Topographic mapping of the pattern onset evoked magnetic response to stimulation of different portions of the visual field

Graham F A Harding*, Christopher Degg, Stephen J. Anderson, Ian Holliday, Fiona Fylan, Gareth Barnes, James Bedford

*Corresponding author for this work

Research output: Contribution to journalArticle

Abstract

Visual evoked magnetic responses to pattern onset/offset stimuli were recorded in 5 normal subjects. The outgoing and ingoing magnetic currents were seen maximally over the contralateral visual cortex to the half field stimulated in the majority of subjects. The distribution of magnetic currents with half field stimulation would be consistent with a dipole on the midline with the positive and pointing laterally. Quadrantic stimuli produced dipoles which would be consistent with a vector sum of dipoles situated, in the case of upper quarter field stimulation, in the lingual gyri on the floor of the calcarine fissure. Lower quadrantic stimulation produced a vector consistent with dipoles on the cuneal gyrus and on the ceiling of the calcarine fissure producing a resultant vector. The use of paired octant stimuli to improve localisation was demonstrated on both right left and upper and lower half fields.

Original languageEnglish
Pages (from-to)175-183
Number of pages9
JournalInternational Journal of Psychophysiology
Volume16
Issue number2-3
DOIs
Publication statusPublished - 1994

Keywords

  • Calcarine fissure
  • Multi channel magnetic recording
  • Neuromagnetometry
  • Pattern onset/offset
  • Visual evoked magnetic responses

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