Skip to main content

Advertisement

Shaping of STDP curve by interneuron and Ca2+dynamics

Article metrics

  • 998 Accesses

Spike-timing-dependent-plasticity (STDP)[1, 2] is a special form of Hebbian learning [3] where the relative timing of post- and presynaptic activity determines the change in synaptic weight. More familiarly, the postsynaptic and presynaptic activity correspond respectively to the derivative of the membrane potential Vm and the NMDA channel activation [4]. We present a model where the postsynaptic activity is modelled by the derivative of the Ca2+ concentration. Using a model of a pyramidal cell, attached interneuron and detailed Ca2+ dynamics, we show that the classical STDP curve is greatly altered, in particular, that long term depression (LTD) is markedly reduced [5] while LTP remains close to the original expected weight-change curve. In addition to this we have shown that by reducing the NMDA activity in the circuit model there is a noticeable change in the LTD/LTP magnitude in the STDP weight-change curve. This modification causes two effects; it reduces plasticity in the excitatory neuron but also reduces inhibition on the excitatory neuron. Therefore we show that by decreasing NMDA activity there is a clear reduction in LTD and LTP. This appears much like the "classical" STDP curve albeit scaled down in ratio to the reduced NMDA activity. In this study we have shown that the inhibitory interneuron reduces the LTD part of the STDP weight change curve. The more inhibition seen, the less LTD in the excitatory neuron. Thus, a hypofunction of inhibitory neurons will lead to more LTD in cortical structures and ultimately to less cortical activity. This hypofunction could be a possible mechanism of how administration of the NMDA antagonist PCP causes cortical hypoactivity[6] after a time lapse of a few days, and is already a topic of interest in the research of schizophrenia.

References

  1. 1.

    Magee JC, Johnston D: A synaptically controlled, associative signal for Hebbian plasticity in hippocampal neurons. Science. 1997, 275: 209-213. 10.1126/science.275.5297.209.

  2. 2.

    Markram H, Lübke J, Frotscher M, Sakmann B: Regulation of synaptic efficacy by coincidence of postsynaptic Aps and EPSPs. Science. 1997, 275: 213-215. 10.1126/science.275.5297.213.

  3. 3.

    Hebb DO: The organization of behaviour: A neuropsychological study. 1949, Wiley Interscience, New York

  4. 4.

    Porr B, Saudargiene A, Wörgötter F: Analytical solution of spike-timing dependent plasticity based on synaptic biophysics. Advances in neural information processing systems, 16. 2004, Cambridge MA: MIT Press

  5. 5.

    Aihara Y, Abiru Y, Yamazaki Y, Wantanbe H, Fukushima Y, Tsukada M: The relation between spike-timing dependent plasticity and Ca2+ dynamics in the hippocampal CA1 network. Neuroscience. 2007, 145: 80-87. 10.1016/j.neuroscience.2006.11.025.

  6. 6.

    Morris BJ, Cochran SM, Pratt JA: PCP: from pharmacology to modelling schizophrenia. Current Opinion in Pharmacology. 2005, 5: 101-106. 10.1016/j.coph.2004.08.008.

Download references

Author information

Correspondence to Lynsey McCabe.

Rights and permissions

Open Access This article is published under license to BioMed Central Ltd. This is an Open Access article is distributed under the terms of the Creative Commons Attribution 2.0 International License (https://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Reprints and Permissions

About this article

Cite this article

McCabe, L., Di Prodi, P., Porr, B. et al. Shaping of STDP curve by interneuron and Ca2+dynamics. BMC Neurosci 8, P83 (2007) doi:10.1186/1471-2202-8-S2-P83

Download citation

Keywords

  • Schizophrenia
  • Pyramidal Cell
  • Circuit Model
  • Time Lapse
  • Synaptic Weight