Regulation of synaptic timing in the olfactory bulb by an A-type potassium current.
Although rapid synaptic transmission confers signal fidelity, the activity of some neuronal circuits depends on prolonged excitation or inhibition. Here we demonstrate that GABAergic granule cells in the rat olfactory bulb produce prolonged inhibition of mitral cells through a precise kinetic matching between transmitter-gated and voltage-gated channels in their dendritic membrane. A transient A-type potassium current (IA) specifically attenuated dendrodendritic inputs mediated by fast-acting AMPA receptors such that the excitation and subsequent inhibitory output of granule cells followed the prolonged kinetics of their NMDA receptors. Altering the weights of the AMPA and NMDA receptor-mediated inputs by modulating IA provides a mechanism to regulate the timing of inhibition according to the demands on the bulb network.
Schoppa
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NE
Vollum Institute, Oregon Health Sciences University, 3181 SW Sam Jackson Park Road, Portland, Oregon 97201, USA. schoppan@ohsu.edu
Westbrook
G L
GL
D015761:4-Aminopyridine / Q000494:pharmacology; D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000818:Animals; D003712:Dendrites / Q000187:drug effects / Q000378:metabolism; D004558:Electric Stimulation; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects / Q000502:physiology; D005246:Feedback; D018698:Glutamic Acid / Q000378:metabolism; D066298:In Vitro Techniques; D015640:Ion Channel Gating / Q000187:drug effects; D007700:Kinetics; D009830:Olfactory Bulb / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D011188:Potassium / Q000378:metabolism*; D026902:Potassium Channel Blockers; D015221:Potassium Channels / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D018091:Receptors, AMPA / Q000037:antagonists & inhibitors / Q000502:physiology; D016194:Receptors, N-Methyl-D-Aspartate / Q000502:physiology; D026941:Sodium Channel Blockers; D015222:Sodium Channels / Q000378:metabolism; D013569:Synapses / Q000187:drug effects / Q000378:metabolism*; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology*; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
D018691:Excitatory Amino Acid Antagonists; D026902:Potassium Channel Blockers; D015221:Potassium Channels; D018091:Receptors, AMPA; D016194:Receptors, N-Methyl-D-Aspartate; D026941:Sodium Channel Blockers; D015222:Sodium Channels; D018698:Glutamic Acid; D005680:gamma-Aminobutyric Acid; D015761:4-Aminopyridine; D011188:Potassium