Abstract Background When forecasting the future, people often underestimate the likelihood of adverse life events, a phenomenon known as optimism bias. While transcranial alternating current stimulation (tACS) over frontal regions has been employed to modulate various cognitive and emotional functions, its potential impact on optimism bias remains unexplored. Results Using a single-blind, sham-controlled, between-subjects design, we investigated the effects of alpha- and gamma-tACS on optimism bias. Three groups of participants received 15-min of either individualized alpha frequency (IAF)-tACS, 40 Hz-tACS, or sham stimulation over the right frontal cortex during rest. To assess how tACS impacted the optimism bias, participants completed a belief update task before and immediately after the tACS. To assess potential delayed effect of the tACS, participants completed a delay estimation task 24 hours later. We found that across all three groups, participants showed the classic optimism bias, such that they were more likely to update their beliefs toward desirable than undesirable feedback. Notably, compared to the sham and IAF-tACS groups, 40 Hz-tACS further enhanced optimism biases after 24 hours. Conclusion These findings suggest that right frontal gamma- but not alpha-tACS could effectively modulate the long-term optimistic belief updating. Our study highlights the potential of non-invasive brain stimulation as a promising tool for altering optimism biases, which may benefit individuals with pessimistic outlooks.
Recent advances have demonstrated that magnetic stimulation provides an effective and noninvasive way to enhance neurological functioning across multiple cognitive and motor domains. The present study extends this work by investigating the potential of magnetic fields to enhance human vigilance, measured via heart rate variability (HRV). In a sham-controlled study, HRV signal was analyzed across both the time and frequency domains for 15 participants as they were exposed to magnetic stimulation. Our findings demonstrate that magnetic stimulation is capable of fortifying vigilance, as indexed by several key HRV components: increased RR variability, decreased rootmean-square of successive difference-value (RMSSD), reduced low frequency (LF) signal power, and increased high frequency (HF) signal power. Given the indication that magnetic stimuli are indeed capable of improving these key correlates of vigilance, we discuss several important implications.
Abstract Variability in visual perception in response to consistent stimuli is a fundamental phenomenon linked to fluctuations in prestimulus low-frequency neural oscillations—particularly in the alpha (8–13 Hz) and beta (13–30 Hz) bands—typically measured by their power in electroencephalography (EEG) signals. However, the causal role of these prestimulus alpha and beta power fluctuations in visual perception remains unestablished. In this study, we investigated whether prestimulus alpha and beta power causally affect visual perception using transcranial random noise stimulation (tRNS). In a sham-controlled, single-blind, within-subject design, 29 participants performed a visual detection task while receiving occipital tRNS. Online functional near-infrared spectroscopy (fNIRS) was used to measure cortical excitability during stimulation, and offline EEG signals were collected after stimulation. Mental fatigue was incorporated as a state-dependent factor influencing tRNS effects. Our findings demonstrate that, primarily under low fatigue states, tRNS increased cortical excitability during stimulation (indicated by increased fNIRS oxyhemoglobin amplitude), decreased subsequent prestimulus EEG alpha and beta power, and consequently reduced the visual contrast threshold (VCT), indicating enhanced visual perception. Sensitivity analysis revealed that alpha oscillations contributed more significantly to visual perception than beta oscillations under low fatigue. Additionally, the state-dependent effects of tRNS may result from different sensitivities of VCT to neural oscillations across fatigue states. These results provide causal evidence linking prestimulus alpha and beta power to visual perception and underscore the importance of considering brain states in neuromodulation research. Our study advances the understanding of the neural mechanisms underlying visual perception and suggests potential therapeutic applications targeting neural oscillations. Significance statement Understanding why we perceive identical visual stimuli differently is a fundamental question in neuroscience. This study provides causal evidence that prestimulus alpha and beta neural oscillations directly influence visual perception, particularly under low mental fatigue state. By using tRNS alongside fNIRS and EEG recordings, we demonstrate that modulating neural excitability can alter perceptual outcomes. Our findings highlight the importance of considering brain state—such as fatigue levels—in neuromodulation research. This work advances our understanding of the neural mechanisms underlying visual perception and opens avenues for developing targeted interventions to enhance sensory processing and cognitive functions, potentially benefiting individuals with perceptual or attentional disorders.
