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: Eighteenth Annual Computational Neuroscience Meeting: CNS*2009

Open Access Poster presentation

Implications of the specific cortical circuitry for the network dynamics of a layered cortical network model

Tobias C Potjans12*, Tomoki Fukai13 and Markus Diesmann134

Author Affiliations

1 Brain and Neural Systems Team, RIKEN Computational Science Research Program, Wako City, Saitama, Japan

2 Institute of Neurosciences and Medicine, Research Center Jülich, Jülich, Germany

3 Theoretical Neuroscience Group, RIKEN Brain Science Institute, Wako City, Saitama, Japan

4 Bernstein Center for Computational Neuroscience, Albert-Ludwigs University, Freiburg, Germany

For all author emails, please log on.

BMC Neuroscience 2009, 10(Suppl 1):P159  doi:10.1186/1471-2202-10-S1-P159


The electronic version of this article is the complete one and can be found online at: http://www.biomedcentral.com/1471-2202/10/S1/P159


Published:13 July 2009

© 2009 Potjans et al; licensee BioMed Central Ltd.

Poster presentation

The local cortical network consists of specifically interconnected neuronal populations (see [1] for review). This microcircuitry determines the possible interactions between neurons and thus may play a crucial role in shaping neuronal activity. We investigate the dynamical implications of the specificity of connections in the local network by means of large-scale simulations [2] of a spiking layered network model. To this end, we quantify the specificity of connections measured by diverse experimental techniques.

We identify a hierarchy of specificity (Figure 1): Layer-specific connections (A) depend on the layers of the pre- and post-synaptic populations. Among the most prominent layer-specific connection profiles is a feed-forward pattern of connections (layer 4 (L4) to L2/3 to L5 to L6) which is closely linked to the tuning properties of cells in the primary visual cortex [1]. Target-specific connections (B), in addition, depend on the neuronal type of the target neuron [3]. Projection-specificity (C), finally, classifies neuronal subpopulations of a layer according to the main target layer of their axonal projection (see [4] for review).

thumbnailFigure 1. The hierarchy of specificity in the layered cortical network model.

Our layered cortical network model consists of 80,000 I&F neurons and explains about 90% of the synapses constituting the local cortical microcircuit. As we focus on the relationship of connectivity and network activity, we use identical dynamics and parameters for all neuron types in the network. Despite this homogeneity, we observe that the layer specific connections alone cause layer- and type-specific firing rates: excitatory firing rates are lowest in L2/3 (often below 1 Hz, comparable to [5]) and highest in L5 and inhibitory firing exceeds excitatory rates. Furthermore we find that a small subset of target-specific connections [3] is relevant for the stability of network activity. Finally, the incorporation of projection-specificity enables us to investigate the influence of fine-scale connectivity on global activity patterns. We conclude that specific connections represent a structural correlate of the experimentally observed network dynamics.

Acknowledgements

Partially funded by EU Grant 15879 (FACETS), BMBF Grant 01GQ0420 to BCCN Freiburg, Next-Generation Supercomputer Project of MEXT, Japan, and the Helmholtz Alliance on Systems Biology.

References

  1. Douglas RJ, Martin KAC: Neuronal circuits of the neocortex.

    Annu Rev Neurosci 2004, 27:419-451. PubMed Abstract | Publisher Full Text OpenURL

  2. Gewaltig M-O, Diesmann M: NEST (neural simulation tool).

    Scholarpedia 2007, 2:1430. OpenURL

  3. Potjans TC, Diesmann M: Consistency of in vitro and in vivo connectivity estimates: statistical assessment and application to cortical network modeling.

    38th Soc for Neurosci Meeting 2008, 16:1. OpenURL

  4. Thomson AM, Lamy C: Functional maps of neocortical local circuitry.

    Front Neurosci 2007, 1:1-42. Publisher Full Text OpenURL

  5. Greenberg DS, Houweling AR, Kerr JND: Population imaging of ongoing neuronal activity in the visual cortex of awake rats.

    Nat Neurosci 2008, 11:749-751. PubMed Abstract | Publisher Full Text OpenURL