Abstract
The dentate gyrus is a prominent source of gamma frequency activity in the hippocampal formation in vivo. Here we show that transient epochs of gamma frequency network activity (67 +/- 12 Hz) can be generated in the dentate gyrus of rat hippocampal slices, following brief pressure ejections of a high-molarity potassium solution onto the molecular layer. Oscillatory activity remains synchronized over distances >300 microm and is accompanied by a modest rise in [K(+)](o). Gamma frequency oscillations were abolished by a GABA(A) receptor antagonist demonstrating their dependence on rhythmic inhibition. However, in many cases, higher frequency oscillations (>80 Hz) remained in the absence of synaptic transmission, thus demonstrating that nonsynaptic factors may underlie fast oscillatory activity.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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2-Amino-5-phosphonovalerate / pharmacology
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Anesthetics, Local / pharmacology
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Animals
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Bicuculline / pharmacology
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Dentate Gyrus / physiology*
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Excitatory Amino Acid Antagonists / pharmacology
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GABA Antagonists / pharmacology
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Membrane Potentials / drug effects
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Membrane Potentials / physiology
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Organ Culture Techniques
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Periodicity*
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Phosphinic Acids / pharmacology
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Potassium / pharmacology
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Propanolamines / pharmacology
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Quinoxalines / pharmacology
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Rats
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Rats, Wistar
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Tetrodotoxin / pharmacology
Substances
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Anesthetics, Local
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Excitatory Amino Acid Antagonists
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GABA Antagonists
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Phosphinic Acids
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Propanolamines
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Quinoxalines
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2,3-dioxo-6-nitro-7-sulfamoylbenzo(f)quinoxaline
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CGP 55845A
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Tetrodotoxin
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2-Amino-5-phosphonovalerate
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Potassium
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Bicuculline