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C. Chiao, R.H. Masland; Contextual Effects on Direction Selective Ganglion Cells in the Rabbit . Invest. Ophthalmol. Vis. Sci. 2003;44(13):3255.
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Purpose: Many experiments have studied the behavior of the ON-OFF direction selective (DS) ganglion cell but most of them have focused on the possible mechanism of the directional discrimination. This study was designed instead to evaluate the overall behavior of the cells in response to complex stimuli, with the goal of understanding their role in a rabbit's natural vision. Methods: Extracellular recordings of the DS ganglion cells were made from isolated rabbit retina preparation. In most of the experiments we used a standard, square wave stimulus to the receptive field center and varied the stimuli falling in the surround region. Results: (1) Spatial frequency tuning of the DS cells was quite different if the stimulus covered only the receptive field center or extended into the surround. If the grating included the surround the overall response was reduced significantly. This appeared to be due to inhibition generated by the bars as they crossed the boundary of the receptive field center. (2) If the center stimulus was 180 degrees out of phase with the surround, this inhibition was substantially reduced. (3) The same effect was observed for a stimulus consisting of a single long bar, i.e., phase shifting that portion of the bar that crosses the receptive field center increases the cell's response. (4) If the spatial frequency or temporal frequency of the surround stimulus were different from that of the center stimulus, the strength of the response to the center stimulus was preserved. Conclusions: These results may be summarized as suggesting that the ON-OFF DS cells are affected by disjunctions between movements occurring in the receptive field center and surround; more generally, by the characteristics of the center stimulus relative to events occurring in the surround.
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