Theta Signal Transfer from Parietal to Prefrontal Cortex Ignites Conscious Awareness of Implicit Knowledge during Sequence Learning.

Unconscious acquisition of sequence structure from experienced events can lead to explicit awareness of the pattern through extended practice. Although the implicit-to-explicit transition has been extensively studied in humans using the serial reaction time (SRT) task, the subtle neural activity supporting this transition remains unclear. Here, we investigated whether frequency-specific neural signal transfer contributes to this transition. A total of 208 participants (107 females) learned a sequence pattern through a multisession SRT task, allowing us to observe the transitions. Session-by-session measures of participants' awareness for sequence knowledge were conducted during the SRT task to identify the session when the transition occurred. By analyzing time course RT data using switchpoint modeling, we identified an increase in learning benefit specifically at the transition session. Electroencephalogram (EEG)/magnetoencephalogram (MEG) recordings revealed increased theta power in parietal (precuneus) regions one session before the transition (pretransition) and a prefrontal (superior frontal gyrus; SFG) one at the transition session. Phase transfer entropy (PTE) analysis confirmed that directional theta transfer from precuneus → SFG occurred at the pretransition session and its strength positively predicted learning improvement at the subsequent transition session. Furthermore, repetitive transcranial magnetic stimulation (TMS) modulated precuneus theta power and altered transfer strength from precuneus to SFG, resulting in changes in both transition rate and learning benefit at that specific point of transition. Our brain-stimulation evidence supports a role for parietal → prefrontal theta signal transfer in igniting conscious awareness of implicitly acquired knowledge.SIGNIFICANCE STATEMENT There exists a pervasive phenomenon wherein individuals unconsciously acquire sequence patterns from their environment, gradually becoming aware of the underlying regularities through repeated practice. While previous studies have established the robustness of this implicit-to-explicit transition in humans, the refined neural mechanisms facilitating conscious access to implicit knowledge remain poorly understood. Here, we demonstrate that prefrontal activity, known to be crucial for conscious awareness, is triggered by neural signal transfer originating from the posterior brain region, specifically the precuneus. By employing brain stimulation techniques, we establish a causal link between neural signal transfer and the occurrence of awareness. Our findings unveil a mechanism by which implicit knowledge becomes consciously accessible in human cognition.

The effects of forewarning and divided attention on context retrieval in false recognition.

After studying a list of words that are semantically associated to a critical lure, participants are more likely to attribute a falsely recognised critical lure to the context of its strong than weak semantic associates. This is known as the source-strength effect. The current study investigated the roles of automatic and controlled processing in context retrieval in false recognition that is demonstrated by the source-strength effect. The results revealed that the source-strength effect was impervious to forewarning (Experiment 1) and remained intact when attentional resources at encoding were reduced (Experiment 2), suggesting that context retrieval in false recognition is based on automatic processes that are not amenable to conscious control and do not require many attentional resources. This interpretation is consistent with the associative activation theory, which proposes that context retrieval in false recognition is based on memory associations between contexts and critical lures that are automatically created when critical lures become automatically activated via spreading activation process.

Dissociating value-based neurocomputation from subsequent selection-related activations in human decision-making.

Human decision-making requires the brain to fulfill neural computation of benefit and risk and therewith a selection between options. It remains unclear how value-based neural computation and subsequent brain activity evolve to achieve a final decision and which process is modulated by irrational factors. We adopted a sequential risk-taking task that asked participants to successively decide whether to open a box with potential reward/punishment in an eight-box trial, or not to open. With time-resolved multivariate pattern analyses, we decoded electroencephalography and magnetoencephalography responses to two successive low- and high-risk boxes before open-box action. Referencing the specificity of decoding-accuracy peak to a first-stage processing completion, we set it as the demarcation and dissociated the neural time course of decision-making into valuation and selection stages. The behavioral hierarchical drift diffusion modeling confirmed different information processing in two stages, that is, the valuation stage was related to the drift rate of evidence accumulation, while the selection stage was related to the nondecision time spent in response-producing. We further observed that medial orbitofrontal cortex participated in the valuation stage, while superior frontal gyrus engaged in the selection stage of irrational open-box decisions. Afterward, we revealed that irrational factors influenced decision-making through the selection stage rather than the valuation stage.

Neural Basis of the Implicit Learning of Complex Artificial Grammar with Nonadjacent Dependencies.

The capacity for the implicit learning/processing of complex grammar with nonadjacent dependencies is an important feature of human language learning. In this fMRI study, using an implicit AGL paradigm, we explored the neural basis of the implicit learning of the nonadjacent dependency rule, disentangling from sequence-based chunk knowledge (i.e., local sequential regularities or substring) by focusing on the low chunk strength items (which were naturally less similar to training strings), based on tracking neural responses during training and test phases. After listening to and memorizing a series of strings of 10 syllables generated from nonadjacent artificial grammar in the training phase, participants implicitly acquired the knowledge of grammar and chunks. Regarding grammaticality, Broca's area was specifically related to low chunk strength grammatical strings relative to nongrammatical strings in the test phase. This region showed decreased activity with time in the training phase, and a lesser decrease in activity was associated with higher performance in grammar learning. Furthermore, Broca's area showed significantly higher strength of functional connectivity with the left superior temporal gyrus in the low chunk strength grammatical string compared with nongrammatical strings, and this functional connectivity increased with the training time. For the chunks, the performance of accurate discrimination of high chunk strength from low chunk strength nongrammatical strings was predicted by hippocampal activity in the training phase. Converging evidence from the training and test phases showed that Broca's area and its functional connectivity with the left superior temporal gyrus were engaged in the implicit learning/processing of the nonadjacent dependency rule, separating the effects of chunks.

