Abstract
Pharmacologically isolated starburst amacrine cells (SACs) in perinatal rabbit retinas spontaneously generated semiperiodic calcium spikes and long-lasting after-hyperpolarizations (AHPs), mediated by calcium-activated, cyclic AMP-sensitive potassium currents. These AHPs, rather than a depletion of neurotransmitters (as was previously believed), produced the refractory period of spontaneous retinal waves and set the upper limit of the wave frequency. Each SAC received inputs from roughly 10-30 neighboring SACs during a wave. These inputs synchronized and reshaped the intrinsic bursts to produce network oscillations at a rhythm different from that of individual SACs. With maturation, the semiperiodic bursts in SACs disappeared, owing to reduced intrinsic excitability and increased network inhibition. Thus, retinal waves are generated by a transient and specific network of cell-autonomous oscillators synchronized by reciprocally excitatory connections.
Publication types
-
Research Support, N.I.H., Extramural
-
Research Support, Non-U.S. Gov't
MeSH terms
-
Action Potentials / drug effects
-
Action Potentials / physiology*
-
Amacrine Cells / cytology
-
Amacrine Cells / drug effects
-
Amacrine Cells / physiology*
-
Animals
-
Biological Clocks / drug effects
-
Biological Clocks / physiology*
-
Calcium / metabolism
-
Calcium Signaling / drug effects
-
Calcium Signaling / physiology
-
Fura-2 / analogs & derivatives
-
In Vitro Techniques
-
Isoquinolines
-
Nerve Net / cytology
-
Nerve Net / drug effects
-
Nerve Net / physiology*
-
Patch-Clamp Techniques
-
Potassium Channels, Calcium-Activated / drug effects
-
Potassium Channels, Calcium-Activated / metabolism
-
Rabbits
-
Retinal Ganglion Cells / cytology
-
Retinal Ganglion Cells / drug effects
-
Retinal Ganglion Cells / physiology
-
Synaptic Transmission / drug effects
-
Synaptic Transmission / physiology*
-
Vision, Ocular / physiology
-
Visual Pathways / cytology
-
Visual Pathways / drug effects
-
Visual Pathways / physiology*
Substances
-
Isoquinolines
-
Potassium Channels, Calcium-Activated
-
fura-2-am
-
lucifer yellow
-
Calcium
-
Fura-2