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Xingfeng Li, Serge Dumoulin, Behzad Mansouri, Robert Hess; The fidelity of the retinotopic cortical map in amblyopia measured with BOLD-fMRI. Journal of Vision 2006;6(6):542. doi: 10.1167/6.6.542.
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© ARVO (1962-2015); The Authors (2016-present)
Purposes: To study the locations of early visual areas in amblyopia and the fidelity of their retinotopic maps using fMRI.
Methods: fMR images were acquired with a Siemens Sonata 1.5T. The stimuli consisted of abruptly randomly changing (8Hz) sharp-edged checkerboard stimuli of 80% contrast presented to either the normal or amblyopic eye of 11 amblyopic subjects and 6 normal controls. A phase-encoded design was used in which the attention of the subjects was controlled using a target detection task. All the known retinotopic visual areas were delineated by the normal and fellow amblyopic eye in V1 to V4. Correlation between the fixing eye boundaries and amblyopic eye boundaries as well as the boundaries between dominant and nondominant eyes in normal controls were compared. Distortion and variability in amblyopic eyes measured using a novel psychophysical mapping task were correlated to the phase variance in different cortical regions of our subject group.
Results: Boundaries in amblyopic subjects defined in term of fMRI retinotopic mapping using fixing eye and amblyopic eye show differences compared with normal controls. This could not be explained simply by the reduced signal-to-noise ratio of the amblyopic cortex. We did not find a strong correlation between the larger phase variances typical of amblyopic visual areas and distortion or variability measured psychophysically.
Conclusion: The fidelity of the retinotopic map is not as good in amblyopic eyes.
Supported by CIHR grant MOP53346 to RFH.
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