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Venkata R. Posina, Gregory D. Horwitz, Thomas D. Albright; Distinct temporal dynamics of cone-opponent and -nonopponent macaque primary visual cortical neurons. Journal of Vision 2006;6(6):121. doi: 10.1167/6.6.121.
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© ARVO (1962-2015); The Authors (2016-present)
Receptive field maps of neurons in the primary visual cortex (V1) of awake, fixating monkeys were obtained by spike-triggered averaging (STA) of checkerboard stimuli modulated along the three cone-isolating directions. Receptive field centers were within the central 5 deg. Most of the cells (81%) that we studied were cone-opponent, and 79% of these cone-opponent neurons had an L-cone signal opposed to M- and S-cone signals (“L vs. M&S” neurons). Examination of the temporal profile of STAs showed that the times-to-peak of cone-nonopponent neurons were shorter than those of cone-opponent neurons (61 vs. 73 ms). The three subtypes of cone-opponent neurons (i.e. “L vs. M&S”, “M vs. L&S”, and “S vs. L&M”) had same times-to-peak. The times-to-peak of the three cone signals were same in most neurons. Most of the cone-nonopponent neurons (83%) were temporally biphasic, while only 22% of the cone-opponent neurons were biphasic. The times-to-peak of biphasic neurons were shorter than those of monophasic neurons. Even within the subset of biphasic neurons, the times-to-peak of cone-nonopponent neurons were shorter than those of cone-opponent neurons (54 vs. 66 ms). The temporal properties of cone-nonopponent and cone-opponent neurons are consistent with a difference in the proportion of magnocellular and parvocellular input to these two groups of V1 cells. Moreover, the observed temporal differences between cone-nonopponent and cone-opponent neurons parallel the differences between the psychophysical luminance and chromatic mechanisms.
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