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Article: Estimating retinal fixation location using fMRI

TitleEstimating retinal fixation location using fMRI
Authors
Issue Date2003
PublisherAssociation for Research in Vision and Ophthalmology. The Journal's web site is located at http://wwwjournalofvisionorg/
Citation
Journal Of Vision, 2003, v. 3 n. 9, p. 363a How to Cite?
AbstractPurpose. We are developing a method for retinotopic mapping of the visual cortex in people with central field loss. Retinotopic mapping based on polar coordinates uses rotating wedges and expanding rings, which assume stable foveal fixation. However, people with central field loss usually adopt a non-foveal retinal location for fixation and that location is typically unknown. Therefore, instead of using the polar-coordinate based mapping method, which requires a known origin, we developed a set of phase-coded mapping stimuli in Cartesian coordinates that will also allow us to estimate the fixation locations relative to the unknown fovea location. The current study aims to validate this new mapping procedure in observers with normal vision. Method. High-resolution structural and functional MR images were acquired on a Siemens 3T system. Two mapping stimuli were used. Both were 2 deg wide checkered bars, which extended across the full-display. One was a vertical bar moving across the screen from left to right. The other was a horizontal bar that moved from top to bottom. In both cases, the bar traversed the display 4 times, each pass taking 72 s. Since the subjects fixated on a dot at the center of the display, the bars should cross the fixation at the mid-point of the 72-second period. This time point was compared with the time point when the bars cross the fovea, which was estimated by deriving the switch of V1 activation from one hemisphere to the other hemisphere produced by the vertical bar, and from the lower bank to the upper bank of the calcarine sulcus produced by the horizontal bar. Results. With this new method, the estimated fovea locations were within 2 deg from the actual locations. Conclusions. Our new stimuli allow us to estimate the fixation location with acceptable precision. This new procedure may be useful for retinotopic mapping on people with central field loss.
Persistent Identifierhttp://hdl.handle.net/10722/169042
ISSN
2015 Impact Factor: 2.341
2015 SCImago Journal Rankings: 1.042

 

DC FieldValueLanguage
dc.contributor.authorCheung, SHen_US
dc.contributor.authorHe, Sen_US
dc.contributor.authorCarlson, TAen_US
dc.contributor.authorLegge, GEen_US
dc.contributor.authorHu, Xen_US
dc.date.accessioned2012-10-08T03:41:04Z-
dc.date.available2012-10-08T03:41:04Z-
dc.date.issued2003en_US
dc.identifier.citationJournal Of Vision, 2003, v. 3 n. 9, p. 363aen_US
dc.identifier.issn1534-7362en_US
dc.identifier.urihttp://hdl.handle.net/10722/169042-
dc.description.abstractPurpose. We are developing a method for retinotopic mapping of the visual cortex in people with central field loss. Retinotopic mapping based on polar coordinates uses rotating wedges and expanding rings, which assume stable foveal fixation. However, people with central field loss usually adopt a non-foveal retinal location for fixation and that location is typically unknown. Therefore, instead of using the polar-coordinate based mapping method, which requires a known origin, we developed a set of phase-coded mapping stimuli in Cartesian coordinates that will also allow us to estimate the fixation locations relative to the unknown fovea location. The current study aims to validate this new mapping procedure in observers with normal vision. Method. High-resolution structural and functional MR images were acquired on a Siemens 3T system. Two mapping stimuli were used. Both were 2 deg wide checkered bars, which extended across the full-display. One was a vertical bar moving across the screen from left to right. The other was a horizontal bar that moved from top to bottom. In both cases, the bar traversed the display 4 times, each pass taking 72 s. Since the subjects fixated on a dot at the center of the display, the bars should cross the fixation at the mid-point of the 72-second period. This time point was compared with the time point when the bars cross the fovea, which was estimated by deriving the switch of V1 activation from one hemisphere to the other hemisphere produced by the vertical bar, and from the lower bank to the upper bank of the calcarine sulcus produced by the horizontal bar. Results. With this new method, the estimated fovea locations were within 2 deg from the actual locations. Conclusions. Our new stimuli allow us to estimate the fixation location with acceptable precision. This new procedure may be useful for retinotopic mapping on people with central field loss.en_US
dc.languageengen_US
dc.publisherAssociation for Research in Vision and Ophthalmology. The Journal's web site is located at http://wwwjournalofvisionorg/en_US
dc.relation.ispartofJournal of Visionen_US
dc.titleEstimating retinal fixation location using fMRIen_US
dc.typeArticleen_US
dc.identifier.emailCheung, SH:singhang@hku.hken_US
dc.identifier.authorityCheung, SH=rp00590en_US
dc.description.naturelink_to_subscribed_fulltexten_US
dc.identifier.doi10.1167/3.9.363en_US
dc.identifier.scopuseid_2-s2.0-4243130646en_US
dc.identifier.volume3en_US
dc.identifier.issue9en_US
dc.identifier.spage363aen_US
dc.publisher.placeUnited Statesen_US
dc.identifier.scopusauthoridCheung, SH=7202473508en_US
dc.identifier.scopusauthoridHe, S=7402691306en_US
dc.identifier.scopusauthoridCarlson, TA=7101885607en_US
dc.identifier.scopusauthoridLegge, GE=7005064208en_US
dc.identifier.scopusauthoridHu, X=34770364200en_US

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