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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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The configuration of the LCM.(A) The LCM simulates five cortical layers. Cortical layers are discretized to a grid of elements, which contain two neuron groups: excitatory and inhibitory. (B) The laminar connection between cortical layers is illustrated. Only the strong connections are shown in the figure. For the complete connection map please refer to Table S1 of Text S2. (C) The connections between neuron groups within a lamina are shown.
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pcbi-1002733-g001: The configuration of the LCM.(A) The LCM simulates five cortical layers. Cortical layers are discretized to a grid of elements, which contain two neuron groups: excitatory and inhibitory. (B) The laminar connection between cortical layers is illustrated. Only the strong connections are shown in the figure. For the complete connection map please refer to Table S1 of Text S2. (C) The connections between neuron groups within a lamina are shown.

Mentions: The LCM exploits the laminar architecture of the cortex. Five cortical layers (layer I to VI) are considered (cortical layers II and III are combined). Each layer is simulated using the continuum cortex model, and the layers are connected by laminar synaptic connections (see Figure 1). A synaptic connection map is created and used to control the connection between and within cortical layers (see Table S1 in Text S2). This connection map was based on empirical observations of the number of synapses formed between different types of neurons by Binzegger [22] (see Text S2). The connection map classifies the afferent synapses on each group of cortical neurons into three categories: 1) intracortical synapses, from within the visual cortex (), 2) cortico-cortical synapses, from other cortical areas (), and 3) thalamic synapses, projections from neurons in the lateral geniculate nucleus (LGN, ).


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

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

The configuration of the LCM.(A) The LCM simulates five cortical layers. Cortical layers are discretized to a grid of elements, which contain two neuron groups: excitatory and inhibitory. (B) The laminar connection between cortical layers is illustrated. Only the strong connections are shown in the figure. For the complete connection map please refer to Table S1 of Text S2. (C) The connections between neuron groups within a lamina are shown.
© Copyright Policy
Related In: Results  -  Collection

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

pcbi-1002733-g001: The configuration of the LCM.(A) The LCM simulates five cortical layers. Cortical layers are discretized to a grid of elements, which contain two neuron groups: excitatory and inhibitory. (B) The laminar connection between cortical layers is illustrated. Only the strong connections are shown in the figure. For the complete connection map please refer to Table S1 of Text S2. (C) The connections between neuron groups within a lamina are shown.
Mentions: The LCM exploits the laminar architecture of the cortex. Five cortical layers (layer I to VI) are considered (cortical layers II and III are combined). Each layer is simulated using the continuum cortex model, and the layers are connected by laminar synaptic connections (see Figure 1). A synaptic connection map is created and used to control the connection between and within cortical layers (see Table S1 in Text S2). This connection map was based on empirical observations of the number of synapses formed between different types of neurons by Binzegger [22] (see Text S2). The connection map classifies the afferent synapses on each group of cortical neurons into three categories: 1) intracortical synapses, from within the visual cortex (), 2) cortico-cortical synapses, from other cortical areas (), and 3) thalamic synapses, projections from neurons in the lateral geniculate nucleus (LGN, ).

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