Abstract
The number of vesicles released at excitatory synapses and the number of release sites per synaptic connection are key determinants of information processing in the cortex, yet they remain uncertain. Here we show that the number of functional release sites and the number of anatomically identified synaptic contacts are equal at connections between spiny stellate and pyramidal cells in rat barrel cortex. Moreover, our results indicate that the amount of transmitter released per synaptic contact is independent of release probability and the intrinsic release probability is high. These properties suggest that connections between layer 4 and layer 2/3 are tuned for reliable transmission of spatially distributed, timing-based signals.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Action Potentials
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Analysis of Variance
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Animals
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Axons / physiology
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Axons / ultrastructure
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Calcium / pharmacology
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Dendrites / physiology
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Dendrites / ultrastructure
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Dipeptides / pharmacology
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Excitatory Amino Acid Antagonists / pharmacology
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Excitatory Postsynaptic Potentials / drug effects
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Glutamic Acid / metabolism
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Image Processing, Computer-Assisted
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In Vitro Techniques
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Kynurenic Acid / pharmacology
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Lysine / analogs & derivatives*
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Patch-Clamp Techniques
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Probability
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Pyramidal Cells / physiology
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Rats
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Rats, Wistar
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Receptors, Glutamate / metabolism
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Somatosensory Cortex / cytology
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Somatosensory Cortex / physiology*
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Synapses / physiology*
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Synaptic Transmission / physiology*
Substances
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Dipeptides
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Excitatory Amino Acid Antagonists
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Receptors, Glutamate
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gamma-glutamylglycine
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Glutamic Acid
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biocytin
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Kynurenic Acid
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Lysine
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Calcium