Di Wu

SignificanceTraditional exposure therapy or cognitive training requires repeated presentation of unwanted stimuli, whereas localizationist neuromodulation overlooks individual variation. We propose a closed-loop neuromodulation approach termed functional near-infrared spectroscopy-decoded neurofeedback training, designed to modify prefrontal hemoglobin dynamics and neural activity patterns.AimWe aim to enhance interference control without interfering stimuli using a data-driven, individualized, time-resolved decoded neurofeedback, potentially offering a balanced compromise and an alternative to traditional approaches.ApproachWe employed a randomized, double-blind, between-group design. Both the decoded neurofeedback group (DecNef, n=20) and the Sham group (Sham, n=25) developed individualized decoders with a 1-s temporal resolution following the color-word Stroop task (CWST) before training. Both groups received decoded neurofeedback training sessions lasting 25 min daily for three consecutive days, but there was a gap in their decoding accuracy due to differences in sample size. Interference control was assessed via CWST at three timepoints: pre-training (pre-test), post-training (post-test), and 1-week follow-up.ResultsThere was no significant difference in feedback scores between groups, but the Stroop effect of reaction time (RT) in the DecNef group showed a significant reduction compared with the Sham group, both at post-test (t=3.056, p=0.004) and follow-up test (t=2.180, p=0.035). The difference wave amplitude (incongruent minus congruent trials) for hemodynamic response functions significantly decreased at post-test in the DecNef group (within a continuous period of 7 to 12 s, p<0.05), but not in the Sham group. Multivariate pattern analysis (MVPA) revealed significantly higher classification accuracy in the DecNef group compared with the Sham group (t=2.370, p=0.024); furthermore, this classification accuracy showed a significant negative correlation with changes in the RT Stroop effect (r=−0.36, p=0.015).ConclusionsWe proposed a closed-loop neuromodulation approach designed to modify prefrontal neural dynamics, with its core innovation lying in time-resolved individualized decoding. This method can significantly improve cognitive function such as interference control while avoiding exposure to unwanted stimuli and has potential for cognitive enhancement and the treatment of psychological disorders such as phobias and post-traumatic stress disorder.

Exposure to microgravity induces abnormal experiences that may affect the perception of time. Head-down tilts (HDTs) are commonly used to investigate the effects of weightlessness. A −30° HDT is considered an appropriate model to simulate the acute phase of microgravity exposure. Temporal performance in a time reproduction task was assessed before and after 30 min of −30° HDT, using 800, 1,000, and 2,000 ms as standard intervals. Absolute error (AE), relative error (ratio), and coefficient of variation (CV) were calculated to quantify performance. Compared to baseline measures obtained prior to HDT, both the mean AE and the ratio were significantly increased after 30 min of −30° HDT at the 800 ms interval. A similar trend was observed at the 1,000 ms interval, but no significant effect was found at the 2,000 ms interval. No significant differences were observed in the CV before and after −30° HDT. Acute exposure to microgravity, simulated by the −30° HDT condition, primarily affects duration perception at sub-second intervals.

Background: Research has shown that visual perceptual learning (VPL) is related to modifying neural activity in higher level decision‐making regions. However, the causal roles of the prefrontal and visual cortexes in VPL are still unclear. Here, we investigated how anodal transcranial direct current stimulation (tDCS) of the prefrontal and visual cortices modulates VPL in the early and later phases and the role of multiple brain regions.Methods: Perceptual learning on the coherent motion direction identification task included early and later stages. After early training, participants needed to continuously train to reach a plateau; once the plateau was reached, participants entered a later stage. Sixty participants were randomly divided into five groups. Regardless of the training at the early and later stages, four groups received multitarget tDCS over the right dorsolateral prefrontal cortex (rDLPFC) and right middle temporal area (rMT), single‐target tDCS over the rDLPFC, and single‐target tDCS over the rMT or sham stimulation, and one group was stimulated at the ipsilateral brain region (i.e., left MT).Results: Compared with sham stimulation, multitarget and two single‐target tDCS over the rDLPFC or rMT improved posttest performance and accelerated learning during the early period. However, multitarget tDCS and two single‐target tDCS led to equivalent benefits for VPL. Additionally, these beneficial effects were absent when anodal tDCS was applied to the ipsilateral brain region. For the later period, the above facilitating effects on VPL induced by multitarget or single‐target tDCS disappeared.Conclusions: This study suggested the causal role of the prefrontal and visual cortices in visual motion perceptual learning by anodal tDCS but failed to find greater beneficial effects by simultaneously stimulating the prefrontal and visual cortices. Future research should investigate the functional associations between multiple brain regions to further promote VPL.

