Rod pathways in the retina of the cat

Neurons involved in the transfer of rod signals to the ganglion cells in the retina of the cat have been recorded from and stained with horseradish peroxidase (HRP) and their synaptic connections determined by electron microscopy. The single morphological type of rod bipolar cell responds with a sustained hyperpolarization to light and in turn drives at least five morphologically different types of amacrine cells, each of which has a unique response pattern. Two amacrines respond with either a transient (AII) or a sustained (A17) depolarization to light, while three amacrines give transient (A8) or sustained (A6, A13) hyperpolarizations. Circuitry whereby rod signals reach both on-centre and off-centre ganglion cells is discussed.