Email updates

Keep up to date with the latest news and content from BMC Neuroscience and BioMed Central.

This article is part of the supplement: Sixteenth Annual Computational Neuroscience Meeting: CNS*2007

Open Access Poster presentation

Shaping of STDP curve by interneuron and Ca2+ dynamics

Lynsey McCabe1*, Paolo Di Prodi1, Bernd Porr1 and Florentin Wörgötter2

Author Affiliations

1 Department of Electronics and Electrical Engineering, University of Glasgow, Glasgow G12 8LT, UK

2 Bernstein Center for Computational Neuroscience, University of Göttingen, Bunsenstr. 10 (at the MPI), D-37073 Göttingen, Germany

For all author emails, please log on.

BMC Neuroscience 2007, 8(Suppl 2):P83  doi:10.1186/1471-2202-8-S2-P83


The electronic version of this article is the complete one and can be found online at:


Published:6 July 2007

© 2007 McCabe et al; licensee BioMed Central Ltd.

Poster presentation

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. Magee JC, Johnston D: A synaptically controlled, associative signal for Hebbian plasticity in hippocampal neurons.

    Science 1997, 275:209-213. PubMed Abstract | Publisher Full Text OpenURL

  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. PubMed Abstract | Publisher Full Text OpenURL

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

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

  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. PubMed Abstract | Publisher Full Text OpenURL

  6. Morris BJ, Cochran SM, Pratt JA: PCP: from pharmacology to modelling schizophrenia.

    Current Opinion in Pharmacology 2005, 5:101-106. PubMed Abstract | Publisher Full Text OpenURL