MLA-sensitive cholinergic receptors involved in the detection of complex moving stimuli in retina.

Acetylcholine, acting through nicotinic acetylcholine receptors, mediates the response properties of many ganglion cells in the rabbit retina, including those that are directionally selective (DS; Ariel & Daw, 1982a, b). For example, Grzywacz et al. (1998) showed that cholinergic input is necessary for DS responses to drifting gratings, a form of textured stimulus. However, the identities and locations of the neuronal acetylcholine receptor (nAChR) subtypes that mediate this input are not clear (Keyser et al., 2000). We investigated the role of methyllycaconitine-sensitive, alpha7-like nAChRs in mediating DS responses to textured stimuli and apparent motion. We recorded extracellularly from On-Off DS ganglion cells in rabbit retina using everted eyecup preparations. Our data provide evidence that MLA-sensitive nAChRs are involved in mediating directionally selective responses to apparent motion and to a variety of complex, textured stimuli such as drifting square-wave gratings, transparent motion, and second-order motion.