Skip to main content

Advertisement

Dynamics of self-sustained microcircuits examined with regular-spiking readouts

Article metrics

  • 1794 Accesses

Analyzing the dynamics of large populations of neurons is a still a formidable challenge at present [1]. Even more so, beyond classical analysis techniques (correlation analysis, etc), characterizing the spatio-temporal trajectory of a neural system is very difficult. It has been suggested that such an endeavor can be made possible by describing the dynamics of the neuronal system through a state-space [2]. Such approaches have proven useful for odor decoding in honeybees [3], or the description of neuronal activity from monkey frontal areas [4]. There is however a fundamental problem for large neuronal systems: Finding of a relevant subset of variables that define a state, such that the subset preserves a reasonable amount of information about the whole system. Relevance is to be defined according to the observer of the neuronal population, which, in the real brain, consists of other neurons. Perhaps a good way to characterize a neuronal circuit is to use neuronal observers, and here, we show that a subset of neurons can be used to extract and compress information about the dynamics of a large self-sustained microcircuit. We used a population of 10 regular-spiking neurons as readouts, connected to all neurons of a self-sustained microcircuit containing ~600 Izhikevich type resonator neurons [5]. Synapses of each readout are excitatory, with long NMDA-like exponential decay of the synaptic conductance (30 ms). Synaptic strength for each individual synapse is computed as a sum of a fixed baseline (e.g. 0.7) and a smaller random fluctuation (e.g. between 0 and 0.2) drawn from a uniform distribution. The synaptic trees of the readouts are balanced: The total synaptic strengths are similar for each readout neuron. As a result, readouts fire with very similar rates, engaging into repeated temporal firing patterns, such that information can be recovered in the relative phase of their spike times (Fig 1). For each firing pattern, a phase vector is computed by calculating, for each readout, the time difference between its firing and that of the first readout (Fig. 1). As a result, a 10 dimensional vector of relative phases is computed, for each moment in time where a phase pattern occurs in the readout population. We show that the succession of these phase patterns can be used to characterize, in a compressed fashion, the dynamics of the whole microcircuit, including limit cycles.

Figure 1
figure1

Readouts from a microcircuit.

References

  1. 1.

    Brown EN, Kass RE, Mitra PP: Multiple neural spike train data analysis: state-of-the-art and future challenges. Nat Neurosci. 2004, 7 (5): 456-461. 10.1038/nn1228.

  2. 2.

    Brown EN, Barbieri R: Dynamic analyses of neural representations using the state-space modeling paradigm. The Cell Biology of Addiction. Edited by: Madras B, Von Zastrow M, Colvis C, Rutter J, Shurtleff D, Pollock J. 2005, New York, Cold Spring Harbor Laboratory Press, 415-432.

  3. 3.

    Galán RF, Sachse S, Galizia CG, Herz AV: Odor-driven attractor dynamics in the antennal lobe allow for simple and rapid odor classification. Neural Comput. 2004, 16 (5): 999-1012. 10.1162/089976604773135078.

  4. 4.

    Abeles M, Bergman H, Gat I, Meilijson I, Seidemann E, Tishby N, Vaadia E: Cortical activity flips among quasi-stationary states. Proc Natl Acad Sci USA. 1995, 92 (19): 8616-8620. 10.1073/pnas.92.19.8616.

  5. 5.

    Mureşan RC, Savin C: Resonance or integration? Self-sustained dynamics and excitability of neural microcircuits. J Neurophysiol. 2007, 97: 1911-1930. 10.1152/jn.01043.2006.

Download references

Acknowledgements

Research was supported by two grants of the Romanian Government: RP-5/2007, Contract 1/1.10.2007 and ID_48/2007, Contract Nr. 204/1.10.2007 financed by MECT/UEFISCSU and a Max Planck-Coneural Partner Group.

Author information

Correspondence to Raul C Mureşan.

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

Mureşan, R.C. Dynamics of self-sustained microcircuits examined with regular-spiking readouts. BMC Neurosci 9, P37 (2008) doi:10.1186/1471-2202-9-S1-P37

Download citation

Keywords

  • Firing Pattern
  • Neuronal System
  • Synaptic Strength
  • Spike Time
  • Phase Pattern