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J J Wietsma

Publications and source records attributed to J J Wietsma.

5 recordsLinked to original sources
PubMed1995

Horizontal cells function normally in ethambutol-treated goldfish.

Ethambutol, a tuberculostatic drug, induces red-green colour vision defects in man and goldfish. The ethambutol-induced red-green colour vision defect in goldfish was argued to originate in the retina because after ethambutol application: (1) inhibitive interactions in red-green (double) opponent ganglion cells are lost [Van Dijk & Spekreijse, 1982 (Investigative Ophthalmology and Visual Science, 24, 128-133); Wietsma & Spekreijse, 1992 (Investigative Ophthalmology and Visual Science Suppl., 33, 1032)] and (2) the depolarizing responses to red light in the biphasic horizontal cells are reduced. To account for these findings Spekreijse, Wietsma and Neumeyer [(1991) Vision Research, 31, 551-562] suggested that ethambutol induced dark adaptation in the retina. In this paper the dark adaptation hypothesis is tested with the following results: (1) ethambutol changes only transiently the receptive field size and spectral sensitivity of horizontal cells; (2) the spectral characteristics of horizontal cells do not change in long-term ethambutol-treated goldfish; (3) formation of spinules on horizontal cell dendrites in cone terminals, a parameter for light adaptation, remains unaffected. Therefore we conclude that ethambutol does not induce functional dark adaptation of horizontal cells and that the ethambutol-induced red-green colour vision deficiency does not originate in the horizontal cell layers.

Action Potentials↗
PubMed1991

Separate processing of "color" and "brightness" in goldfish.

Spectral sensitivity was measured under different adaptation levels using a behavioral training technique in which the fish had to discriminate between a dark test field and a test field illuminated with monochromatic light. Depending on which of the two test fields was used as training test field, two functions were obtained which differ (1) in absolute sensitivity and (2) in shape. When trained on the dark test field, the fish seems to discriminate on the basis of a "color" cue, but it uses a "brightness" cue when trained on the illuminated test field. This was concluded from measurements of wavelength discrimination. Under low levels of the adaptation light (1.5 and 0.2 lx instead of 20 lx), the L-cone type contributes to perception of "brightness" but not to color vision. This difference in the adaptation behavior in the long-wavelength range was used to identify the ganglion cells which may represent channels for "brightness" and "color" in the retina. Action spectra were recorded extracellularly at different levels of dark- and light-adaptation.

Animals↗
PubMed1991

Induced color blindness in goldfish: a behavioral and electrophysiological study.

To answer the question whether, like man, ethambutol treated fish would become color-blind, wavelength discrimination was measured behaviorally in goldfish, preceding, during and after ethambutol treatment. The results are that of the three high discrimination abilities at around 400, 500 and 600 nm, ethambutol affected the latter one. Red-green discrimination is lost reversibly leaving the discriminations in the blue-green and violet range unaffected. This red-green discrimination deficiency cannot be accounted for by a loss of long wavelength cones since the ERG and luminosity functions remain unaffected. Intracellular horizontal cell recordings in goldfish show that ethambutol hyperpolarizes all three types of cone driven horizontal cells and changes their color coding such that their spectral characteristics become cone-like as is the case in dark adapted retina. So, the initial effect induced by ethambutol seems to be an adaptation deficiency in color vision related tasks. Human wavelength discrimination and increment threshold spectral sensitivity functions obtained at low luminance levels are compared to behavioral functions in ethambutol treated goldfish. The high similarity between the ethambutol effects in man and goldfish, and the effects observed in the horizontal cell responses in goldfish are highly indicative that horizontal cells play a key role in color vision. So far their function has been puzzling.

Animals↗
PubMed1991

Bicuculline produces reversible red-green color blindness in goldfish, as revealed by monocular behavioral testing.

The effect of the GABAA receptor antagonist bicuculline (methiodide) on goldfish wavelength discrimination was studied. This was done using a behavioral two alternative forced choice procedure at training wavelengths 500 and 600 nm, where goldfish wavelength discrimination is the best. During the experiments the goldfish could use only the eye that was intravitreally injected with bicuculline; the other eye was covered. In control experiments, to exclude systemic effects, the covering of the eyes was reversed. Bicuculline induced loss of wavelength discrimination ability around 600 nm, while this ability was not affected around 500 nm. The effect was reversible, since discrimination around 600 nm returned to normal within a day after injection. The results indicate that GABAA receptor mediated processes, like horizontal cell to cone feedback, play an important role in wavelength discrimination at the long wavelength part of the spectrum.

Animals↗