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Highly nonrandom features of synaptic connectivity in local cortical circuits

Song, S; Sjostrom, PJ; Reigl, M; Nelson, S; Chklovskii, DB; (2005) Highly nonrandom features of synaptic connectivity in local cortical circuits. PLOS BIOL , 3 (3) , Article e68. 10.1371/journal.pbio.0030068. Green open access

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Abstract

How different is local cortical circuitry from a random network? To answer this question, we probed synaptic connections with several hundred simultaneous quadruple whole-cell recordings from layer 5 pyramidal neurons in the rat visual cortex. Analysis of this dataset revealed several nonrandom features in synaptic connectivity. We confirmed previous reports that bidirectional connections are more common than expected in a random network. We found that several highly clustered three-neuron connectivity patterns are overrepresented, suggesting that connections tend to cluster together. We also analyzed synaptic connection strength as defined by the peak excitatory postsynaptic potential amplitude. We found that the distribution of synaptic connection strength differs significantly from the Poisson distribution and can be fitted by a lognormal distribution. Such a distribution has a heavier tail and implies that synaptic weight is concentrated among few synaptic connections. In addition, the strengths of synaptic connections sharing pre- or postsynaptic neurons are correlated, implying that strong connections are even more clustered than the weak ones. Therefore, the local cortical network structure can be viewed as a skeleton of stronger connections in a sea of weaker ones. Such a skeleton is likely to play an important role in network dynamics and should be investigated further.

Type: Article
Title: Highly nonrandom features of synaptic connectivity in local cortical circuits
Open access status: An open access version is available from UCL Discovery
DOI: 10.1371/journal.pbio.0030068
Publisher version: http://dx.doi.org/10.1371/journal.pbio.0030068
Language: English
Additional information: © 2005 Song et al. 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.
Keywords: DEVELOPING RAT NEOCORTEX, LONG-TERM POTENTIATION, 5 PYRAMIDAL NEURONS, VISUAL-CORTEX, ESCHERICHIA-COLI, COMPLEX NETWORKS, FIRING PATTERNS, BARREL CORTEX, ADULT-RAT, CELL
UCL classification: UCL
UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Life Sciences
URI: https://discovery.ucl.ac.uk/id/eprint/167506
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