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Timothy Gawne, Allan Dobbins, Franklin Amthor; The Responses of On-Off Directionally Selective Retinal Ganglion Cells to Sudden Motion-Onset. Journal of Vision 2014;14(10):284. doi: https://doi.org/10.1167/14.10.284.
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© ARVO (1962-2015); The Authors (2016-present)
Introduction On-Off Directionally-Selective Retinal Ganglion cells (DS RGCs) are robustly tuned for the direction of a moving visual stimulus, but it is still not clear what their role in perception is. One possibility could be in responding to the motion onsets caused by head movements, which are important in computing distance via motion parallax. Because On-Off DS RGCs exhibit hyperacuity-level discrimination for small movements (Grzywacz et al. 1994), these cells might be especially well suited for this task. Methods Pigmented rabbit retinas were prepared for single-unit recording in a superfused eyecup preparation. A video image was projected onto the retina. Visual stimuli were flashed in the center of the RF, allowed to stabilize for one second, then moved abruptly at different speeds and directions. Results Response latency decreased with increasing speeds, with relatively little effect of stimulus direction or luminance. On the other hand, the response magnitude (spike count) was a strong function of stimulus direction, with relatively less effect of stimulus speed or luminance. Using only the first 300 msec of a single response, a neural network predicted the stimulus speed (actual vs. predicted R=0.85). Again using only the first 300 msec and a single trial, a simulated quartet of cells with complementary directional tuning predicted the stimulus direction (actual vs. predicted R=0.89). Conclusion Stimulus speed is encoded via the high frequency content of the spike train, while stimulus direction is encoded in the low-frequency information, permitting straightforward decoding. The experiments and simulations demonstrate that an object's speed and direction can be obtained rapidly after movement onset by On-Off DS RGCs.
Meeting abstract presented at VSS 2014
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