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Quantal Analysis Reveals a Functional Correlation between Presynaptic and Postsynaptic Efficacy in Excitatory Connections from Rat Neocortex

Lookup NU author(s): Professor Jenny ReadORCiD, Professor Andrew Trevelyan


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At many central synapses, the presynaptic bouton and postsynaptic density are structurally correlated. However, it is unknown whether this correlation extends to the functional properties of the synapses. To investigate this, we made recordings from synaptically coupled pairs of pyramidal neurons in rat visual cortex. The mean peak amplitude of EPSPs recorded from pairs of L2/3 neurons ranged between 40 mu V and 2.9 mV. EPSP rise times were consistent with the majority of the synapses being located on basal dendrites; this was confirmed by full anatomical reconstructions of a subset of connected pairs. Over a third of the connections could be described using a quantal model that assumed simple binomial statistics. Release probability (P-r) and quantal size (Q), as measured at the somatic recording site, showed considerable heterogeneity between connections. However, across the population of connections, values of P-r and Q for individual connections were positively correlated with one another. This correlation also held for inputs to layer 5 pyramidal neurons from both layer 2/3 and neighboring layer 5 pyramidal neurons, suggesting that during development of cortical connections presynaptic and postsynaptic strengths are dependently scaled. For 2/3 to 2/3 connections, mean EPSP amplitude was correlated with both Q and P-r values but uncorrelated with N, the number of functional release sites mediating the connection. The efficacy of a cortical connection is thus set by coordinated presynaptic and postsynaptic strength.

Publication metadata

Author(s): Hardingham NR, Read JCA, Trevelyan AJ, Nelson JC, Jack JJB, Bannister NJ

Publication type: Article

Publication status: Published

Journal: Journal of Neuroscience

Year: 2010

Volume: 30

Issue: 4

Pages: 1441-1451

Print publication date: 27/01/2010

ISSN (print): 0270-6474

ISSN (electronic): 1529-2401

Publisher: Society for Neuroscience


DOI: 10.1523/JNEUROSCI.3244-09.2010


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