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This Article Full Text Full Text (PDF) All Versions of this Article: 583/1/159    most recent jphysiol.2007.136242v1 Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Conner, I. P. Articles by Mendola, J. D. Search for Related Content PubMed PubMed Citation Articles by Conner, I. P. Articles by Mendola, J. D. Related Collections Neuroscience

West Virginia University
¹ Department of Radiology and Center for Advanced Imaging
² Department of Neurobiology and Anatomy
³ Department of Ophthalmology, Morgantown, WV 26506-9236, USA

Amblyopia is a developmental visual disorder associated with loss of monocular acuity and sensitivity as well as profound alterations in binocular integration. Abnormal connections in visual cortex are known to underlie this loss, but the extent to which these abnormalities are regionally or retinotopically specific has not been fully determined. This functional magnetic resonance imaging (fMRI) study compared the retinotopic maps in visual cortex produced by each individual eye in 19 adults (7 esotropic strabismics, 6 anisometropes and 6 controls). In our standard viewing condition, the non-tested eye viewed a dichoptic homogeneous mid-level grey stimulus, thereby permitting some degree of binocular interaction. Regions-of-interest analysis was performed for extrafoveal V1, extrafoveal V2 and the foveal representation at the occipital pole. In general, the blood oxygenation level-dependent (BOLD) signal was reduced for the amblyopic eye. At the occipital pole, population receptive fields were shifted to represent more parafoveal locations for the amblyopic eye, compared with the fellow eye, in some subjects. Interestingly, occluding the fellow eye caused an expanded foveal representation for the amblyopic eye in one early–onset strabismic subject with binocular suppression, indicating real-time cortical remapping. In addition, a few subjects actually showed increased activity in parietal and temporal cortex when viewing with the amblyopic eye. We conclude that, even in a heterogeneous population, abnormal early visual experience commonly leads to regionally specific cortical adaptations.

(Received 11 May 2007; accepted after revision 15 June 2007; first published online 21 June 2007)
Corresponding author J. D. Mendola: Center for Advanced Imaging, West Virginia University Health Sciences Center, Morgantown, WV 26506-9236, USA. Email: jmendola{at}hsc.wvu.edu