Facilitation at single synapses probed with optical quantal analysis

Nat Neurosci. 2002 Jul;5(7):657-64. doi: 10.1038/nn867.


Many synapses can change their strength rapidly in a use-dependent manner, but the mechanisms of such short-term plasticity remain unknown. To understand these mechanisms, measurements of neurotransmitter release at single synapses are required. We probed transmitter release by imaging transient increases in [Ca(2+)] mediated by synaptic N-methyl-D-aspartate receptors (NMDARs) in individual dendritic spines of CA1 pyramidal neurons in rat brain slices, enabling quantal analysis at single synapses. We found that changes in release probability, produced by paired-pulse facilitation (PPF) or by manipulation of presynaptic adenosine receptors, were associated with changes in glutamate concentration in the synaptic cleft, indicating that single synapses can release a variable amount of glutamate per action potential. The relationship between release probability and response size is consistent with a binomial model of vesicle release with several (>5) independent release sites per active zone, suggesting that multivesicular release contributes to facilitation at these synapses.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • 2-Chloroadenosine / pharmacology
  • Action Potentials / physiology
  • Animals
  • Calcium / analysis
  • Calcium / metabolism
  • Calcium Signaling / drug effects
  • Calcium Signaling / physiology
  • Electric Stimulation
  • Excitatory Postsynaptic Potentials / physiology
  • Glutamic Acid / metabolism
  • In Vitro Techniques
  • Neuronal Plasticity / physiology
  • Neurotransmitter Agents / metabolism*
  • Presynaptic Terminals / metabolism
  • Pyramidal Cells / drug effects
  • Pyramidal Cells / physiology*
  • Pyramidal Cells / ultrastructure
  • Rats
  • Receptors, N-Methyl-D-Aspartate / metabolism
  • Receptors, Purinergic P1 / metabolism
  • Sensory Thresholds / physiology
  • Synapses / drug effects
  • Synapses / metabolism
  • Synapses / physiology*


  • Neurotransmitter Agents
  • Receptors, N-Methyl-D-Aspartate
  • Receptors, Purinergic P1
  • 2-Chloroadenosine
  • Glutamic Acid
  • Calcium