The topographic distribution of the magnetic P100M to full- and half-field stimulation

Harding, Graham, Janday, Balwinder and Armstrong, Richard A. (1992). The topographic distribution of the magnetic P100M to full- and half-field stimulation. Documenta Ophthalmologica, 80 (1), pp. 63-73.

Abstract

Visual evoked magnetic responses were recorded to full-field and left and right half-field stimulation with three check sizes (70′, 34′ and 22′) in five normal subjects. Recordings were made sequentially on a 20-position grid (4 × 5) based on the inion, by means of a single-channel direct current-Superconducting Quantum Interference Device second-order gradiometer. The topographic maps were consistent on the same subjects recorded 2 months apart. The half-field responses produced the strongest signals in the contralateral hemisphere and were consistent with the cruciform model of the calcarine fissure. Right half fields produced upper-left-quadrant outgoing fields and lower-left-quadrant ingoing fields, while the left half field produced the opposite response. The topographic maps also varied with check size, with the larger checks producing positive or negative maximum position more anteriorly than small checks. In addition, with large checks the full-field responses could be explained as the summation of the two half fields, whereas full-field responses to smaller checks were more unpredictable and may be due to sources located at the occipital pole or lateral surface. In addition, dipole sources were located as appropriate with the use of inverse problem solutions. Topographic data will be vital to the clinical use of the visual evoked field but, in addition, provides complementary information to visual evoked potentials, allowing detailed studies of the visual cortex. © 1992 Kluwer Academic Publishers.

Publication DOI: https://doi.org/10.1007/BF00161232
Divisions: Life & Health Sciences > Optometry
Life & Health Sciences > Ophthalmic Research Group
Life & Health Sciences
Uncontrolled Keywords: calcarine fissure,magnetic responses,occipital pole,superconducting quantum interference device,topographic maps,visual fields,Ophthalmology
Full Text Link: http://www.springerlink.de/content/vq9335t856742102/?p=f3b07d9c21b64140b7b979e4612779ed&pi=0
Related URLs: http://www.scopus.com/inward/record.url?scp=0026479389&partnerID=8YFLogxK (Scopus URL)
Published Date: 1992-03
Authors: Harding, Graham
Janday, Balwinder
Armstrong, Richard A. ( 0000-0002-5046-3199)

Export / Share Citation


Statistics

Additional statistics for this record