RT Journal Article SR Electronic T1 Potentiation of L-Type Calcium Channels Reveals Nonsynaptic Mechanisms that Correlate Spontaneous Activity in the Developing Mammalian Retina JF The Journal of Neuroscience JO J. Neurosci. FD Society for Neuroscience SP 8514 OP 8522 DO 10.1523/JNEUROSCI.21-21-08514.2001 VO 21 IS 21 A1 J. H. Singer A1 R. R. Mirotznik A1 M. B. Feller YR 2001 UL http://www.jneurosci.org/content/21/21/8514.abstract AB Although correlated neural activity is a hallmark of many regions of the developing nervous system, the neural events underlying its propagation remain largely unknown. In the developing vertebrate retina, waves of spontaneous, correlated neural activity sweep across the ganglion cell layer. Here, we demonstrate that L-type Ca2+ channel agonists induce large, frequent, rapidly propagating waves of neural activity in the developing retina. In contrast to retinal waves that have been described previously, these L-type Ca2+ channel agonist-potentiated waves propagate independent of fast synaptic transmission. Bath application of nicotinic acetylcholine, AMPA, NMDA, glycine, and GABAAreceptor antagonists does not alter the velocity, frequency, or size of the potentiated waves. Additionally, these antagonists do not alter the frequency or magnitude of spontaneous depolarizations that are recorded in individual retinal ganglion cells. Like normal retinal waves, however, the area over which the potentiated waves propagate is reduced dramatically by 18α-glycyrrhetinic acid, a blocker of gap junctions. Additionally, like normal retinal waves, L-type Ca2+ channel agonist-potentiated waves are abolished by adenosine deaminase, which degrades extracellular adenosine, and by aminophylline, a general adenosine receptor antagonist, indicating that they are dependent on adenosine-mediated signaling. Our study indicates that although the precise spatiotemporal properties of retinal waves are shaped by local synaptic inputs, activity may be propagated through the developing mammalian retina by nonsynaptic pathways.