Receptive field organization of ‘sustained’ and ‘transient’ retinal ganglion cells which subserve different functional roles

Abstract

1. Post‐stimulus histograms were obtained from ‘sustained’ and ‘transient’ retinal ganglion cells for receptive field plots using a light spot with square‐wave modulation of intensity, and of variable intensity and area. Fundamental differences in their receptive field organization in time and space were revealed. 2. In ‘sustained’ cells, excitation consists of ‘transient’ and ‘sustained’ components and the ratio of transient/sustained components remains constant at a given retinal locus for a wide range of intensities. The transient component becomes proportionally larger towards the periphery of the receptive field. This rule is also applicable for the inhibitory and disinhibitory surround. In ‘transient’ cells, however, there is no true ‘sustained’ component, but some cells produce a double peaked transient post‐stimulus histogram at the R.F. centre when high flux stimuli are used, while others show a single peak transient response. The magnitude and shape of transient responses changes with intensity as well as with location in the receptive field. 3. The sensitivity gradients of ‘sustained’ and ‘transient’ cells show consistent differences in shape. The mean slope of the sensitivity gradients of a sample of ‘sustained’ cells was 10 times that of a sample of ‘transient’ cells. The sensitivity gradient of ‘sustained’ cells shows a distinct surround region where the inhibitory mechanism is more sensitive, while that of ‘transient’ cells usually does not, owing to an extensive ‘tail’ on the sensitivity gradient of the centre mechanism, which overlaps the surround. 4. Ricco's Law also holds for the centre mechanism of ‘transient’ cells. Non‐linear summation occurs at supra‐threshold levels, and when the surround mechanisms are involved. 5. Supra‐optimal stimuli give a saturation of the response in both ‘transient and ‘sustained’ cells. This saturation is associated with a decrease of latency in ‘transient’ cells, but not in ‘sustained’ cells. 6. The latency of retinal ganglion cells is determined by both stimulus and background flux. The effect of the background is negligible except at low values of stimulus flux, where its effect may be analysed primarily in terms of its effect on the incremental threshold. 7. The latency to stimulation with a standard small spot (25–27′) at the receptive field centre is shorter for ‘sustained’ cells than for ‘transient’ cells; this latency difference being related to the greater sensitivity of the ‘sustained’ cells to stimuli of this size. Differences in conduction time along ‘transient’ and ‘sustained’ pathways to the lateral geniculate nucleus (LGN) and cortex were estimated, and it is concluded that despite the latency difference noted above, a response to a stimulus which is optimal for a ‘transient’ cell reaches the cortex faster than the response to a stimulus which is optimal for a ‘sustained’ cell. 8. The above results together with previous evidence available suggest that for most stimuli, centre and surround mechanisms are activated simultaneously and algebraically su...

Abrupt changes in visual stimulation enhance processing of form and location information

“…As noted earlier, Breitmeyer and Ganz (1976) and Ikeda and Wright (1972) proposed that transient and sustained channels of the visual system might independently subserve the processing of location and figural information, respectively. This view would seem to predict that location accuracy should be higher in the form-change condition of the present experiment than in the no-form-change condition, owing to the abrupt stimulus change in the form-change condition which may activate the transient channel.…”

“…Physiological evidence suggests there may be two quite distinct subsystems within the visual system, one responsive to abrupt stimulus onsets or 0031-5117/83/120511-13$01.55/0 offsets (transient cells) and one responding in a steady-state manner to continuing stimulation (sustained cells). Breitmeyer and Ganz (1975) and Ikeda and Wright (1972) provide summaries of the properties of these subsystems found in cats and monkeys. Briefly, transient cells are characterized as having briefer onset latencies, shorter response durations, and poorer spatial resolution, and as being located primarily in the parafovea and periphery.…”

“…In contrast, the sustained cells have longer onset latencies, continuing responses throughout stimulation, and relatively good spatial resolution, and they are located primarily in the fovea. Given these different spatial, temporal, and distributional properties, Breitmeyer and Ganz (1976) and Ikeda and Wright (1972) suggested that the physiologically characterized transient channels would be well suited for coding the presenceand approximate location of moving or rapidly changing objects outside the fovea, and the sustained channels may carry information about the detailed figural properties of the visual stimulus, particularly if the stimulus is located in the foveal region. Todd and Van Gelder (1979) suggest that their finding of better performance in the onset condition than in the no-onset condition might be attributable to the greater involvement of transient channels in the onset condition.…”

Corollary discharge: Its possible implications in visual and oculomotor interactions

“…X type neurons might be devoted to the analysis of stationary visual features (e.g. form), while Y and W types would analyze movement [56,57]. Although most of this work has been carried out in the cat, a similar dichotomy is thought to exist in the monkey [58,59].…”

Suppression of visible persistence as a function of spatial separation between inducing stimuli

“…One way of increasing the period during which integration can occur is to increase the period that elapses between secondstimulus transient and first-stimulus sustained responses, as explained below. This was achieved in Experiment 2 by exploiting the relationship between stimulus intensity and response latency: given constant background luminance, a decrement in the intensity of a stimulus (i.e., a reduction in contrast) is known to produce a corresponding increment in the latencies of both transient and sustained responses (Ikeda & Wright, 1972;Shapley & Victor, 1978).…”