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Experimental Brain Research

, Volume 36, Issue 1, pp 53–69 | Cite as

Hemisphere contributions to the composition of the pattern-evoked potential waveform

  • L. D. Blumenhardt
  • A. M. Halliday
Article

Summary

The transverse distribution of scalp-recorded potentials evoked by pattern reversal stimulation was studied in 50 healthy subjects.

In most individuals the full-field responses were symmetrical over the occipital scalp, but important variations in distribution, symmetry and waveform were recorded in some cases. Asymmetrical responses were similar for each eye (i.e., they were “uncrossed” or homonymous asymmetries). Full-field peak latencies and amplitudes in the lateral channels were more variable than those at midline electrodes.

Half-field responses were markedly asymmetric with well-lateralised components widespread over occipital-parietal scalp. In contrast to the full-field responses, component values measured near the midline were less consistent than those from lateral channels due to waveform distortions in this area (“transitional zone”). Upper field stimulation is particularly likely to produce such midline waveform distortions. Activity recorded from the scalp contralateral to the half-field stimulated shows more inter-individual and inter-hemispheric variation than that recorded from ipsilateral electrodes.

Variants in the full-field waveform can be accounted for by relative differences in amplitude and distribution of the ipsilateral and contralateral components from each half field. The algebraic sum of these half-field components does not differ significantly from the components of the separately recorded full-field response. Furthermore, responses from the surviving half-field in patients after total hemispherectomy contain all the ipsilateral and contralateral half-field components seen in healthy subjects.

Key words

Pattern evoked potentials Waveform variation Half-field responses 

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References

  1. Barrett, G., Blumhardt, L.D., Halliday, A.M., Halliday, E., Kriss, A.: Paradoxical reversal of lateralisation of the half-field pattern-evoked response with monopolar and bipolar electrode montages. J. Physiol. (Lond.) 258, 63–64 (1976a)Google Scholar
  2. Barrett, G., Blumhardt, L.D., Halliday, A.M., Halliday, E., Kriss, A.: A paradox in the lateralisation of the visual evoked response. Nature 261, 253–255 (1976b)Google Scholar
  3. Beauchamp, M., Matthews, W. B., Small, D., Stein, J.F.: The topography of the visual evoked response to half-field stimulation. J. Physiol. (Lond.) 260, 46–47 (1976)Google Scholar
  4. Blumhardt, L.D., Barrett, G., Halliday, A.M.: The asymmetrical visual evoked potential to pattern reversal in one half-field and its significance for the analysis of visual field defects. Br. J. Ophthalmol. 61, 454–461 (1977a)Google Scholar
  5. Blumhardt, L.D., Barrett, G., Halliday, A.M., Kriss, A.: The contralateral negativity of the half-field response and its association with central scotomata. Electroencephalogr. Clin. Neurophysiol. 43, 286 (1977b)Google Scholar
  6. Blumhardt, L.D., Barrett, G., Halliday, A.M., Kriss, A.: The effect of experimental ‘scotomata’ on the ipsilateral and contralateral responses to pattern reversal in one half-field. Electroencephalogr. Clin. Neurophysiol. 45, 376–392 (1978)Google Scholar
  7. Jeffreys, D.A., Axford, J.G.: Source locations of pattern-specific components of human visual evoked potentials. I. Component of striate cortical origin. Exp. Brain Res. 16, 1–21 (1972)Google Scholar
  8. Regan, D., Heron, J. R.: Clinical investigation of lesions of the visual pathway: a new objective technique. J. Neurol. Neurosurg. Psychiatry 32, 479–483 (1969)Google Scholar
  9. Regan, D., Cartwright, R.F.: A method of measuring the potentials evoked by simultaneous stimulation of different retinal regions. Electroencephalogr. Clin. Neurophysiol. 28, 314–319 (1970)Google Scholar
  10. Rietveld, W.J., Tordoir, W.E., Hagenouw, J.R., Lubbers, J.A., Spoor, A.C.: Visual evoked responses to blank and checker-board patterned flashes. Acta Physiol. Pharmacol. Neerl. 14, 259–285 (1967)Google Scholar
  11. Wildberger, H.G.H., Van Lith, J.H.M., Wijngaarde, R., Mak, G.T.M.: Visually evoked cortical potentials in the evaluation of homonymous and bitemporal visual field defects. Br. J. Ophthalmol. 60, 273–278 (1976)Google Scholar

Copyright information

© Springer-Verlag 1979

Authors and Affiliations

  • L. D. Blumenhardt
    • 1
  • A. M. Halliday
    • 1
  1. 1.Medical Research Council, Institute of NeurologyNational Hospital for Nervous DiseasesLondonEngland

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