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Yaoguang Jiang, Dmitry Yampolsky, Gopathy Purushothaman, Vivien Casagrande; Neural Sensitivity in the Lateral Geniculate Nucleus (LGN) of Awake, Behaving Monkeys during a Contrast Detection Task: Comparison of Neurometric and Psychometric Functions. Journal of Vision 2013;13(9):1026. doi: 10.1167/13.9.1026.
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Electrophysiological recordings in the early visual pathway of mammals revealed great sensitivities in detecting contrast changes at the level of retinal ganglion cells (RGCs) (Enroth-Cugell & Robson 1966, Kaplan & Shapley 1986), the lateral geniculate nucleus (LGN) (Hubel & Wiesel 1961, Shapley et al. 1981, Derrington & Lennie 1984), and the primary visual cortex (V1) (Ohzawa et al. 1985, Sclar et al. 1990). In each of these areas it was concluded that the most sensitive neurons could potentially explain the contrast sensitivity of the subject (see Barlow et al. 1971 for RGC, Kang & Malpeli 2009 for LGN, Tolhurst et al. 1983 and Hawken & Parker 1990 for V1 sensitivity), but the sensitivities of these neurons have not been directly measured while the subject is actively performing a contrast detection task. Additionally it is unclear how (or if) the magno (M) and parvo (P) retinothalamic pathways contribute differently to a contrast detection task in awake animals. Applying receiver operating characteristic (ROC) analysis to single LGN neurons recorded from monkeys performing a two-alternative, forced choice (2-AFC) contrast detection task, we derived a neurometric function for each neuron and compared its sensitivity to that of the animal. We found that LGN P and M neurons were consistently less sensitive than the monkey, and the development of their neurometric functions over time reflected the temporal dynamics of the visually driven response of LGN P and M neurons, respectively. By computing choice probability (CP) we characterized the relationship between single neuron responses in the LGN and the behavioral choice of the animal (Britten et al. 1996). We found that both P and M neurons’ activities were weakly correlated with the monkey’s choice, and the development of their CPs over time cannot be fully explained by the temporal dynamics of their visually driven responses.
Meeting abstract presented at VSS 2013
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