Geometric and functional organization of cortical circuits

Gordon M G Shepherd, Armen Stepanyants, Ingrid Bureau, Dmitri Chklovskii, Karel Svoboda*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

163 Scopus citations

Abstract

Can neuronal morphology predict functional synaptic circuits? In the rat barrel cortex, 'barrels' and 'septa' delineate an orderly matrix of cortical columns. Using quantitative laser scanning photostimulation we measured the strength of excitatory projections from layer 4 (L4) and L5A to L2/3 pyramidal cells in barrel- and septum-related columns. From morphological reconstructions of excitatory neurons we computed the geometric circuit predicted by axodendritic overlap. Within most individual projections, functional inputs were predicted by geometry and a single scale factor, the synaptic strength per potential synapse. This factor, however, varied between projections and, in one case, even within a projection, up to 20-fold. Relationships between geometric overlap and synaptic strength thus depend on the laminar and columnar locations of both the pre- and postsynaptic neurons, even for neurons of the same type. A large plasticity potential appears to be incorporated into these circuits, allowing for functional 'tuning' with fixed axonal and dendritic arbor geometry.

Original languageEnglish (US)
Pages (from-to)782-790
Number of pages9
JournalNature neuroscience
Volume8
Issue number6
DOIs
StatePublished - Jun 2005

ASJC Scopus subject areas

  • Neuroscience(all)

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