Применение численного обращения преобразования Лапласа при исследовании нестационарных колебаний электромагнитоупругой толстостенной сферы
Numerical simulation of the oscillation thick walled shell electromagnetoelasticity
Mechanisms of cognitive control include monitoring and regulation of both task-specific attentional processes and non-specific motor threshold. Failures in one or the other of these two mechanisms may lead to different kinds of responses, post-response adaptations and, importantly, distinctive behavioral correlates. Slow responses can be interpreted as responses committed after attentional lapses and, therefore, during the state of uncertainty, while fast responses can be interpreted as responses committed in conditions of lowered motor threshold. Thus, slow and fast errors have different nature and require different brain adaptations.
The aim of the current study was to confirm the idea that modulations in oscillatory brain activity can distinguish between these two types of responses.
EEG was recorded during performance of the auditory two-choice condensation task, which requires sustained attention and does not require inhibition of prepotent responses.
Increased frontal midline theta (FMT) power was observed during pre-response time interval for both correct responses and errors. Enhanced error-related FMT power was found in post-response and post-feedback time intervals. Increased frontal beta power was observed in post-feedback time interval. We also observed significant positive trial-to-trial correlation between pre-response FMT power and response time (RT) for both correct responses and errors, negative trial-to-trial correlation between post-response FMT power and RT for errors, and positive trial-to-trial correlation between post-feedback frontal beta power and RT.
Thus, slow erroneous responses characterized by high uncertainty were accompanied by increased FMT power before the response and by increased frontal beta power following the feedback; these effects, presumably, reflect enhanced cognitive effort and feedback processing, respectively. On the contrary, fast erroneous responses characterized by low uncertainty led to increased post-response FMT power, which, presumably, reflects internal error detection. Thus, this study confirmed the idea that RT can be a valid index of uncertainty level, with high uncertainty occurring due to attentional lapses and low uncertainty occurring due to failures to keep a sufficiently high motor threshold.
The study was implemented in the framework of the Basic Research Program at the National Research University Higher School of Economics (HSE) in 2018.
Long-term oscillations of microwave emission generated in sunspot magnetospheres are detected with the Nobeyama Radioheliograph (NoRH) at a frequency of 17 GHz, and the Siberian Solar Radio Telescope (SSRT) at 5.7 GHz. Significant periodicities in the range of 22–170 min are found in the variation of the emission intensity, polarisation and the degree of circular polarisation. Periods of the oscillations are not stable: they are different in different sunspots and in the same sunspot on different days. A cross-correlation analysis shows the presence of common significant periods in both NoRH and SSRT data. The cross-correlation coefficients are typically lower than 0.5, which can be attributed to the different heights of the emission formation, and different mechanisms for the emission generation (gyroresonance and thermal bremstrahlung at 17 GHz, and pure gyroresonance at 5.7 GHz). The observational results are consistent with the global sunspot oscillation model.