Anodal online transcranial direct current stimulation facilitates visual motion perceptual learning.

Visual perceptual learning (VPL) has great potential implications for clinical populations, but adequate improvement often takes weeks to months to obtain; therefore, practical applications of VPL are limited. Strategies that enhance visual performance acquisition make great practical sense. Transcranial direct current stimulation (tDCS) could be beneficial to VPL, but thus far, the results are inconsistent. The current study had two objectives: (1) to investigate the effect of anodal tDCS on VPL and (2) to determine whether the timing sequence of anodal tDCS and training influences VPL. Anodal tDCS was applied on the left human middle temporal (hMT+) during training on a coherent motion discrimination task (online), anodal tDCS was also applied before training (offline) and sham tDCS was applied during training (sham). The coherent thresholds were measured without stimulation before, 2 days after and 1 month after training. All participants trained for five consecutive days. Anodal tDCS resulted in more performance improvement when applied during daily training but not when applied before training. Additionally, neither within-session improvement nor between-session improvement differed among the online, offline and sham tDCS conditions. These findings contribute to the development of efficient stimulation protocols and a deep understanding of the mechanisms underlying the effect of tDCS on VPL.

Posttraining anodal tDCS improves early consolidation of visual perceptual learning.

OBJECTIVE: We aimed to investigate the transcranial direct current stimulation (tDCS)-induced facilitation of early consolidation over a period of extended training sessions and explored the effect of tDCS on visual perceptual learning (VPL) improvement during online learning and offline consolidation. METHODS: In the current double-blind sham-controlled study, twenty-four healthy participants were trained on coherent motion direction identification for 5 consecutive sessions. Performance was assessed at the pre- and posttests. Anodal or sham tDCS of the left human middle temporal region (hMT+) was applied immediately after the completion of daily training (termed early consolidation). RESULTS: The magnitude of improvement between anodal and sham tDCS was marginally significant, supporting the beneficial effect of anodal tDCS on VPL by stimulating early consolidation. Additionally, anodal tDCS induced a larger improvement between the first two training sessions than sham tDCS. No effect of anodal tDCS was found on the within-session improvement. CONCLUSIONS: The above results indicated that anodal tDCS facilitates offline consolidation during the early period of the whole training series, not online learning. The possible neural mechanisms and limitations (sample size and persistent effects) were discussed. SIGNIFICANCE: Our findings support the use of the combination of tDCS and behavioral training in facilitating visual rehabilitation and contribute to a deeper understanding of learning processes by neuromodulation procedures.

Comprehensive analysis of the DNA-binding specificity of an Aspergillus nidulans transcription factor, AmyR, using a bead display system.

The in vitro DNA binding profile of Aspergillus nidulans transcription factor AmyR was analyzed by a novel approach employing a genetic library of beads and flow cytometry analysis. An artificial library with 22 randomized nucleotides was constructed and subjected to a protein-DNA binding reaction with MalE-tagged AmyR. DNA fragments with potential AmyR-binding sites were labeled with fluorescence-conjugated antibody to be enriched by flow cytometry through 5 rounds of successive selection. Finally, a binding motif with a single CGG triplet was obtained from DNA fragments showing weak AmyR binding, while another motif with dual CGG triplets was discovered with stronger binding fragments. An informative motif, CGGNNNTTTNTCGG, was found to exist only in the promoter region of highly AmyR-dependent genes. These results suggest that this system is a powerful tool for the rapid and comprehensive analysis of the binding preferences of transcription factors.

The relationship between dimensions of empathy and symptoms of depression among university students during the COVID-19 pandemic: A network analysis.

Background: The relationship between different dimensions of empathy and individual symptoms of depression during the COVID-19 pandemic remains unclear, despite the established link between empathy and depression. The network analysis offers a novel framework for visualizing the association between empathy and depression as a complex system consisting of interacting nodes. In this study, we investigated the nuanced associations between different dimensions of empathy and individual symptoms of depression using a network model during the pandemic. Methods: 1,177 students completed the Chinese version of the Interpersonal Reactivity Index (IRI), measuring dimensions of empathy, and the Chinese version of the Patient Health Questionnaire-9 (PHQ-9), measuring symptoms of depression. First, we investigated the nuanced associations between different dimensions of empathy and individual depressive symptoms. Then, we calculated the bridge expected influence to examine how different dimensions of empathy may activate or deactivate the symptoms of depression cluster. Finally, we conducted a network comparison test to explore whether network characteristics such as empathy-depression edges and bridge nodes differed between genders. Results: First, our findings showed that personal distress was positively linked to symptoms of depression. These symptoms involved psychomotor agitation or retardation (edge weight = 0.18), sad mood (edge weight = 0.12), trouble with concentrating (edge weight = 0.11), and guilt (edge weight = 0.10). Perspective-taking was found to be negatively correlated with trouble with concentrating (edge weight = -0.11). Empathic concern was negatively associated with suicidal thoughts (edge weight = -0.10) and psychomotor agitation or retardation (edge weight = -0.08). Fantasy was not connected with any symptoms of depression. Second, personal distress and empathic concern were the most positive and negative influential nodes that bridged empathy and depression (values of bridge expected influence were 0.51 and -0.19 and values of predictability were 0.24 and 0.24, respectively). The estimates of the bridge expected influence on the nodes were adequately stable (correlation stability coefficient = 0.75). Finally, no sex differences in the studied network characteristics were observed. Conclusions: This study applied network analysis to reveal potential pathways between different dimensions of empathy and individual symptoms of depression. The findings supported the existing theoretical system and contribute to the theoretical mechanism. We have also made efforts to suggest interventions and preventions based on personal distress and empathic concern, the two most important dimensions of empathy for depressive symptoms. These efforts may help Chinese university students to adopt better practical methods to overcome symptoms of depression during the COVID-19 pandemic.

High-definition transcranial direct current stimulation of the left middle temporal complex does not affect visual motion perception learning.

Visual perceptual learning (VPL) refers to the improvement in visual perceptual abilities through training and has potential implications for clinical populations. However, improvements in perceptual learning often require hundreds or thousands of trials over weeks to months to attain, limiting its practical application. Transcranial direct current stimulation (tDCS) could potentially facilitate perceptual learning, but the results are inconsistent thus far. Thus, this research investigated the effect of tDCS over the left human middle temporal complex (hMT+) on learning to discriminate visual motion direction. Twenty-seven participants were randomly assigned to the anodal, cathodal and sham tDCS groups. Before and after training, the thresholds of motion direction discrimination were assessed in one trained condition and three untrained conditions. Participants were trained over 5 consecutive days while receiving 4 × 1 ring high-definition tDCS (HD-tDCS) over the left hMT+. The results showed that the threshold of motion direction discrimination significantly decreased after training. However, no obvious differences in the indicators of perceptual learning, such as the magnitude of improvement, transfer indexes, and learning curves, were noted among the three groups. The current study did not provide evidence of a beneficial effect of tDCS on VPL. Further research should explore the impact of the learning task characteristics, number of training sessions and the sequence of stimulation.