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  • Oral presentation
  • Open Access

Dense gap-junction connections support dynamic Turing structures in the cortex

  • 1Email author,
  • 1,
  • 1 and
  • 2
BMC Neuroscience20078(Suppl 2):S2

Published: 6 July 2007


  • Diffusive Coupling
  • Inhibitory Neuron
  • Electrical Coupling
  • Cortical Model
  • Orientation Column

The recent report by Fukuda et al [1] provides convincing evidence for dense gap-junction connectivity between inhibitory neurons in the cat visual cortex, each neuron making 60 +/- 12 gap-junction dendritic connections with neurons in both the same and adjoining orientation columns. These resistive connections provide a source of diffusive current to the receiving neuron, supplementing the chemical-synaptic currents generated by incoming action-potential spike activity. Fukuda et al describe how the gap junctions form a dense and homogeneous electrical coupling of interneurons, and propose that this diffusion-coupled network provides the substrate for synchronization of neuronal populations.

To date, large-scale population-based mathematical models of the cortex have ignored diffusive communication between neurons. Here we augment a well-established mean-field cortical model [2] by incorporating gap-junction-mediated diffusion currents, and we investigate the implications of strong diffusive coupling. The significant result is the model prediction that the 2D cortex can spontaneously generate centimetre-scale Turing structures (spatial patterns), in which regions of high-firing activity are intermixed with regions of low-firing activity (see Fig. 1). Since coupling strength decreases with increases in firing rate, these patterns are expected to exchange contrast on a slow time-scale, with low-firing patches increasing their activity at the expense of high-firing patches. These theoretical predictions are consistent with the slowly fluctuating large-scale brain-activity images detected from the BOLD (blood oxygen-level-dependent) signal [3].
Figure 1
Figure 1

Diffusion-induced Turing patterns in a square cortex of side 25 cm. Panel a shows the case of zero diffusion: the cortex organizes into a diffuse, cloud-like pattern, but fails to generate a Turing structure. Panels b-d show increasing inhibitory diffusion. These cases evolve into stable serpentine Turing patterns containing alternating regions of low-(blue) and high-firing (red) cells.

Authors’ Affiliations

Department of Engineering, University of Waikato, Hamilton, New Zealand
Waikato Clinical School, University of Auckland, Hamilton, New Zealand


  1. Kosaka T, Singer W, Galuske RAW: Gap junctions among dendrites of cortical GABAergic neurons establish a dense and widespread intercolumnar network. J Neurosci. 2006, 26: 3434-3443. 10.1523/JNEUROSCI.4076-05.2006.PubMedView ArticleGoogle Scholar
  2. Steyn-Ross DA, Steyn-Ross ML, Sleigh JW, Wilson MT, Gillies IP, Wright JJ: The sleep cycle modelled as a cortical phase transition. J Biol Phys. 2005, 31: 547-569. 10.1007/s10867-005-1285-2.PubMedPubMed CentralView ArticleGoogle Scholar
  3. Fox MD, Snyder AZ, Vincent JL, Corbetta M, van Essen DC, Raichle ME: The human brain is intrinsically organized into dynamic, anticorrelated functional networks. Proc Nat Acad Sci USA. 102: 9673-9678. 10.1073/pnas.0504136102.Google Scholar


© Steyn-Ross et al; licensee BioMed Central Ltd. 2007

This article is published under license to BioMed Central Ltd.