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Robert Hess, Kathy T. Mullen, Benjamin Thompson, Glen Gole; LGN abnormalities in human amblyopes revealed by high-field fMRI. Journal of Vision 2008;8(6):957. doi: 10.1167/8.6.957.
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© ARVO (1962-2015); The Authors (2016-present)
Aims. To compare the responsiveness of the LGN (lateral geniculate nucleus) when driven by the fixing and fellow amblyopic eye in a group of adult amblyopes. Methods. MR images were acquired on a 4T Bruker MedSpec scanner using a TR of 1.5sec. A binocular localizer was used to establish an ROI for the left and right LGN for each of 5 amblyopic observers. Stimuli were flickering (8Hz) coloured checkerboards that were presented in a block design alternating between the stimulus and a blank of zero luminance. LGN activation driven by fixing and fellow amblyopic eyes was compared. Results. Clear interocular response differences were observed in all five amblyopic subjects with stronger responses (peak and integrated response activity) coming from the fixing eye. Across our sample of amblyopes there was a significantly weaker response from the amblyopic eye for 9 out of the 10 LGNs. Conclusions. There is an amblyopic eye processing deficit at the level of the LGN. A previous VBM study (Barnes et al, HBM 2006 abst.) suggested a significant correlation between the functional deficit in the cortex and LGN structure in human amblyopes. Here we show that LGN function, when driven by the amblyopic eye, is anomalous.
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