Hyperpolarizing responses to application of glutamate in hippocampal CA1 pyramidal neurons

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Micropressure injection of glutamate onto the apical dendrites of hippocampal CA1 pyramidal cells usually produces a fast rising, brief depolarization. However, hyperpolarizing responses with longer durations (300-500 ms) can be produced over a range of drug electrode locations. These hyperpolarizations can be reversed with intracellular injection of hyperpolarizing current. Localized application of glutamate in the stratum radiatum produces a depolarizing response in intracellularly recorded CA1 interneurons. Previous studies have shown that the dendrites of GABA-ergic basket cell interneurons extend into the stratum radiatum and are involved in mediating feedforward inhibition of pyramidal neurons. The glutamate-induced hyperpolarizations observed in pyramidal neurons are probably due to direct excitation of dendrites of interneurons, which in turn produce a synaptic inhibition in pyramidal cells.

Original languageEnglish (US)
Pages (from-to)85-90
Number of pages6
JournalNeuroscience Letters
Issue number1
StatePublished - Jul 9 1987
Externally publishedYes


  • Glutamate
  • Hippocampus
  • Hyperpolarization
  • Interneuron
  • Pyramidal cell

ASJC Scopus subject areas

  • Neuroscience(all)


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