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Tom Van Grootel, Lynne Kiorpes; Neuronal response properties in area MT of an awake amblyopic macaque monkey. Journal of Vision 2015;15(12):651. doi: 10.1167/15.12.651.
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© ARVO (1962-2015); The Authors (2016-present)
Amblyopia is a visual deficit associated with abnormal visual experience in early life. Spatial and temporal vision is impaired in amblyopic observers viewing through their amblyopic eyes, and they also have deficits on motion tasks. Cortical area MT plays an important role in perception of motion, and previous work in anesthetized monkeys showed little disruption of single neuron response properties in amblyopic macaques. We recorded from single neurons in MT of an awake, fixating macaque with strabismic amblyopia, and compared responsiveness, direction selectivity, and spatial and temporal tuning properties when viewing through each eye. Neurons driven by the amblyopic eye were under-represented in the recorded population. In normal monkeys, almost all MT neurons are driven binocularly. Of our sample of 162 neurons, 94 could be influenced by amblyopic eye stimulation. Of the 94, 42 were untuned to visual stimulation of the amblyopic eye. The remaining 52 showed well-tuned responses to amblyopic eye stimulation and had similar tuning properties when driven by the fellow eye. However, firing rates were substantially reduced, and in some cases latency was longer, with the amblyopic eye viewing. These results confirm and extend previous work on amblyopic MT obtained under anesthesia. In the awake state, a clear reduction in responsiveness was found when the amblyopic eye was viewing. The reduced firing rate might reflect an upstream impediment feeding forward to MT or a disordered local summation mechanism. The amblyopic eye deficits in motion perception may be explained by the reduced magnitude and selectivity of MT responses evoked by stimulation of the amblyopic eye.
Meeting abstract presented at VSS 2015
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