ABSTRACT
Electromagnetic stimulation is an important neuromodulation technique that modulates the electrical activity of neurons and affects cortical excitability for the purpose of modulating the nervous system. The phenomenon of inverse stochastic resonance is a response mechanism of the biological nervous system to external signals and plays an important role in the signal processing of the nervous system. In this paper, a small-world neural network with electrical synaptic connections was constructed, and the inverse stochastic resonance of the small-world neural network under electromagnetic stimulation was investigated by analyzing the dynamics of the neural network. The results showed that: the Levy channel noise under electromagnetic stimulation could cause the occurrence of inverse stochastic resonance in small-world neural networks; the characteristic index and location parameter of the noise had significant effects on the intensity and duration of the inverse stochastic resonance in neural networks; the larger the probability of randomly adding edges and the number of nearest neighbor nodes in small-world networks, the more favorable the anti-stochastic resonance was; by adjusting the electromagnetic stimulation parameters, a dual regulation of the inverse stochastic resonance of the neural network can be achieved. The results of this study provide some theoretical support for exploring the regulation mechanism of electromagnetic nerve stimulation technology and the signal processing mechanism of nervous system.
Subject(s)
Action Potentials/physiology , Computer Simulation , Models, Neurological , Stochastic Processes , Neurons/physiology , Electromagnetic PhenomenaABSTRACT
Background noise may impose deleterious effects on cognitive processing. However, noise below the threshold level may increase the ability to detect stimuli via stochastic resonance mechanisms (SR). The present study investigates whether task performance is deteriorated or enhanced by 5-dB SNR and, if the task performance is enhanced, whether this facilitation in performance points to a particular neural area that serves to attenuate noise and/or increase effective task performance. The areas of interest are the cerebellum and hippocampus due to their roles in working memory (WM) and their links with attention. Fifteen healthy young Malay adults performed three tasks during fMRI scanning: listening to babble noise (N), WM task in quiet (WMQ), and WM task in noise (WMN). Activated regions during N are bilateral STG and MTG. Both WM tasks produced similar activation in a network of areas in the frontal, temporal and parietal lobes. However, the two tasks demonstrated marked differences in the left hippocampus, right posterior cerebellum, and bilateral anterior cerebellum. Moreover, the results obtained from the behavioral task demonstrated that participants responded better in the presence of noise. These results support the hypothesis that the left hippocampus, right posterior cerebellum, and bilateral anterior cerebellum may be involved in attenuating noise and/or increasing attention to task performance, which could be due to SR mechanisms operating in the presence of noise. These results collectively suggest leftward asymmetries during the tasks with the right posterior cerebellum, bilateral anterior cerebellum, and left hippocampus providing compensatory attention processes, at least in the context of this study.
Subject(s)
Cognition , Hippocampus , Memory, Short-Term , Noise Effects , Magnetic Resonance Imaging/methods , Stochastic ProcessesABSTRACT
The effect of colored noise on circadian oscillation and internal signal stochastic resonance(ISSR) has been studied in a Neurospora circadian clock system. The result shows that the correlation time of colored noise can affect strongly the strength of ISSR. For the case of no external signal(ES), the correlation time of colored noise plays a suppressive role for ISSR, and the suppressive role is increased with the increment of correlation time of colored noise. When the ES is injected to the system, with the increasing of the correlation time of colored noise, not only its suppressive role for ISSR is increased, but also the single peak ISSR can be transformed as internal single stochastic bi-resonance (ISSBR). There exists an optimal frequency of ES for the ISSR information amplification, while the ISSR is suppressed for another frequency of ES. In contrast to external colored noise, internal colored noise is more efficient to sustain and amplify the ISSR information. Furthermore, there exists a critical noise intensity for destroying the difference between white and colored noises.
ABSTRACT
Objective To investigate the change of threshold of electrical sense through experiments in the presence of electrical noise according to stochastic resonance phenomenon that has been observed in somatosensory system.Method Psychophysical experiments were carried out using both single stimulus method based on random-gradient method and one-interval-forced-choice method.The glabrous skin of human fingers was choosed as the experimental objects,which was stimulated by square wave electrical signal mixed with electrical noise.Result The corresponding threshold of electrical sense can be reduced by the effect of external electrical noises.Conclusion Although electrical sense is not natural sense,stochastic resonance can occur in it, and effect of noise on enhancing this sense can be implemented by controlling external noises.
ABSTRACT
Aim To apply stochastic resonance algorithm (SRA) to quantitative analysis of weak chromatographic signal, which was embedded in the noise. Methods Based on the theory of stochastic resonance (SR), a simple and effective SRA has been established to improve analytical detection limits of chromatographic analysis, which apply to enhance the signal to noise ratio by the optimization of the parameters and Runge-Kutta method, was established. The method was used to quantitative analysis of phenazopyridine in human plasma by HPLC/UV. Meanwhile this method is compared with HPLC/MS.Results By experimental chromatographic data sets, an excellent quantitative relationship between concentrations of phenazopyridine and their responses had been obtained. The concentration of phenazopyridine in plasma determined by HPLC/UV with SRA and HPLC/MS showed that there was no significant difference (P ＞ 0.05) between the two methods. Conclusion The new method was feasible.
ABSTRACT
Objective To study whether mechanical noise acting on the sacculus could enhance the SNR of the 8th nerve’s response.Methods Driving PZT by adding white noise of various level to periodic signals(f=100 Hz),the directly mechanical stimuli was give to the five sacculus submerged in a solution containing perilymph-like, and the afferent activity the 8th nerve was recorded.Results The SNR of the nerve signal was improved by addition nanometer-level noise to the periodic stimuli in all responsive animal(4.1 dB, on average).It was found that 2.3 nm of mechanical noise enhanced the response of the saccular nerve.Conclusion The addition of a few nanometers of noise to a periodic stimuli leads to a substantial improvement in the SNR of the nerve’s response.