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Christopher Shooner, Najib J. Majaj, Romesh D. Kumbhani, Luke E. Hallum, Corey M. Ziemba, J. Anthony Movshon, Lynne Kiorpes; Neural correlates of amblyopia in foveal and parafoveal visual cortex of amblyopic macaque monkeys. Journal of Vision 2014;14(10):689. doi: 10.1167/14.10.689.
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Amblyopia is a developmental disorder in which spatial vision is impaired in one eye. The physiological basis for amblyopia is unknown, but previous work has shown that the amblyopic eye often influences fewer cortical neurons than the non-amblyopic eye, and that these neurons prefer lower spatial frequencies on average. Earlier studies relied on single electrode recordings made in the representation of the parafovea in V1. We have now used 96-electrode arrays to record neuronal populations representing foveal and parafoveal visual space in areas V1 and V2 of 5 anesthetized and paralyzed macaques, 4 amblyopes and 1 control. Two amblyopes were anisometropic and two were strabismic. We recorded single neurons and multiunit clusters representing eccentricities between 0.5˚ and 5˚. A binocular mirror system allowed independent visual stimulation of each eye. We presented filtered spatiotemporal noise, each sample of which contained power in one of 6 spatial frequency bands with center frequencies ranging from 0.5 to 16 c/deg. We quantified eye dominance and spatial frequency preference for each recording site. All amblyopes tested showed eye dominance bias greater than that seen in the control animal. This bias was significantly greater in the fovea than in the near periphery in 3 of 4 amblyopes; one deep amblyope showed a strong bias at all eccentricities. In both anisometropic amblyopes, neurons driven by the dominant eye preferred higher spatial frequencies than those driven by the non-dominant eye, independently of eccentricity. This effect was evident in the foveal representation of one strabismic animal and altogether absent in the other animal. These observations confirm that experimental amblyopia affects both eye dominance and spatial frequency preference in early visual cortex. These effects depend both on the type of amblyopia (strabismic vs anisometropic) and on location in the visual field.
Meeting abstract presented at VSS 2014
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