Properties of the receptive fields of frog retinal ganglion cells as revealed by their response to moving stimuli.

Quantitative mapping of the excitatory receptive fields of frog retinal ganglion cells revealed that the precise spatial position and locus of maximal activity within the excitatory receptive field were dependent upon the exact sequence with which the moving stimulus scanned the region of visual space in which the excitatory receptive field was embedded. A first-order asymmetry dependent upon the direction from which the moving stimulus entered the excitatory receptive field was noted. A second-order asymmetry, orthogonal to the first and sensitive to the direction in which a moving stimulus systematically traversed successive columns with in the excitatory receptive field was also described. These findings indicate that complicated interactions, both excitatory and inhibitory, occur between component parts of the receptive field in the frog retina.