fire properties
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- MeSH
- experimenty na zvířatech MeSH
- myofibrily MeSH
- potenciometrie MeSH
- žáby MeSH
- Publikační typ
- srovnávací studie MeSH
Following a pine beetle epidemic in British Columbia, Canada, we investigated the effect of fire severity on rhizosphere soil chemistry and ectomycorrhizal fungi (ECM) and associated denitrifying and nitrogen (N)-fixing bacteria in the root systems of regenerating lodgepole pine seedlings at two site types (wet and dry) and three fire severities (low, moderate, and high). The site type was found to have a much larger impact on all measurements than fire severity. Wet and dry sites differed significantly for almost all soil properties measured, with higher values identified from wet types, except for pH and percent sand that were greater on dry sites. Fire severity caused few changes in soil chemical status. Generally, bacterial communities differed little, whereas ECM morphotype analysis revealed ectomycorrhizal diversity was lower on dry sites, with a corresponding division in community structure between wet and dry sites. Molecular profiling of the fungal ITS region confirmed these results, with a clear difference in community structure seen between wet and dry sites. The ability of ECM fungi to colonize seedlings growing in both wet and dry soils may positively contribute to subsequent regeneration. We conclude that despite consecutive landscape disturbances (mountain pine beetle infestation followed by wildfire), the "signature" of moisture on chemistry and ECM community structure remained pronounced.
- MeSH
- Bacteria klasifikace genetika izolace a purifikace metabolismus MeSH
- borovice růst a vývoj mikrobiologie parazitologie MeSH
- brouci fyziologie MeSH
- dusík metabolismus MeSH
- ekosystém MeSH
- houby klasifikace genetika izolace a purifikace MeSH
- mykorhiza klasifikace genetika růst a vývoj izolace a purifikace MeSH
- nemoci rostlin parazitologie MeSH
- požáry MeSH
- půda chemie MeSH
- rhizosféra MeSH
- stromy růst a vývoj mikrobiologie parazitologie MeSH
- voda analýza MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- srovnávací studie MeSH
Statistical properties of spike trains as well as other neurophysiological data suggest a number of mathematical models of neurons. These models range from entirely descriptive ones to those deduced from the properties of the real neurons. One of them, the diffusion leaky integrate-and-fire neuronal model, which is based on the Ornstein-Uhlenbeck (OU) stochastic process that is restricted by an absorbing barrier, can describe a wide range of neuronal activity in terms of its parameters. These parameters are readily associated with known physiological mechanisms. The other model is descriptive, Gamma renewal process, and its parameters only reflect the observed experimental data or assumed theoretical properties. Both of these commonly used models are related here. We show under which conditions the Gamma model is an output from the diffusion OU model. In some cases, we can see that the Gamma distribution is unrealistic to be achieved for the employed parameters of the OU process.
- MeSH
- difuze * MeSH
- kybernetika MeSH
- modely neurologické * MeSH
- neurony * MeSH
- stochastické procesy MeSH
- Publikační typ
- časopisecké články MeSH
Parameters in diffusion neuronal models are divided into two groups; intrinsic and input parameters. Intrinsic parameters are related to the properties of the neuronal membrane and are assumed to be known throughout the paper. Input parameters characterize processes generated outside the neuron and methods for their estimation are reviewed here. Two examples of the diffusion neuronal model, which are based on the integrate-and-fire concept, are investigated--the Ornstein--Uhlenbeck model as the most common one and the Feller model as an illustration of state-dependent behavior in modeling the neuronal input. Two types of experimental data are assumed-intracellular describing the membrane trajectories and extracellular resulting in knowledge of the interspike intervals. The literature on estimation from the trajectories of the diffusion process is extensive and thus the stress in this review is set on the inference made from the interspike intervals.
- MeSH
- modely neurologické MeSH
- neurony MeSH
- Publikační typ
- práce podpořená grantem MeSH
- přehledy MeSH
The Ornstein-Uhlenbeck neuronal model is specified by two types of parameters. One type corresponds to the properties of the neuronal membrane, whereas the second type (local average rate of the membrane depolarization and its variability) corresponds to the input of the neuron. In this article, we estimate the parameters of the second type from an intracellular record during neuronal firing caused by stimulation (audio signal). We compare the obtained estimates with those from the spontaneous part of the record. As predicted from the model construction, the values of the input parameters are larger for the periods when neuron is stimulated than for the spontaneous ones. Finally, the firing regimen of the model is checked. It is confirmed that the neuron is in the suprathreshold regimen during the stimulation.
- MeSH
- akční potenciály fyziologie MeSH
- akustická stimulace metody MeSH
- časové faktory MeSH
- elektroencefalografie MeSH
- membránové potenciály fyziologie MeSH
- modely neurologické MeSH
- morčata MeSH
- nervové dráhy fyziologie MeSH
- neurony klasifikace fyziologie MeSH
- počítačové zpracování signálu MeSH
- reakční čas fyziologie MeSH
- stochastické procesy MeSH
- zvířata MeSH
- Check Tag
- morčata MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Due to known information processing capabilities of the brain, neurons are modeled at many different levels. Circuit theory is also often used to describe the function of neurons, especially in complex multi-compartment models, but when used for simple models, there is no subsequent biological justification of used parts. We propose a new single-compartment model of excitatory and inhibitory neuron, the capacitor-switch model of excitatory and inhibitory neuron, as an extension of the existing integrate-and-fire model, preserving the signal properties of more complex multi-compartment models. The correspondence to existing structures in the neuronal cell is then discussed for each part of the model. We demonstrate that a few such inter-connected model units are capable of acting as a chaotic oscillator dependent on fire patterns of the input signal providing a complex deterministic and specific response through the output signal. The well-known necessary conditions for constructing a chaotic oscillator are met for our presented model. The capacitor-switch model provides a biologically-plausible concept of chaotic oscillator based on neuronal cells.
- MeSH
- akční potenciály fyziologie MeSH
- modely neurologické MeSH
- mozek metabolismus MeSH
- neurony metabolismus MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
