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

Du J, Vegh V, Reutens DC - PLoS Comput. Biol. (2012)

Bottom Line: The power spectra of LFPs were calculated and compared with existing empirical data.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.

View Article: PubMed Central - PubMed

Affiliation: The University of Queensland, Centre for Advanced Imaging, Brisbane, Queensland, Australia.

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.

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Related in: MedlinePlus

Afferent spike rates corresponding to visual stimulations.(A) Spike rates correspond to spontaneous activity followed by constant visual stimulation, and (B) spike rates represent to spontaneous activity prior to intermittent light stimulation.
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pcbi-1002733-g002: Afferent spike rates corresponding to visual stimulations.(A) Spike rates correspond to spontaneous activity followed by constant visual stimulation, and (B) spike rates represent to spontaneous activity prior to intermittent light stimulation.

Mentions: We simulated the effect of visual stimulation on LFPs using the LCM. Different forms of visual stimulation were assumed to form different spike trains projecting from the LGN to deeper cortical layers of the visual cortex (Layer IV, V and VI, see Table S1 in Text S2). Three states of visual stimulation were examined in the model: 1) spontaneous activity without visual stimulation, 2) constant visual stimulation, and 3) intermittent light stimulation. As illustrated in Figure 2, these conditions correspond to afferent spike trains with the shape of small amplitude white noise, large amplitude white noise (the random number generator from [23] was adopted), and recurring Gaussian peaks, respectively.


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

Du J, Vegh V, Reutens DC - PLoS Comput. Biol. (2012)

Afferent spike rates corresponding to visual stimulations.(A) Spike rates correspond to spontaneous activity followed by constant visual stimulation, and (B) spike rates represent to spontaneous activity prior to intermittent light stimulation.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3475685&req=5

pcbi-1002733-g002: Afferent spike rates corresponding to visual stimulations.(A) Spike rates correspond to spontaneous activity followed by constant visual stimulation, and (B) spike rates represent to spontaneous activity prior to intermittent light stimulation.
Mentions: We simulated the effect of visual stimulation on LFPs using the LCM. Different forms of visual stimulation were assumed to form different spike trains projecting from the LGN to deeper cortical layers of the visual cortex (Layer IV, V and VI, see Table S1 in Text S2). Three states of visual stimulation were examined in the model: 1) spontaneous activity without visual stimulation, 2) constant visual stimulation, and 3) intermittent light stimulation. As illustrated in Figure 2, these conditions correspond to afferent spike trains with the shape of small amplitude white noise, large amplitude white noise (the random number generator from [23] was adopted), and recurring Gaussian peaks, respectively.

Bottom Line: The power spectra of LFPs were calculated and compared with existing empirical data.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.

View Article: PubMed Central - PubMed

Affiliation: The University of Queensland, Centre for Advanced Imaging, Brisbane, Queensland, Australia.

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.

Show MeSH
Related in: MedlinePlus