The findings from this study on cone-mediated pathways provide insights into the mechanisms underlying transient and sustained responses in rod-mediated pathways in the retina. While this study focused on the parallel ON pathways driven by cone photoreceptors, similar principles likely apply to the rod-mediated pathways that operate under dim light conditions. Rod bipolar cells, which transmit signals from rod photoreceptors to RGCs, are also known to exhibit transient or sustained response properties based on their synaptic inputs and intrinsic properties.
In rod-mediated pathways, differences in the kinetics of glutamate release from rod bipolar cells could contribute to the generation of transient or sustained responses in downstream RGCs. Similar to cone bipolar cells, rod bipolar cells may exhibit subtype-specific differences in synaptic vesicle dynamics, ribbon size, or presynaptic modulation that shape the temporal characteristics of excitatory inputs to RGCs. Understanding the mechanisms that govern transient and sustained signaling in rod pathways could parallel the findings from cone pathways and provide a comprehensive view of how visual information is processed in the retina under different lighting conditions.