Final answer:
On-center ganglion cells hyperpolarize in response to light, which leads to the creation of on-center action potentials because of the disinhibition of bipolar cells.
Step-by-step explanation:
In response to light, the on-center ganglion cells will hyperpolarize, which removes the inhibition of the bipolar cells by photoreceptors (rods and cones). As a result of the light-induced hyperpolarization of the photoreceptors, these bipolar cells in turn activate the ganglion cells and create on-center action potentials. The horizontal cells create lateral inhibition which sharpens the contrast, making light regions appear lighter and dark surroundings appear darker, but this is orthogonal to the initial activation process of ganglion cells.