Quantitative aspects of the shift-effect in cat retinal ganglion cells

A sudden displacement of a pattern, even when far away from the classical border of a concentrically organized receptive field, elicits a transient excitatory response in on- and off-center retinal ganglion cells (shift-effect). Peak response and latency of the shift-effect have been studied under various stimulus conditions in on- and off-center ganglion cells. Increasing the retinal distance between the site of stimulation and receptive field yields responses of increasing latency corresponding to an intraretinal conduction velocity of about 0.35 m/sec. Beyond a distance of 20 degrees response amplitudes decrease steadily in on- and off-center neurons. Shift amplitude and contrast of the shifting grating have almost no influence above a threshold of 30 min of arc and 10-20% modulation respectively (all-or-none behavior). Shifts of decreasing velocity (600-10 degrees/sec) increase the latency. The response magnitude decreases only at very slow movements. Other properties of the shift-effect are briefly reported. Possible functional significances in relation to eye movements and brightness perception and the retinal pathway of the shift-effect are discussed.