Network community, clusters and hubs in cortical micro circuits
© Shimono and Beggs; licensee BioMed Central Ltd. 2014
Published: 21 July 2014
Networks of cortical neurons are essentially non-random . Although it is known that such networks show interesting structure at multiple temporal and spatial scales , 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 . Second, we reconstructed effective connectivity using transfer entropy . 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).
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.
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