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Krista R. Kelly, Keith A. Schneider, Brenda L. Gallie, Jennifer K.E. Steeves; Reduced LGN volume following early monocular deprivation from enucleation. Journal of Vision 2012;12(9):1359. doi: 10.1167/12.9.1359.
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Background. The lateral geniculate nucleus (LGN) is a bilateral thalamic nucleus receiving information from each eye in separate layers. How is geniculate development affected when one eye is surgically removed (enucleation), consequently eliminating half of its retinal inputs? Animal models of eye enucleation suggest decreased LGN volume ipsilateral to the remaining eye in rabbits (Khan, 2005). Prenatal enucleation in monkeys is associated with a failure of layers to segregate, however, synaptic connections are formed between the remaining eye and neurons that would have otherwise been allocated to the enucleated eye (Rakic, 1981). LGN gray matter is decreased in humans following early monocular pattern deprivation from strabismus (Barnes et al., 2010). It is not known, however, how geniculate development is affected by monocular enucleation in humans. Methods. LGN volume of adults enucleated early in life due to retinoblastoma (cancer of the retina) was compared to that of binocularly intact controls. A series of 40 high-resolution proton density-weighted images were acquired with a 3T MRI scanner. Each series of scans were then registered and averaged. Raters used these averaged scans to manually identify and trace LGN regions of interest in each participant. Results. Individuals with monocular enucleation had a significant overall decrease in LGN volume compared to controls. However, this decrease was significantly less prominent in the hemisphere contralateral to the remaining eye. Conclusions. Our data suggest LGN cell degeneration due to the deafferentation of one half of visual inputs early in life. Further, the less pronounced decrease in LGN volume contralateral to the remaining eye suggests that the earlier developing crossed fibres may recruit some of the deafferented cells previously allocated to the enucleated eye.
Meeting abstract presented at VSS 2012
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