Internal stochastic resonance in two coupled liquid membrane oscillators

Enhanced corticomuscular coherence by external stochastic noise

Noise can have beneficial effects as shown by the stochastic resonance (SR) phenomenon which is characterized by performance improvement when an optimal noise is added. Modern attempts to improve human performance utilize this phenomenon. The purpose of the present study was to investigate whether performance improvement by addition of optimum noise (ON) is related to increased cortical motor spectral power (SP) and increased corticomuscular coherence. Eight subjects performed a visuomotor task requiring to compensate with the right index finger a static force (SF) generated by a manipulandum on which Gaussian noise was applied. The finger position was displayed on-line on a monitor as a small white dot which the subjects had to maintain in the center of a green bigger circle. Electroencephalogram from the contralateral motor area, electromyogram from active muscles and finger position were recorded. The performance was measured by the mean absolute deviation (MAD) of the white dot from the zero position. ON compared to the zero noise condition induced an improvement in motor accuracy together with an enhancement of cortical motor SP and corticomuscular coherence in beta-range. These data suggest that the improved sensorimotor performance via SR is consistent with an increase in the cortical motor SP and in the corticomuscular coherence.

Enhancement and sustainment of internal stochastic resonance in unidirectional coupled neural system

In this study, the collective dynamical behavior of two unidirectionally, linearly coupled neurons was investigated. Our investigation illustrates that, depending on the coupling strength, the internal stochastic resonance (ISR) effect observed in one of the two neurons could be amplified or sustained by the other. The amplification of ISR is enhanced as the coupling strength is increased from 0. However, when the coupling strength is increased above a certain level, the amplification of ISR is reduced, implicating that there exists an optimal coupling strength for the information flow between two neurons. As the coupling strength is increased further, i.e., above the critical level, synchronization of the two subsystems is achieved, yet the two subsystems exhibit the same magnitude response to the external noise, suggesting that the information transmission among coupled subunits could not be improved by further enhancing their coupling strength. And similar phenomena could also be obtained for the nonidentical case.

Controlling of explicit internal signal stochastic resonance by external signal

Explicit internal signal stochastic resonance (EISSR) is investigated in a model of energy transduction of molecular machinery when noise is added to the region of oscillation in the presence of external signal (ES). It is found that EISSR could be controlled, i.e., enhanced or suppressed by adjusting frequency (omega(e)) and amplitude (A) of ES, and that there exits an optimal frequency for ES, which makes EISSR strength reach the maximum. Meanwhile, a critical amplitude (A(c)) is found, which is a threshold of occurrence of EISSR. Finally, the difference and similarity between EISSR and IISSR (implicit internal signal stochastic resonance) are discussed.