Inhibitory control, as an essential cognitive ability, affects the development of higher cognitive functions. Rhythmic perceptual stimulation has been used to improve cognitive abilities. It is unclear, however, whether it can be used to improve inhibitory control. This study used the Go/NoGo task and the Stroop task to assess various levels of inhibitory control using rhythmic audio-visual stimuli as the stimulus mode. Sixty subjects were randomly divided into three groups to receive 6 Hz, 10 Hz, and white noise stimulation for 30 min. Two tasks were completed by each subject both before and after the stimulus. Before and after the task, closed-eye resting EEG data were collected. The results showed no differences in behavioral and EEG measures of the Go/NoGo task among the three groups. While both 6 Hz and 10 Hz audio-visual stimulation reduced the conflict effect in the Stroop task, only 6 Hz audio-visual stimulation improved the amplitude of the N2 component and decreased the conflict score. Although rhythmic audio-visual stimulation did not enhance response inhibition, it improved conflict inhibition.

Background. In recent years, the incidence of type 2 diabetes mellitus (T2DM) has dramatically increased, imposing a heavy financial burden on society and individuals. The most cost-effective way to control diabetes is diabetes self-management, which depends on patients executive functions (EFs). However, the level of EFs among patients with T2DM varies greatly. In addition to diabetes-related factors contributing to a decline in EFs, trait impulsivity as a relatively stable personality trait may explicate individual differences in EFs. The objective of this study was to verify the mediating effect of negative emotions on the relationship between trait impulsivity and EFs among patients with T2DM in China. Methods. A total of 305 patients with T2DM were enrolled consecutively from the endocrinology departments of three tertiary hospitals in China using convenience sampling. The participants completed the Sociodemographic Questionnaire, Mini-Mental State Examination (MMSE), Barratt Impulsiveness Scale-Brief (BIS-Brief), Depression Anxiety and Stress Scales with 21 items (DASS-21), and Behavior Rating Inventory of Executive Function-Adult (BRIEF-A) version. A structural equation modeling was used to verify the mediating effect of negative emotions on the relationship between trait impulsivity and EFs. Results. A total of 32.46 of the participants experienced at least one aspect of daily EF decline. The mediating effect of trait impulsivity on the Behavioral Regulation Index (BRI) of EFs through negative emotions was significant, accounting for 29.57 of the total effect. The mediating effect of trait impulsivity on the Metacognitive Index (MI) of EFs through negative emotions was significant, accounting for 31.67 of the total effect. Conclusions. Trait impulsivity can positively predict EF decline, which can be alleviated by improving the negative emotions of patients with T2DM. Future research exploring interventions to improve the EFs of patients with T2DM should therefore consider their trait impulsivity and negative emotions.

