Abstract
Principal neurons of the medial nucleus of the trapezoid body (MNTB) receive a synaptic input from a single giant calyx terminal that generates a fast-rising, large excitatory postsynaptic current (EPSC), each of which are supra-threshold for postsynaptic action potential generation. Here, we present evidence that MNTB principal neurons receive multiple excitatory synaptic inputs generating slow-rising, small EPSCs that are also capable of triggering postsynaptic action potentials but are of non-calyceal origin. Both calyceal and non-calyceal EPSCs are mediated by alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA) and N-methyl-d-aspartate (NMDA) receptor activation; however, the NMDA receptor-mediated response is proportionally larger at the non-calyceal synapses. Non-calyceal synapses generate action potentials in MNTB principal neurons with a longer latency and a lower reliability than the large calyceal input. They constitute an alternative low fidelity synaptic input to the fast and secure relay transmission via the calyx of Held synapse.
MeSH terms
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Anesthetics, Local / pharmacology
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Animals
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Animals, Newborn
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Auditory Pathways / physiology*
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Brain Stem / cytology
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Brain Stem / physiology*
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Electric Stimulation
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Excitatory Amino Acid Agonists / pharmacology
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Excitatory Amino Acid Antagonists / pharmacology
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Excitatory Postsynaptic Potentials / drug effects
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Excitatory Postsynaptic Potentials / physiology
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In Vitro Techniques
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Membrane Potentials / drug effects
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Neurons / classification
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Neurons / drug effects
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Neurons / physiology*
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Patch-Clamp Techniques / methods
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Quinoxalines / pharmacology
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Rats
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Synaptic Transmission / drug effects
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Synaptic Transmission / physiology*
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Tetrodotoxin / pharmacology
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Time Factors
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Valine / analogs & derivatives*
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Valine / pharmacology
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alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid / pharmacology
Substances
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Anesthetics, Local
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Excitatory Amino Acid Agonists
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Excitatory Amino Acid Antagonists
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Quinoxalines
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2,3-dioxo-6-nitro-7-sulfamoylbenzo(f)quinoxaline
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Tetrodotoxin
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2-amino-5-phosphopentanoic acid
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alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid
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Valine