AbstractSingle‐unit receptive fields were investigated in retinal‐ganglion‐cell axons to moving or flashing colored‐light spots. All of the cells were sensitive to moving stimuli; about 40% were directionally selective. Retinal‐ganglion‐cell axons in general had very low spontaneous activities. Most receptive fields had silent surround regions. These cells were usually most sensitive to red light, but when dark‐adapted, many cells also showed a high sensitivity to green and blue light. Under conditions of light adaptation, receptive fields to red light were little affected but receptive fields to green and blue lights disappeared. Fields were either circular, oval, or bar‐shaped. Adaptation, wavelength, and velocity affected the receptive field organization and response profiles. The mutability and complexity of receptive field organization, the presence of bar‐shaped fields and directionally selective cells, and multiple photoreceptor input to ganglion cells are indicative of retinas with particularly high integrative capacities, more so than in many
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