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Doh-Yeon Kim, Han-Kyun Choi, Chang-Sub Jung; Gap Junction Contributions To The Goldfish Full-field Electroretinogram In The Photopic Illumination Level. Invest. Ophthalmol. Vis. Sci. 2012;53(14):2454.
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Understanding how the b-wave of the electroretinogram (ERG) is generated by a full-field light stimulation is still a challenge in visual neuroscience. Historically the b-wave amplitude involved the signals from ON-center bipolar cells, müller cells, and the third order cells. However to understand more of the origin of the b-wave, we studied the contribution of the gap junction on the ERG as well as on the visual motor response. Many types of retinal neurons are connected to their homologous neighbors by gap junctions.
The full-field flash photopic (cone-dominated) ERG was recorded from goldfish (Carassius auratus) using a corneal electrode. The visual motor response was verified measuring the optomotor response .The data were obtained before and after intraocular injection of the drugs into both eyes under the photopic illumination level.
Even most of the gap junction blockers - cabenoxolone, meclofenamic acid, 18-beta-glycyrrhetinic acid, and octanol - augmented the amplitude of the b-waves greatly from 35% to 120% without decreasing of d-waves but afford no alteration to the OMRs. The a-, c- and d-waves were not particularly changed by gap-junction blockers. It has been generally known that the OMRs reduced dramatically when b-wave was eliminated by exposing the retina to drugs which could block the activity of ON-center bipolar cells. On the contrary, the enhancement of b-wave by gap junction blocker does not increase the visual motor responses. Blocking of the gap-junction in the whole retina greatly induces the augmentation of the b-wave on a light-adapted eye.
The results indicate that gap junction activity influences b-wave of the ERG. These considerable augmentations of the b-wave do not lead to the incensement of the visual motor responses under the photopic condition.
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