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Max Snodderly; Awakening the visual cortex. Journal of Vision 2003;3(12):15. doi: 10.1167/3.12.15.
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© ARVO (1962-2015); The Authors (2016-present)
Since the 1950's the visual cortex has been explored with microelectrodes to define the properties of cortical neurons and to learn how they might contribute to visual perception. Initially recordings were made from anesthetized animals, where it was possible to present controlled stimuli while studying different types of neurons. The results, including those of Russ DeValois and his collaborators, have powerfully influenced thinking about perceptual processes, but they have always left the lingering doubt that something was missing. How can we understand perception by studying the brain of an animal that can not see? Our work has extended these studies to alert, behaving monkeys by careful controlling the stimulus and accounting for the effects of eye movements. We initially planned to focus on color vision mechanisms, but like Russ, found that there were many spatiotemporal factors that seemingly dominated the physiology. My colleagues and I have replicated many experiments performed in Russ's lab, usually (not always) with compatible results. However, I will review data showing that for alert monkeys the visual cortex emerges as even more precise, intricate, and differentiated once the confounding effects of anesthesia are removed. References: Snodderly DM, Gur M. Organization of striate cortex (V1) of alert, trained monkeys (Macaca fascicularis): Ongoing activity, stimulus selectivity, and widths of receptive field activating regions. J Neurophysiol. 1995; 74:2100–2125. Gur M, Beylin A, Snodderly DM. Response variability of neurons in primary visual cortex (V1) of alert monkeys. J Neurosci. 1997; 17: 2914–2920. Snodderly DM, Kagan I, Gur M. Selective activation of visual cortex neurons by fixational eye movements: Implications for neural coding. Vis Neurosci. 2001; 18: 259–277. Kagan I, Gur M, Snodderly DM. Spatial organization of receptive fields of V1 neurons of alert monkeys: comparison with responses to gratings. J Neurophysiol. 2002, 88:2557–2574.
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