Receptive Field Properties of Starburst Cholinergic Amacrine Cells in the Rabbit Retina

Patch‐clamp recordings were made from ON starburst cholinergic amacrine cells with somas located in the ganglion cell layer of an isolated, dark‐adapted rabbit retina preparation. Light responses were analysed and cell identity was confirmed anatomically. The centre light response had a linear current‐voltage relation with a reversal potential close to 0 mV. The receptive field size was similar to the dendritic field size. Cholinergic amacrine cells displayed significant surround inhibition. The receptive field profile consisted of a central excitatory region flanked by an inhibitory surround. The surround attenuated the central response to 36% of the maximum. The surround was probably mediated by a combination of presynaptic and postsynaptic inhibition. Starburst amacrine cells did not display action potentials and the presence of a large, voltage‐dependent outward current limited depolarizing responses to a maximum potential of about ‐40 mV. Light responses were completely suppressed during application of 100 μM D, L‐2‐amino‐4‐phosphonobutyric acid (APB), consistent with activation exclusively through rod bipolar cells (on) and ON‐cone bipolar cells. In darkness the cells displayed a tonic inward current that could be blocked by 100 μM APB and 2 μM CNQX.