Abstract
Stimulus and analysis parameters have been adjusted to provide optimum conditions for producing and recording the early components of the flash VEPs. A visual evoked potential of mean latency P20-N26-P34 has been recorded in 93% of normal subjects maximally from an electrode position slightly posterior to the Rolandic/Sylvian fissure and around the upper mastoid process.
This potential is topographically separated from the lid ERG and the occipital VECP. Monocular stimulation shows abolition of the ERG ipsilateral to occlusion but bilateral reduction of the amplitude of the P20-N26-P34 potential, indicating that the wave is independent of the ERG and optic nerve and must be arising from a post-chiasmal site.
Patients with homonymous hemianopia of both cortical and subcortical origin, and bitemporal hemianopia have been studied and the results obtained are consistent with potentials arising from a post-chiasmal but infra-cortical site. In view of these results and those of the topographical studies indicating a non-retinal and non-optic nerve origin we have entitled these components’ visual evoked subcortical potentials’ (VESPs).
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Harding, G.F.A., Rubinstein, M.P. (1981). Early Components of the Visual Evoked Potential in Man. In: Spekreijse, H., Apkarian, P.A. (eds) Visual Pathways. Documenta Ophthalmologica Proceedings Series, vol 27. Springer, Dordrecht. https://doi.org/10.1007/978-94-009-8656-5_5
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DOI: https://doi.org/10.1007/978-94-009-8656-5_5
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