Skip to main content
  • Featured talk presentation
  • Open access
  • Published:

Network community, clusters and hubs in cortical micro circuits

Networks of cortical neurons are essentially non-random [1]. Although it is known that such networks show interesting structure at multiple temporal and spatial scales [2], almost no experimental work has been done to reveal how structures at these different scales relate to each other.

This study aimed to clarify important relations between non-randomness in groups of 3-6 neurons (clusters) and non-randomness in groups of 50-100 neurons (communities) through five steps. First, we recorded spontaneous activity of up to 500 neurons from rodent somatosensory cortex using a 512ch. multi-electrode system over one hour [3]. Second, we reconstructed effective connectivity using transfer entropy [4]. Third, we compared topologies of effective networks at the 3-6 neuron scale (clusters including motifs [Figure1-B]) with topologies of synaptic connections measured from 12 neuron simultaneous patch clamp experiments [5, 6]. Fourth, we constructed community or modular structures representing non-randomness from larger groups of neurons. Fifth, we evaluated the extent to which structure at each of these scales was robust. We did this by swapping connections from high degree nodes (hubs) with those from low degree nodes (non-hubs).

We found three things. First, the degree-distribution followed a power-law This demonstrated that hubs could not have been the result of random sampling from a Gaussian distribution. Second, effective networks consisting of hundreds of cortical neurons have distinctive non-random structures of connectivity at two different scales. Third, structure at the cluster level was relatively more fragile than structure at the community level. The difference between non-randomness evaluated by cluster and community will become the important first step to understand multiple different scales of cortical neuronal networks.

Figure 1
figure 1

(A) An example of spatial distribution of neurons and effective connections. Different markers indicate different communities. The biggest two communities are covered by blue and red regions. Upper-right yellow region is an example cluster of 6 neurons. (B) Examples of clusters of 3-6 neurons. (C) An illustration of community structures. Connections are relatively denser among neurons within each community and sparser between neurons in different communities.


  1. Song S, Sjöström PJ, Reigl M, Nelson S, Chklovskii DB: Highly nonrandom features of synaptic connectivity in local cortical circuits. PLoS Biology. 2005, 3 (3): e68-10.1371/journal.pbio.0030068.

    Article  PubMed Central  PubMed  Google Scholar 

  2. Buzsáki G, Geisler C, Henze DA, Wang XJ: Interneuron Diversity series: Circuit complexity and axon wiring economy of cortical interneurons. TRENDS in Neurosciences. 2004, 27 (4): 186-193. 10.1016/j.tins.2004.02.007.

    Article  PubMed  Google Scholar 

  3. Litke AM, et al: What does the eye tell the brain?: Developent of a system for the large-scale recording of retinal output activity. IEEE Trans. Nucle. Sci. 2004, 51 (4): 1434-1440. 10.1109/TNS.2004.832706.

    Article  Google Scholar 

  4. Schreiber T: Measuring Information Transfer. Phys. Rev. Lett. 2000, 85 (2): 461-464. 10.1103/PhysRevLett.85.461.

    Article  CAS  PubMed  Google Scholar 

  5. Perin R, Berger TK, Markram H: A synaptic organizing principle for cortical neuronal groups. Proc Natl Acad Sci USA. 2011, 108 (13): 5419-5424. 10.1073/pnas.1016051108.

    Article  PubMed Central  CAS  PubMed  Google Scholar 

  6. Shimono M, Beggs JM: Mesoscopic neuronal activity and neuronal network architecture. Neuroscience Research. 2011, 77: e304-10.1016/j.neures.2011.07.1326.

    Article  Google Scholar 

Download references


The authors are grateful to Olaf Sporns for important suggestions, to Rodrigo de Campos Perin in the Henry Markram team at EPFL for essential advices, and to Alan Litke, Fang-Chin Yeh, Shinya Ito, Pawel Hottowy and Deborah Gunning for their all supports to accomplish this study. This study was supported by a Grant-in-Aid for JSPS Fellows for Research Abroad.

Author information

Authors and Affiliations


Corresponding author

Correspondence to Masanori Shimono.

Rights and permissions

This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The Creative Commons Public Domain Dedication waiver ( applies to the data made available in this article, unless otherwise stated.

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Shimono, M., Beggs, J.M. Network community, clusters and hubs in cortical micro circuits. BMC Neurosci 15 (Suppl 1), F2 (2014).

Download citation

  • Published:

  • DOI: