Properties of sustained and transient ganglion cells in the cat retina.

1. The functional basis for a sustained/transient classification of cat retinal ganglion cells has been strengthened by quantitative measurements of the sizes of the centre and surround components of receptive fields. Transient cells had larger surrounds than sustained; the distributions were non-overlapping. Although the distributions of centre sizes overlapped, the transient cells had very significantly larger centres on average.2. There were characteristic differences in area-threshold and annulus-threshold curves and shapes of responses to brief and long flashes of light, and relative differences in the nature of surround adaptation and maintained discharge rates.3. The distinction of sustained from transient units survived over a wide range of backgrounds including the two principle reorganizations of function: relative weakening of surround components at low background; Purkinje shift at high.4. Sustained and transient units were differentially distributed in the retina: there was an overwhelming preponderance of sustained units in the area centralis.5. It is proposed that the transient units are the so-called multidendritedeep cells and the sustained units are the variously styled small ganglion cells.