Railways are important parts of our transportation,it's also modernization programmes invested by our country.For the current problems of cost control in railway project,relevant departments should pay more attention to cost management of railway project and minimize the waste of funds.This paper focuses on the cost control in railway construction.
Vigilant attention plays an important role in some industries and everyday life. However, its mechanism relating to phase synchronization of cortical oscillations is still unknown, which hinders the development of predicting and preventing vigilant attentional deficit. This study utilized psychomotor vigilance test (PVT) to elicit vigilance decrement. High and low levels of vigilant attention were represented by short and long reaction time, respectively. Electroencephalogram (EEG) was collected and phase synchronization between prefrontal and parietal cortices was analyzed by using debiased weighted phase lag index (dWPLI). The result suggests that vigilant attention of high level has earlier timing of theta (4-8Hz) phase synchronization, compared with that of low level. We concluded that phase synchronization may relate closely with the variation of vigilant attention.
The intricate relationship between prestimulus alpha oscillations and visual contrast detection variability has been the focus of numerous studies. However, the causal impact of prestimulus alpha traveling waves on visual contrast detection remains largely unexplored. In our research, we sought to discern the causal link between prestimulus alpha traveling waves and visual contrast detection across different levels of mental fatigue. Using electroencephalography alongside a visual detection task with 30 healthy adults (13 females; 17 males), we identified a robust negative correlation between prestimulus alpha forward traveling waves (FTWs) and visual contrast threshold (VCT). Inspired by this correlation, we utilized 45/-45° phase-shifted transcranial alternating current stimulation (tACS) in a sham-controlled, double-blind, within-subject experiment with 33 healthy adults (23 females; 10 males) to directly modulate these alpha traveling waves. After the application of 45° phase-shifted tACS, we observed a substantial decrease in FTW and an increase in backward traveling waves, along with a concurrent increase in VCT, compared with the sham condition. These changes were particularly pronounced under a low fatigue state. The findings of state-dependent tACS effects reveal the potential causal role of prestimulus alpha traveling waves in visual contrast detection. Moreover, our study highlights the potential of 45/-45° phase-shifted tACS in cognitive modulation and therapeutic applications.
Background: Emotion recognition is among the hot topics in the field of psychology and engineering. As a type of emotion, tension plays an important role in daily life. As such, tension intensity recognition (TIR) is of greatly value. Method: This study employed selected clips of a horror movie to elicit tension of different intensity levels, during which four types of bio-signals were collected from 4 participants. These signals included electroencephalogram (EEG), electrocardiogram (ECG), respiration (RSP) and electrodermal activity (EDA) signals. After that, a support vector machine (SVM) based classification was performed to differentiate fear tension levels, employing features extracted from multi-physiological signals. Results: EEG analysis showed that the power spectrum of EEG signals present monotonic changes with the increase of intensity at specific brain regions. The recognition accuracy using features from multiple physiology signals reached 83.33%. Conclusion: To our knowledge, this is among the first studies to evaluate emotion intensity levels using multiple electro-physiological signals. Our study demonstrated the feasibility and effectiveness of using these physiological features for the assessment of tension levels, providing further insights in the field of quantitative emotion studies.
It is commonly believed that brain has faster reaction speed and higher reaction accuracy on visual-auditory bimodal stimuli than single modal stimuli in current neuropsychological researches, while visual-auditory bimodal stimuli (VABS) do not show corresponding superiority in BCI system. This paper aims at investigating whether semantically congruent stimuli could also get better performance than semantically incongruent stimuli in Brain Computer Interface (BCI) system. Two VABS based paradigms (semantically congruent or incongruent) were conducted in this study. 10 healthy subjects participated in the experiment in order to compare the two paradigms. The results indicated that the higher Event-related potential (ERP) amplitude of semantic incongruent paradigm were observed both in target and non-target stimuli. Nevertheless, we didn't observe significant difference of classification accuracy between congruent and incongruent conditions. Most participants showed their preference on semantically congruent condition for less workload needed. This finding demonstrated that semantic congruency has positive effect on behavioral results (less workload) and insignificant effect on system efficiency.
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