THE VISUALLY EVOKED SUB-CORTICAL POTENTIAL - IS IT RELATED TO THE ELECTRORETINOGRAM

  • 1 January 1981
    • journal article
    • research article
    • Vol. 21  (2) , 335-344
Abstract
The visually evoked subcortical potential (VESP) of mean latencies P21-N28-P36 was previously recorded at an electrode site around the mastoid process. An initial topographical study of the potential indicated that it was independent of the electroretinogram (ERG), and monocular stimulation showed bilateral reduction, which suggests that the VESP is of postchiasmal origin. A more detailed topographical study of the scalp and facial distribution of the ERG and its oscillatory potentials was carried out, with simultaneous recording of the VESP. Two monocular fields of ERG activity were demonstrated, each having a wide area of distribution and interacting medially. Remnants of the ERG b-wave were detected at many electrode sites, but they were of different amplitude and morphology from the VESP. Results are presented from 2 atypical control subjects and 2 patients, providing further evidence of the separate genesis of the ERG and VESP.

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