title: Highly nonrandom features of synaptic connectivity in local cortical circuits.
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.
authors.affiliation: Cold Spring Harbor Laboratory, Cold Spring Harbor, New York, USA.
authors.forename: Sen
authors.initials: S
authors.lastname: Song
authors.forename: Per Jesper
authors.initials: PJ
authors.lastname: Sjöström
authors.forename: Markus
authors.initials: M
authors.lastname: Reigl
authors.forename: Sacha
authors.initials: S
authors.lastname: Nelson
authors.forename: Dmitri B
authors.initials: DB
authors.lastname: Chklovskii
mesh_terms: D000818:Animals; D002450:Cell Communication / Q000502:physiology; D066298:In Vitro Techniques; D009434:Neural Pathways / Q000502:physiology; D009473:Neuronal Plasticity; D009474:Neurons / Q000502:physiology*; D051381:Rats; D015398:Signal Transduction; D013569:Synapses / Q000502:physiology*; D014793:Visual Cortex / Q000502:physiology*
references.citation: Nature. 1996 Aug 29;382(6594):807-10
references.pmid: 8752273
references.citation: J Physiol. 2003 Aug 15;551(Pt 1):139-53
references.pmid: 12813147
references.citation: Neuron. 2001 Dec 6;32(5):883-98
references.pmid: 11738033
references.citation: Phys Rev Lett. 2003 Oct 17;91(16):168701
references.pmid: 14611445
references.citation: J Comp Neurol. 1985 Aug 15;238(3):263-74
references.pmid: 4044915
references.citation: Science. 2002 Oct 25;298(5594):824-7
references.pmid: 12399590
references.citation: Science. 2003 Dec 12;302(5652):1981-4
references.pmid: 14671309
references.citation: Int Rev Physiol. 1978;17:149-91
references.pmid: 359497
references.citation: Science. 1999 Oct 15;286(5439):509-12
references.pmid: 10521342
references.citation: J Comp Neurol. 1994 Jan 22;339(4):475-94
references.pmid: 8144742
references.citation: Nat Rev Genet. 2004 Feb;5(2):101-13
references.pmid: 14735121
references.citation: Science. 2002 Aug 30;297(5586):1551-5
references.pmid: 12202830
references.citation: Cereb Cortex. 2002 Sep;12(9):936-53
references.pmid: 12183393
references.citation: Nat Neurosci. 1998 Sep;1(5):395-403
references.pmid: 10196530
references.citation: J Physiol. 1999 Nov 15;521 Pt 1:169-90
references.pmid: 10562343
references.citation: BMC Biol. 2004;2:25
references.pmid: 15574204
references.citation: Biol Cybern. 2002 Dec;87(5-6):446-58
references.pmid: 12461634
references.citation: PLoS Biol. 2004 Nov;2(11):e329
references.pmid: 15514700
references.citation: Science. 2002 May 3;296(5569):910-3
references.pmid: 11988575
references.citation: IEEE Trans Biomed Eng. 1989 Jan;36(1):4-14
references.pmid: 2646211
references.citation: Philos Trans R Soc Lond B Biol Sci. 1986 Nov 12;314(1165):1-340
references.pmid: 22462104
references.citation: Nat Neurosci. 1999 Dec;2(12):1098-105
references.pmid: 10570487
references.citation: J Neurophysiol. 1993 Dec;70(6):2354-69
references.pmid: 8120587
references.citation: J Neurosci. 2004 Mar 24;24(12):2989-3001
references.pmid: 15044538
references.citation: Neuron. 2004 Sep 2;43(5):745-57
references.pmid: 15339654
references.citation: Nature. 2003 May 15;423(6937):283-8
references.pmid: 12748641
references.citation: Cereb Cortex. 1997 Sep;7(6):523-33
references.pmid: 9276177
references.citation: Nature. 1995 Nov 16;378(6554):281-4
references.pmid: 7477347
references.citation: J Neurophysiol. 2004 Jul;92(1):600-8
references.pmid: 15056678
references.citation: Neuron. 2003 Feb 6;37(3):499-511
references.pmid: 12575956
references.citation: Neuron. 2003 Aug 14;39(4):641-54
references.pmid: 12925278
references.citation: Proc Natl Acad Sci U S A. 2000 Mar 28;97(7):3619-24
references.pmid: 10737806
references.citation: J Neurosci. 1996 May 15;16(10):3209-18
references.pmid: 8627359
references.citation: J Neurosci. 1993 May;13(5):2199-216
references.pmid: 8386756
references.citation: J Neurophysiol. 1995 Mar;73(3):1145-56
references.pmid: 7608761
references.citation: J Bacteriol. 2002 Jan;184(1):152-64
references.pmid: 11741855
references.citation: Science. 1997 Jan 10;275(5297):213-5
references.pmid: 8985014
references.citation: Cereb Cortex. 2003 Jan;13(1):5-14
references.pmid: 12466210
references.citation: Neuron. 2001 Dec 20;32(6):1149-64
references.pmid: 11754844
references.citation: Nature. 1996 Oct 31;383(6603):815-9
references.pmid: 8893005
references.citation: Nat Neurosci. 2000 Jul;3(7):701-7
references.pmid: 10862703
references.citation: J Physiol. 1962 Jan;160:106-54
references.pmid: 14449617
references.citation: Nature. 2001 Mar 8;410(6825):268-76
references.pmid: 11258382
references.citation: Science. 2004 Apr 23;304(5670):559-64
references.pmid: 15105494
references.citation: J Physiol. 1991;440:735-69
references.pmid: 1666655
references.citation: Neural Netw. 2001 Jul-Sep;14(6-7):815-24
references.pmid: 11665773
references.citation: J Neurosci. 2002 Nov 15;22(22):9885-94
references.pmid: 12427845
references.citation: Neuron. 2001 Mar;29(3):691-701
references.pmid: 11301028
references.citation: Phys Rev Lett. 2002 Mar 11;88(10):108701
references.pmid: 11909388
references.citation: J Neurophysiol. 1988 Sep;60(3):909-24
references.pmid: 3171666
references.citation: Science. 2001 Aug 3;293(5531):868-72
references.pmid: 11486089
references.citation: Neuron. 2001 Oct 25;32(2):339-50
references.pmid: 11684002
references.citation: Nature. 1998 Jun 4;393(6684):440-2
references.pmid: 9623998
references.citation: Science. 2004 Mar 5;303(5663):1538-42
references.pmid: 15001784
references.citation: Biol Cybern. 2003 Mar;88(3):210-8
references.pmid: 12647228
references.citation: Proc Natl Acad Sci U S A. 1998 Jun 9;95(12):7121-6
references.pmid: 9618549
references.citation: J Physiol. 1997 Apr 15;500 ( Pt 2):409-40
references.pmid: 9147328
references.citation: Nature. 2004 Feb 26;427(6977):839-43
references.pmid: 14985762
references.citation: Neuron. 1992 Dec;9(6):1089-97
references.pmid: 1334418
references.citation: J Neurosci. 1998 Dec 15;18(24):10464-72
references.pmid: 9852584
references.citation: Acta Morphol Hung. 1990;38(3-4):159-67
references.pmid: 2102598
references.citation: J Neurosci. 1999 May 15;19(10):3827-35
references.pmid: 10234015
references.citation: J Neurosci. 2002 Nov 15;22(22):9668-78
references.pmid: 12427822