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Bartlet D. Moore, IV, Henry J. Alitto, W. Martin Usrey; The influence of stimulus temporal frequency on orientation tuning and direction selectivity in V1 neurons. Journal of Vision 2004;4(8):274. doi: 10.1167/4.8.274.
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© ARVO (1962-2015); The Authors (2016-present)
The activity of neurons in primary visual cortex is influenced by the orientation, contrast, and temporal frequency of a visual stimulus. This raises the question of how these stimulus properties interact to shape cortical responses. While past studies have shown that the bandwidth of orientation tuning is invariant to stimulus contrast, we know little about the influence of temporal frequency on orientation tuning. In the present study, we examined the effect of temporal frequency on orientation-tuning as well as direction selectivity in ferret primary visual cortex. Using extracellular recording techniques, temporal-frequency response functions were measured for individual neurons using drifting sine-wave gratings of optimal spatial frequency. Orientation tuning curves were then made using each neuron's preferred temporal frequency as well as 4 other temporal frequencies: the two temporal frequencies that evoked a half-maximum response on the rising and falling phase of the temporal-frequency response function, and the two temporal frequencies that evoked a 20% maximum response. Our results show that the bandwidth of orientation tuning in ferret V1 is invariant to temporal frequency. In contrast, direction selectivity is influenced by temporal frequency as direction selectivity decreased with both high and low temporal frequencies. This disparity in the effects of temporal frequency suggests distinct mechanisms contribute to the orientation tuning and direction selectivity of cortical neurons. Supported by NIH EY13588, EY12576, the McKnight Foundation, the Esther A. and Joseph Klingenstein Fund, and the Alfred P. Sloan Foundation.
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