Military personnel encountered multiple stressful events during the COVID-19 lockdown. Reducing non-combat attrition due to mental disorders is crucial for military morale and combat effectiveness. Grounded in stress theory and regulatory focus theory, this study investigates the influence of resilience on military personnel’s mental health; coping style and regulatory focus are considered potential mediators and moderators, respectively. We conducted a routine psychological assessment on 1,110 military personnel in China. The results indicate that: (1) resilience has a negative impact on the psychological symptoms of military groups; (2) mature and mixed coping styles in military personnel mediate the association between resilience and psychological symptoms; and (3) regulatory focus predominance has a negative moderating effect on mature coping styles’ effects on psychological symptoms. Furthermore, this study supports previous findings that resilience and mental health are interrelated; it demonstrates that military personnel can effectively reduce negative psychological symptoms by improving their resilience level and adopting mature coping styles under stressful situations. The current study presents interventional insights regarding coping styles and mental health from a self-regulatory perspective during the COVID-19 pandemic.

(1) Background: The Go/NoGo task and color-word Stroop task were used to investigate the effect of applying different frequency bands of neural oscillations to the lDLPFC on inhibitory control modulation. (2) Methods: Participants were randomly categorized into four groups and received HD-tACS at 6, 10, and 20 Hz or sham stimulation at 1.5 mA for 20 min. All participants performed a color-word Stroop task and Go/NoGo task before and immediately after the stimulation; closed-eye resting-state EEG signals were acquired for 3 min before and after the tasks. (3) Results: There were no significant differences in the Go/NoGo behavioral indices task across the four groups. In the color-word Stroop task, the Stroop effect of response time was significantly reduced by 6 and 10 Hz stimulations compared to sham stimulation, and the Stroop effect of accuracy was significantly reduced by 10 Hz stimulation. There were no significant differences in the frequency range-specific (delta, theta, alpha, beta, or gamma) resting EEG power before and after stimulation. (4) Conclusions: HD-tACS at 6 and 10 Hz effectively improved participants’ performance on the color-word Stroop task, demonstrating the importance of the lDLPFC in interference inhibition and supporting a causal relationship between theta and alpha oscillations in interference inhibition.

Potential cognitive and physiological alterations due to space environments have been investigated in long-term space flight and various microgravity-like conditions, for example, head-down tilt (HDT), confinement, isolation, and immobilization. However, little is known about the influence of simulated microgravity environments on visual function. Contrast sensitivity (CS), which indicates how much contrast a person requires to see a target, is a fundamental feature of human vision. Here, we investigated how the CS changed by 1-h −30° HDT and determined the corresponding mechanisms with a perceptual template model. A quick contrast sensitivity function procedure was used to assess the CS at ten spatial frequencies and three external noise levels. We found that (1) relative to the + 30° head-up tilt (HUT) position, 1-h −30° HDT significantly deteriorated the CS at intermediate frequencies when external noise was present; (2) CS loss was not detected in zero- or high-noise conditions; (3) HDT-induced CS loss was characterized by impaired perceptual template; and (4) self-reported questionnaires indicated that subjects felt less pleasure and more excitement, less comfort and more fatigued by screen light, less comfort in the area around the eye, and serious symptoms such as piercing pain, blur acid, strain, eye burning, and dizziness after HDT. These findings improve our understanding of the negative effects of simulated microgravity on visual function and elucidate the potential risks of astronauts during space flight.

It has been demonstrated that contrast sensitivity is sensitive to stimulus exposure duration. Here, we investigated how the duration effect on contrast sensitivity was modulated by the spatial frequency and intensity of external noise. Through a contrast detection task, the contrast sensitivity function under 10 spatial frequencies, three external noise, and two exposure duration conditions was measured. The temporal integration effect was defined by the difference in contrast sensitivity or the area under the log contrast sensitivity function between short and long exposure durations. We found that (1) the temporal integration effect was less pronounced in the zero‐noise condition than in the low‐ or high‐noise condition; (2) in the zero‐noise condition, a stronger temporal integration effect was observed at high spatial frequencies; (3) in the high‐noise condition, a stronger temporal integration effect was observed at low spatial frequencies; (4) the spatial‐frequency‐dependent transient or sustained mechanism is also sensitive to external noise level; and (5) perceptual template model analysis revealed that both decreased additive internal noise and an improved perceptual template accounted for the temporal integration effect, and these two factors were tuned to spatial frequency.