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The information efficacy of a synapse

Nature Neuroscience volume 5, pages 332–340 (2002)Cite this article

Abstract

We provide a functional measure, the synaptic information efficacy (SIE), to assess the impact of synaptic input on spike output. SIE is the mutual information shared by the presynaptic input and postsynaptic output spike trains. To estimate SIE we used a method based on compression algorithms. This method detects the effect of a single synaptic input on the postsynaptic spike output in the presence of massive background synaptic activity in neuron models of progressively increasing realism. SIE increased with increases either in time locking between the input synapse activity and the output spike or in the average number of output spikes. SIE depended on the context in which the synapse operates. We also measured SIE experimentally. Systematic exploration of the effect of synaptic and dendritic parameters on the SIE offers a fresh look at the synapse as a communication device and a quantitative measure of how much the dendritic synapse informs the axon.

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Figure 1: Single dendritic synapses, among many other synapses, do matter.
Figure 2: MI as a measure of synaptic efficacy.
Figure 3: Effect of EPSP shape indices on the SIE.
Figure 4: SIE is context dependent.
Figure 5: Effect of dendritic input location on the SIE.
Figure 6: SIE in nonlinear dendrites.
Figure 7: Experimental measurements of the SIE.

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Acknowledgements

The authors thank R. El-Yaniv for his help in developing the entropy estimation method. This work was supported by grants from the ONR, NIMH, the US-Israel BSF, the Israel Science Foundation and the Wellcome Trust.

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Authors and Affiliations

  1. Department of Neurobiology Institute of Life Sciences and Center for Neural Computation, Hebrew University, Jerusalem, 91904, Israel

    Michael London & Idan Segev

  2. Department of Computer Science, Hebrew University, Jerusalem, 91904, Israel

    Adi Schreibman

  3. Department of Physiology, University College London, Gower Street, London, WC1E 6BT, UK

    Michael Häusser

  4. Abteilung Zellphysiologie, Max-Planck-Institut für medizinische Forschung, Jahnstraβe 29, Heidelberg, D-69120, Germany

    Matthew E. Larkum

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Correspondence to Idan Segev.

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London, M., Schreibman, A., Häusser, M. et al. The information efficacy of a synapse. Nat Neurosci 5, 332–340 (2002). https://doi.org/10.1038/nn826

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