Centre and surround influences on the proximal negative response of the pigeon retina.

1. Extracellular field potentials were recorded with micro-electrodes in the inner plexiform layer of the pigeon retina. Stimulus patterns were projected on a tangent screen.2. Maximal responses to a 1 degrees spot were produced from a receptive area 2-3 degrees in extent. Annuli centred over this area produced a different response wave form.3. The responses to centred spots and annuli presented synchronously do not superpose: they interact in a way suggesting transient mutual antagonism. The response to spot onset and offset can be suppressed either by annulus onset or by annulus offset.4. A steady annulus has little effect on the response to spot stimuli, but a steady centred spot enhances the response to annular stimulation.5. The results suggest that the PNR results from convergence of on-centre and off-centre pathways, which are embedded in a widespread suppressive surround.