Temporal limits on the rise in postsynaptic calcium required for the induction of long-term potentiation

Neuron. 1992 Jul;9(1):121-8. doi: 10.1016/0896-6273(92)90227-5.


The induction of long-term potentiation (LTP) in hippocampal CA1 pyramidal cells requires a rise in postsynaptic intracellular Ca2+ concentration ([Ca2+]i). To determine the time for which Ca2+ must remain elevated to induce LTP, the photolabile Ca2+ buffer diazo-4 was used to limit the duration of the rise in postsynaptic [Ca2+]i following a tetanus. The affinity of diazo-4 for Ca2+ increases approximately 1600-fold upon flash photolysis, permitting almost instantaneous buffering of [Ca2+]i without disturbing resting [Ca2+]i prior to the flash. Photolysis of diazo-4 1 s following the start of the tetanus blocked LTP, while delaying photolysis for more than 2 s had no discernible effect on LTP. Photolyzing diazo-4 at intermediate delays (1.5-2 s) or reducing photolysis of diazo-4 often resulted in short-term potentiation (STP). These results indicate that a tetanus-induced rise in postsynaptic [Ca2+]i lasting at most 2-2.5 s is sufficient to generate LTP. Smaller increases or shorter duration rises in [Ca2+]i may result in STP.

Publication types

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

MeSH terms

  • Action Potentials / physiology*
  • Animals
  • Calcium / analysis
  • Calcium / physiology*
  • Cells, Cultured
  • Hippocampus / chemistry
  • Hippocampus / cytology
  • Hippocampus / physiology
  • Photolysis
  • Rats
  • Rats, Inbred Strains
  • Synapses / chemistry
  • Synapses / physiology*
  • Time Factors


  • Calcium