Long-lasting intrinsic persistent firing in rat CA1 pyramidal cells: a possible mechanism for active maintenance of memory

Hippocampus. 2013 Sep;23(9):820-31. doi: 10.1002/hipo.22136. Epub 2013 Jun 3.

Abstract

The hippocampus is critical for memory tasks which require an active maintenance of memory for a short period of time; however, the underlying neural mechanisms remain unknown. Most theoretical and computational models, which date back to the classic proposals by Donald Hebb in , have been self-constrained by anatomy, as most models rely on the recurrent connectivity in region CA3 to support "reverberating activity" capable of memory maintenance. However, several physiological and behavioral studies have specifically implicated region CA1 in tasks which require an active maintenance of memory. Here, we demonstrate that despite limited recurrent connectivity, CA1 contains a robust cellular mechanism for active memory maintenance in the form of self-sustained persistent firing. Using in vitro whole-cell recordings, we demonstrate that brief stimulation (0.2-2 s) reliably elicits long-lasting (> 30 s) persistent firing that is supported by the calcium-activated non-selective cationic current. In contrast to more traditional ideas, these data suggest that the hippocampal region CA1 is capable of active maintenance of memory.

Keywords: CAN current; information retention; learning and memory; mAChR; whole-cell patch clamp.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Action Potentials / drug effects
  • Action Potentials / physiology*
  • Animals
  • Animals, Newborn
  • CA1 Region, Hippocampal / cytology*
  • Carbachol / pharmacology
  • Cholinergic Agonists / pharmacology
  • Electric Stimulation
  • Excitatory Amino Acid Agonists / pharmacology
  • Excitatory Amino Acid Antagonists / pharmacology
  • Female
  • GABA-A Receptor Antagonists / pharmacology
  • Glutamic Acid / pharmacology
  • In Vitro Techniques
  • Kynurenic Acid / pharmacology
  • Male
  • Picrotoxin / analogs & derivatives
  • Picrotoxin / pharmacology
  • Pyramidal Cells / drug effects
  • Pyramidal Cells / physiology*
  • Rats
  • Rats, Long-Evans
  • Time Factors

Substances

  • Cholinergic Agonists
  • Excitatory Amino Acid Agonists
  • Excitatory Amino Acid Antagonists
  • GABA-A Receptor Antagonists
  • Picrotoxin
  • Glutamic Acid
  • Carbachol
  • picrotoxinin
  • Kynurenic Acid