Transient and sustained types of long-term potentiation in the CA1 area of the rat hippocampus

J Physiol. 2003 Jul 15;550(Pt 2):459-92. doi: 10.1113/jphysiol.2003.044214. Epub 2003 Jun 6.


Synaptic potentiation induced by high frequency stimulation was investigated by recording field excitatory postsynaptic potentials (f-EPSPs) in rat hippocampal slices. Potentiation consisted of a transient period of decaying f-EPSPs (short-term potentiation, STP) that led to a plateau of continuously potentiated f-EPSPs (long-term potentiation, LTP). Here we show that a previously unknown type of transient, use-dependent, long-lasting potentiation (t-LTP) can account for STP. t-LTP could be stored for more than 6 h and its decay was caused by synaptic activation. Both the expression and the decay of t-LTP were input specific. t-LTP was induced differently from conventional LTP in that the amplitude of t-LTP was dependent upon the stimulation frequency, whereas the magnitude of LTP was dependent on the number of stimuli in the induction train. The decay of t-LTP could not be prevented by the blockage of glutamate receptors, but was prevented by the blockage of stimulus-evoked neurotransmitter release, suggesting that t-LTP is expressed presynaptically. Paired-pulse stimulation experiments showed that the decay of t-LTP was mediated by a decrease in the probability of neurotransmitter release. The decline of t-LTP could be prolonged by the activation of NMDA receptors. Hence, both single and paired-pulse stimuli prolonged the decline of the t-LTP. This decline could be prevented by high frequency burst stimulation (200 Hz). We conclude that t-LTP allows dynamic modulation of synaptic transmission by providing not only spatial association but also temporal convergence between synaptic inputs. Therefore, t-LTP might be a substrate for the encoding of synaptic memory.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 2-Amino-5-phosphonovalerate / pharmacology
  • Animals
  • Calcium / physiology
  • Electric Stimulation
  • Excitatory Amino Acid Antagonists / pharmacology
  • Excitatory Postsynaptic Potentials / physiology
  • Hippocampus / cytology
  • Hippocampus / physiology*
  • In Vitro Techniques
  • Long-Term Potentiation / physiology*
  • Magnesium / pharmacology
  • Male
  • Membrane Potentials / physiology
  • Neurons / physiology*
  • Neurotransmitter Agents / metabolism
  • Patch-Clamp Techniques
  • Rats
  • Rats, Wistar
  • Receptors, N-Methyl-D-Aspartate / agonists
  • Receptors, N-Methyl-D-Aspartate / physiology
  • Synapses / physiology


  • Excitatory Amino Acid Antagonists
  • Neurotransmitter Agents
  • Receptors, N-Methyl-D-Aspartate
  • 2-Amino-5-phosphonovalerate
  • Magnesium
  • Calcium