Abstract
Abstract: :
Purpose: To investigate the effect of the cholinergic outputs of the starburst amacrine cells on the direction selective ganglion cells of rabbit retina. Methods: Two spot apparent motion protocols were used. The first spot was placed just outside the ganglion cell’s receptive field. PTX and curare were used to selectively block GABAergic inhibition or cholinergic excitation. Results: Under control conditions, facilitation in the preferred direction was confirmed (Amthor et al., Vis. Neurosci. 13:303-309, 1996). Upon removal of inhibition by PTX, facilitation was also observed for null direction sequences. Facilitation in either direction was eliminated by curare. Conclusion: Cholinergic, feed forward, facilitation occurs in both the preferred and null directions. This indicates that the cholinergic output of the starburst cells is not direction selective. If the starburst cells participate in the directional decision (Yoshida et al., Neuron. 30:771-780, 2001), they may do so via their GABAergic synapses.
Keywords: 559 retinal connections, networks, circuitry • 415 ganglion cells • 312 amacrine cells