eprintid: 167506 rev_number: 47 eprint_status: archive userid: 608 dir: disk0/00/16/75/06 datestamp: 2010-11-02 13:31:13 lastmod: 2021-09-19 23:02:43 status_changed: 2010-11-02 13:31:13 type: article metadata_visibility: show item_issues_count: 0 creators_name: Song, S creators_name: Sjostrom, PJ creators_name: Reigl, M creators_name: Nelson, S creators_name: Chklovskii, DB title: Highly nonrandom features of synaptic connectivity in local cortical circuits ispublished: pub divisions: UCL divisions: B02 divisions: C08 keywords: DEVELOPING RAT NEOCORTEX, LONG-TERM POTENTIATION, 5 PYRAMIDAL NEURONS, VISUAL-CORTEX, ESCHERICHIA-COLI, COMPLEX NETWORKS, FIRING PATTERNS, BARREL CORTEX, ADULT-RAT, CELL note: © 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. 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. date: 2005-03-01 publisher: PUBLIC LIBRARY SCIENCE official_url: http://dx.doi.org/10.1371/journal.pbio.0030068 vfaculties: VFLS oa_status: green language: eng primo: open primo_central: open_green article_type_text: Article verified: verified_batch elements_source: Web of Science elements_id: 86499 doi: 10.1371/journal.pbio.0030068 language_elements: EN lyricists_name: Sjostrom, Per lyricists_id: JSJOS72 full_text_status: public publication: PLOS BIOL volume: 3 number: 3 article_number: e68 issn: 1544-9173 citation: 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 <https://doi.org/10.1371/journal.pbio.0030068>. Green open access document_url: https://discovery.ucl.ac.uk/id/eprint/167506/1/167506.pdf