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NS Garina, VG Erchenkov; Changes Of The Visual Center Focal Light Evoked Potentials In Response To The Light Spote Stimulus Under The Retinal Bicuculline Application In Fish . Invest. Ophthalmol. Vis. Sci. 2002;43(13):4734.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To investigate the influences of the retinal bicuculline application on the focal light-spot evoked responses in the primary visual center with the topical retinal projection. Methods: The focal evoked potentials in response to white light spot (200 mcm diameter spot on the retinal surface) were simultaneously registered inside and outside the projection zone for the retinal illuminated area in the fish primary visual center (tectum opticum) of the cod (Gadus morrhua). Bicuculline (10-4 M; 20 mkl) was injected into the opened eye under the short-lasting illumination by the red dim light. The first postsynaptic components of the evoked potentials in response to the light on-set were analyzed. Results: The bicuculline applications did not significantly change or slight decreased the amplitude of the focal evoked potentials in the tectal projection zone for illuminated retinal locus. The great increase (up to 150-200%) of the low amplitude responses or the response appearance were observed outside this tectal zone. Thus, the tectal focal evoked potentials became the same in the both registered areas. Conclusion: The results show, that retinal bicuculline application increases or provokes the appearance of the tectal response to the local light stimulus outside the tectal projection zone of the illuminated retinal area. So, the topical retino-tectal projection might be destroyed throught the retinal cells GABAa-receptors. We hypothesize, that bicuculline-induced blockade of the retinal GABAa- receptors declines lateral retinal inhibition and leads to the intraretinal signal spreading.
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