retinal convergencethe sharing of a single nerve fibre by several rods in the retina of the vertebrate EYE. The rods share or converge into one nerve fibre (see Fig. 269 ). Rods are used particularly in low illumination when the stimulus of light on a single rod may be insufficient to generate an ACTION POTENTIAL in the NEURONE. However, the stimulus of several rods on one neurone will excite it more easily, and six rods stimulated together will fire a neurone. This is an example of SUMMATION. Cones show little or no retinal convergence.
Collins Dictionary of Biology, 3rd ed. © W. G. Hale, V. A. Saunders, J. P. Margham 2005