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C Mora-Ferrer; Motion Detection In Goldfish: Retinal Gaba Versus Dopamine . Invest. Ophthalmol. Vis. Sci. 2002;43(13):4760.
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Purpose: Intra-vitreal injection of the D2-receptor antagonist sulpiride (10 mikroM) induces a loss of spectral sensitivity for motion detection, measured with the optomotor response, in goldfish (Mora-Ferrer & Gangluff, 2000). However, whether a D2-like mechanism reducing absolute sensitivity also affects the detection of a moving pattern at different angular speeds is unclear. The effect of sulpiride on motion detection at difference angular speeds was compared with the effect of bicuculline. This GABAa-receptor antagonists eliminates directional selectivity of retinal ganglion cells (Kittila & Massey, 1997). Methods: Goldfish were tested under bright white light by rotating a striped pattern cylinder around a circular tank. Animals followed the striped pattern by swimming along the pattern inside of the tank. The average swimming speed [in rounds per minute for angular speeds of 18, 30, 60 or 78 degree/second] was determined several times prior intravitreal injection of either sulpiride (10 mikroM) or bicuculline (10, 30 or 94.5 mikroM). Results: For both drug-injection protocols vehicle injection had no effect on the optomotor response of animals tested. Sulpiride also had no effect on the optomotor response behavior. Bicuculline however reduced the optomotor response in a dose dependent manner until a total loss of the optomotor response was observed. Conclusion: The loss in optomotor response due to bicuculline concentrations larger than 10 mikroM indicates a retinal motion detector which operates with GABAa-receptors. However, dopamine does not seem to have any effect on motion detection besides shifting the absolute threshold to higher intensities. View OriginalDownload SlideView OriginalDownload Slide
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