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FRANKLIN G. HEMPEL; Rabbit Visual Potentials After Laser Photocoagulation. Invest. Ophthalmol. Vis. Sci. 1971;10(9):639-649.
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Light and electrically evoked responses of the rabbit lateral geniculate nucleus and visual cortex were monitored before and after ruby laser photocoagulation of a 0.6 cm. wide retinal field. The electroretinogram was also recorded. Severe lesions, especially those inflicted by laser energy densities of 6.3 joules (J) per square centimeter, result in a substantial reduction or even elimination of geniculate and cortical potentials evoked by photic stimuli while the electroretinogram b-wave is reduced maximally about 30 per cent. Less severe lesions produced by energy densities near 2 to 3 J per square centimeter cause a mean increase in geniculate and cortical response to low-intensity photic stimulation but not to high-intensity stimulation at a time that the electroretinogram is reduced in amplitude. The postsynaptic component of the response of the lateral geniculate nucleus and the visual cortex potential, both elicited by electrical shock of the optic nerve, are enhanced after irradiation with an energy density of 3.2 J per square centimeter or more. The data suggest that the laser insult acts to uncouple the tonic inhibition imposed on the higher visual centers by the retina, i.e., the lesion produces a disinhibition similar to that obtained when afferent visual impulses are interrupted by ocular ischemia or enucleation.
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