RESUMO
Based on a nonlinear neuron model, the Poisson noise is used to imitate the noisy environments of neurons, and, further, the phenomenon of coherence resonance (CR) of a nonlinear neuron model subject to a voltage-gated channel noise and a random point trains synaptic noise is investigated. Based on the fractional noise theory and Euler schemes, the evolution of the membrane potential and the coefficient of variation (CV) of the interval-spike-interval of the neuron firing have been obtained. It is shown that, in the absence of external periodic signal, such CV can be decreased at a certain intensity of neurotransmitter arrivals trains lambda and a proper strength of the voltage-gated channel noise D, so that the coherence of the system is maximal and the phenomenon of CR can take place.
Assuntos
Humanos , Potenciais de Ação , Fisiologia , Córtex Cerebral , Biologia Celular , Fisiologia , Simulação por Computador , Modelos Neurológicos , Neurônios , Biologia Celular , Fisiologia , Distribuição de Poisson , Processos Estocásticos , Sinapses , FisiologiaRESUMO
The testicle tissue's pathological changes of Wistar rats in low frequency electromagnetic fields were observed and analyzed by Fourier transform infrared (FTIR) spectroscopy. The components of secondary structure were examined by use of derivative and curve-fitting techniques. The results showed some significant differences between the exposed group and the sham-exposed group on spectra. Especially, the analysis on the components of secondary structure of amide link I bond revealed a marked decrease in the ordered secondary structure of the exposed group. These findings indicate there will be damage to the testicle tissues that have been exposed to extremely low frequency electromagnetic fields for a long time.
Assuntos
Animais , Masculino , Ratos , Campos Eletromagnéticos , Estrutura Secundária de Proteína , Efeitos da Radiação , Distribuição Aleatória , Ratos Wistar , Espectroscopia de Infravermelho com Transformada de Fourier , Testículo , Química , Patologia , Efeitos da RadiaçãoRESUMO
Objective To investigate the phenomenon of coherence resonance(CR)in a nonlinear integrate-and-fire neuronal model(NIF)induced with correlated voltage-gated channel noise and synaptic noise.Meanwhile,the effects of intensity of the voltage-gated channel noise,intensity of the synaptic noise and the strength of the correlation between noises on coherence resonance are discussed.Methods Based on the adiabatic approximation theory and the two-state theory,the approximate expressions of the probability distribution of neuron first fire(FPD)and the coefficient of variation(CV)of the inter-spike intervals of neuron discharging were obtained.Results It was shown that the FPD and the CV were the function of intensities of the voltage-gated channel noise,intensities of the synaptic noise and the strength of the correlation between noises.Conclusion By choosing appropriate the intensity of noise and the strength of the correlation between noises,the minimum of the CV can be obtained,to make the maximum coherence of system and the phenomenon of coherence resonance will occur.