Visual abilities change over the visual field. For example, our ability to
detect movement is better in peripheral vision than in foveal vision, but c
olour discrimination is markedly worse(1,2). The deterioration of colour vi
sion has been attributed to reduced colour specificity in cells of the midg
et, parvocellular (PC) visual pathway in the peripheral retina(3-5). We hav
e measured the colour specificity (red-green chromatic modulation sensitivi
ty) of PC cells at eccentricities between 20 and 50 degrees in the macaque
retina. Here we show that most peripheral PC cells have red-green modulatio
n sensitivity close to that of foveal PC cells. This result is incompatible
with the view that PC pathway cells in peripheral retina make indiscrimina
te connections ('random wiring') with retinal circuits devoted to different
spectral types of cone photoreceptors(4,6,7). We show that selective cone
connections can be maintained by dendritic field anisotropy, consistent wit
h the morphology of PC cell dendritic fields in peripheral retina(8,9). Our
results also imply that postretinal mechanisms contribute to the psychophy
sically demonstrated deterioration of colour discrimination in the peripher
al visual field.