The spatiotemporal building blocks of X-, Y- and W-ganglion cell receptive fields of the cat's retina.

The spatiotemporal distribution of excitation and inhibition has been characterized in 283 X-, Y- and W- cat retinal ganglion cells. Cells were classified by their latency from optic chiasm stimulation, responses to moving bars and gratings and responses to flashed gratings. As expected from earlier LGN studies the responses of retinal X-cells and Y-cells had distinct spatiotemporal profiles. The Y-cells had a relatively constant or homogeneous spatial distribution of responses while X-cells had a heterogeneous spatial arrangement. As has been previously reported in LGN, retinal X- and Y-fields had four independent spatiotemporal components or response domains; primary excitation (PE), primary inhibition (PI), secondary excitation (SE) and, finally, secondary inhibition (SI). In contrast, W-receptive fields had a few as a single response domain or as many as eight. An unexpected discovery was that all of these W-receptive fields were constructed from spatiotemporal domains, identical to those found in X-receptive fields. Thus, taking on-center and off-center cells into account we have found a total of 16 different spatiotemporal response components or "building blocks" for X- and Y-cells and the X-building blocks appear to be used in the construction of W-receptive fields.