The Impact of Structural Heterogeneity on Excitation-Inhibition Balance in Cortical Networks

Itamar D. Landau, Robert Egger, Vincent J. Dercksen, Marcel Oberlaender, Haim Sompolinsky*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

82 Scopus citations

Abstract

Models of cortical dynamics often assume a homogeneous connectivity structure. However, we show that heterogeneous input connectivity can prevent the dynamic balance between excitation and inhibition, a hallmark of cortical dynamics, and yield unrealistically sparse and temporally regular firing. Anatomically based estimates of the connectivity of layer 4 (L4) rat barrel cortex and numerical simulations of this circuit indicate that the local network possesses substantial heterogeneity in input connectivity, sufficient to disrupt excitation-inhibition balance. We show that homeostatic plasticity in inhibitory synapses can align the functional connectivity to compensate for structural heterogeneity. Alternatively, spike-frequency adaptation can give rise to a novel state in which local firing rates adjust dynamically so that adaptation currents and synaptic inputs are balanced. This theory is supported by simulations of L4 barrel cortex during spontaneous and stimulus-evoked conditions. Our study shows how synaptic and cellular mechanisms yield fluctuation-driven dynamics despite structural heterogeneity in cortical circuits.

Original languageEnglish
Pages (from-to)1106-1121
Number of pages16
JournalNeuron
Volume92
Issue number5
DOIs
StatePublished - 7 Dec 2016

Bibliographical note

Publisher Copyright:
© 2016 The Author(s)

Keywords

  • adaptation
  • balance
  • cortical networks
  • dynamics
  • homeostatic plasticity
  • inhibition

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