The laminar cortex model: a new continuum cortex model incorporating laminar architecture

Du, Jiaxin, Vegh, Viktor and Reutens, David C. (2012) The laminar cortex model: a new continuum cortex model incorporating laminar architecture. PLoS Computational Biology, 8 10: e1002733.1-e1002733.9. doi:10.1371/journal.pcbi.1002733


Author Du, Jiaxin
Vegh, Viktor
Reutens, David C.
Title The laminar cortex model: a new continuum cortex model incorporating laminar architecture
Journal name PLoS Computational Biology   Check publisher's open access policy
ISSN 1553-734X
1553-7358
Publication date 2012-10-01
Year available 2012
Sub-type Article (original research)
DOI 10.1371/journal.pcbi.1002733
Open Access Status DOI
Volume 8
Issue 10
Start page e1002733.1
End page e1002733.9
Total pages 9
Place of publication San Francisco, CA, United States
Publisher Public Library of Science
Language eng
Subject 1105 Ecology, Evolution, Behavior and Systematics
2611 Modelling and Simulation
2303 Ecology
1312 Molecular Biology
1311 Genetics
2804 Cellular and Molecular Neuroscience
1703 Computational Theory and Mathematics
Abstract Blood oxygenation level dependent (BOLD) functional MRI has been used for inferring layer specific activation in humans. However, intracortical veins perpendicular to the cortical surface are suspected to degrade the laminar specificity as they drain blood from the microvasculature and BOLD signal is carried over from lower to upper cortical layers on its way to the pial surface. In this work, a vascular model of the cortex is developed to investigate the laminar specificity of the BOLD signal for Spin Echo (SE) and Gradient Echo (GE) following the integrative model presented by Uludağ et al. (2009). The results of the simulation show that the laminar point spread function (PSF) of the BOLD signal presents similar features across all layers. The PSF for SE is highly localised whereas for GE there is a flat tail running to the pial surface, with amplitude less than a quarter of the response from the layer itself. Consequently the GE response at any layer will also contain a contribution accumulated from all lower layers.
Formatted abstract
Local field potentials (LFPs) are widely used to study the function of local networks in the brain. They are also closely correlated with the blood-oxygen-level-dependent signal, the predominant contrast mechanism in functional magnetic resonance imaging. We developed a new laminar cortex model (LCM) to simulate the amplitude and frequency of LFPs. Our model combines the laminar architecture of the cerebral cortex and multiple continuum models to simulate the collective activity of cortical neurons. The five cortical layers (layer I, II/III, IV, V, and VI) are simulated as separate continuum models between which there are synaptic connections. The LCM was used to simulate the dynamics of the visual cortex under different conditions of visual stimulation. LFPs are reported for two kinds of visual stimulation: general visual stimulation and intermittent light stimulation. The power spectra of LFPs were calculated and compared with existing empirical data. The LCM was able to produce spontaneous LFPs exhibiting frequency-inverse (1/ƒ) power spectrum behaviour. Laminar profiles of current source density showed similarities to experimental data. General stimulation enhanced the oscillation of LFPs corresponding to gamma frequencies. During simulated intermittent light stimulation, the LCM captured the fundamental as well as high order harmonics as previously reported. The power spectrum expected with a reduction in layer IV neurons, often observed with focal cortical dysplasias associated with epilepsy was also simulated.
Keyword Gradient echo
Layer specific BOLD fMRI
Spatial specificity
Spin echo
Vascular cortical model
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Official 2013 Collection
Centre for Advanced Imaging Publications
 
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Created: Wed, 31 Oct 2012, 02:18:29 EST by Sandrine Ducrot on behalf of Centre for Advanced Imaging