth 10 nm) with an intensity of 7.1´10 5 quanta s ±1 lm ±2 , which is considered to saturate red rods and to suppress the cone sensitivity selectively (Backstrom & Reuter 1975). The ERG was recorded by means of non-polarized Ag/AgCl electrodes at a bandpass of 0.1±1000 Hz.…”

Identification of cone classes in Xenopus retina by immunocytochemistry and staining with lectins and vital dyes

“…For a period of time, the blue-sensitive rod was of interest in relation to a possible role in color coding. That is, the amphibian retina contains color-coded horizontal and ganglion cells, one component of which is blue-sensitive (Backstrom & Reuter, 1975;Ogden et al, 1985;Yang et al, 1983;Stone et al, 1990). The responses of the blue-sensitive rod, however, whether expressed in the PHI component of the ERG (Witkovsky et al, 1981) or measured directly as photocurrents (Matthews, 1983), are slow, resembling closely those of the principal 523 rod.…”