Research Article

Expression of long-term potentiation in aged rats involves perforated synapses but dendritic spine branching results from high-frequency stimulation alone

  1. Tiruchinapalli M. Dhanrajan1,
  2. Marina A. Lynch2,
  3. Aine Kelly2,
  4. Victor I. Popov1,3,
  5. Dmitri A. Rusakov1,4,
  6. Michael G. Stewart1,*

Article first published online: 12 FEB 2004

DOI: 10.1002/hipo.10172

Issue

Hippocampus

Hippocampus

Volume 14, Issue 2, pages 255–264, 2004

Additional Information

How to Cite

Dhanrajan, T. M., Lynch, M. A., Kelly, A., Popov, V. I., Rusakov, D. A. and Stewart, M. G. (2004), Expression of long-term potentiation in aged rats involves perforated synapses but dendritic spine branching results from high-frequency stimulation alone. Hippocampus, 14: 255–264. doi: 10.1002/hipo.10172

Author Information

  1. 1

    Department of Biological Sciences, The Open University, Milton Keynes, United Kingdom

  2. 2

    Department of Physiology, Trinity College, Dublin, Ireland

  3. 3

    Institute of Cell Biophysics, Russian Academy of Sciences, Pushchino, Russia

  4. 4

    Institute of Neurology, University College London, London, United Kingdom

*Department of Biological Sciences, The Open University, Milton Keynes, MK7 6AA, UK

Publication History

  1. Issue published online: 9 MAR 2004
  2. Article first published online: 12 FEB 2004
  3. Manuscript Accepted: 11 APR 2003

Funded by

  • Biological and Biotechnology Research Council (BBSRC). Grant Number: 108/BI 11211
  • Leverhulme Trust. Grant Number: F00269G
  • Russian Foundation for Basic Research (RFBR). Grant Number: 02-04-48890a

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Keywords:

  • perforated synapses;
  • branched spines;
  • LTP

Abstract

Evidence for morphological substrates of long-term changes in synaptic efficacy is controversial, partly because it is difficult to employ an unambiguous control. We have used a high-frequency stimulation protocol in vivo to induce long-term potentiation (LTP) in the hippocampal dentate gyrus of aged (22-month-old) rats and have found a clear distinction between animals that sustain LTP and those that fail to sustain it. The “failure group” was used as a specific/“like-with-like” control for morphological changes associated with the expression of LTP per se. Quantitative optical and electron microscopy was used to analyze large populations of dendritic spines and excitatory perforant path synapses; LTP was found to be associated with an increase in numbers of segmented (perforated) postsynaptic densities in spine synapses. In contrast, an increase in the number of branched spines appears to result from high-frequency stimulation alone. These data shed light on the current controversy about the expression mechanism of LTP. © 2004 Wiley-Liss, Inc.

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