The neural mechanisms underlying the modulation of attentional deployment on emotional stability.

Emotional stability, the change of emotion response among situations, was associated with mental illness, such as depression. The current study aimed to explore the modulation of attentional deployment on emotional stability by combining functional magnetic resonance imaging (fMRI) and a sequential risk-taking task. During the task, participants were asked to open a series of boxes consecutively and decided when to stop. Each box contained a reward, except one containing a devil to zero reward in the trial. When participants stopped, both collected gains and missed chances were revealed. The attentional deployment was manipulated during the outcome feedback, i.e., inducing participants to focus on the good part (GF context) or the bad part (MF context) of the decision outcome. Besides, the Control context was also set, in which the attentional deployment was not manipulated. The behavioral results showed that the emotional stability was stronger in GF context relative to MF and Control contexts. At the neural level, with outcomes getting better, activations of ventral striatum (VS) and superior frontal gyrus (SFG) increased faster in GF context than that in MF and Control contexts. In addition, in GF context, the changing of SFG activation with outcomes getting better was associated with emotional stability. The current study highlighted that focusing on the good part of decision outcomes could enhance emotional stability effectively and SFG played a vital role in this process.

Altered neural responses to missed chance contribute to the risk-taking behaviour in individuals with Internet gaming disorder.

Missed chance is a powerful factor in shaping risk-taking behaviour. The abnormal risk-taking behaviour is an obvious feature of individuals with Internet gaming disorder (IGD). However, the relationship between the neural responses to missed chance and risk-taking behaviour in IGD individuals remains unclear. In the current fMRI study, 28 IGD subjects (12 female, 23.04 ± 2.43 years old) and 26 healthy control (HC) subjects (13 female, 23.58 ± 2.67 years old) participated in fMRI scanning during performance of a sequential risk-taking task. The general linear model and the psycho-physiological interaction analyses were conducted to explore the difference in neural responses between the two groups. The results showed that IGD subjects reported more regret for the large missed chance and took more risk than HC subjects. Moreover, compared with HC subjects, IGD subjects exhibited greater activations in brain regions like ventral striatum (VS) and superior frontal gyrus (SFG), and stronger VS-thalamus functional connectivity for the large missed chance. Additionally, among IGD subjects, the SFG activation for the large missed chance was positively correlated with the risk-taking behaviour. Together, the results revealed the altered neural responses to missed chance contributed to the risk-taking behaviour in IGD individuals. The findings could help to clearly understand why IGD individuals continue playing online games despite the risks of widely known and could provide a new perspective for the intervention of IGD.

Evidence-Based Classification in Powerchair Football: Determining the Determinants.

The purpose of this study was to initiate the development of an evidence-based sport classification system for powerchair football, a sport that serves athletes with physical impairments. Sport classification is designed to increase participation by minimizing the impact of impairment on competition outcome, and powerchair football lacks an evidence-based system of classification which is required of Paralympic sports. A number of approaches were used to build the theoretical model of sport performance (Step 2 of the International Paralympic Committee model). Key sport activities were identified through surveys of stakeholders and underlying determinants of those key activities were identified through game and database analyses. Current findings support drive control, ball control, communication, and adjustment to the ball as key activities in powerchair football with joint-specific strength and range of motion, sensory, and neurological variables identified as underlying determinants.

Empathy-based tolerance towards poor norm violators in third-party punishment.

Third-party punishment (TPP) plays an important role in fairness norm enforcement. This study investigated how the economic status of proposers could modulate third parties' behavioural and neural responses to unfairness. Participants played a TPP game as third parties deciding whether to punish proposers after observing the offers from proposers while behavioural and electroencephalogram (EEG) data were recorded. The proposers were of either high economic status or low economic status, and the recipients were middle class. The behavioural results indicated that participants reported decreased punishment for poor-proposed unfair offers compared to rich-proposed unfair offers, and this effect was stronger for highly unfair offers. Neurally, greater P200, a component involved in empathy processing, was observed in response to highly unfair offers (i.e. 90:10 and 80:20) proposed by the poor, suggesting that when the targets of severe punishments were poor proposers, participants showed greater empathy for poor norm violators in highly unfair trials. Taken together, these findings help to elucidate that the third-parties tend to tolerate the norm-violating behaviours conducted by the poor and provided further neuroscience evidence for the influence of economic status of proposers on TPP.

Evaluation of work resumption strategies after COVID-19 reopening in the Chinese city of Shenzhen: a mathematical modeling study.

OBJECTIVES: As China is facing a potential second wave of the epidemic, we reviewed and evaluated the intervention measures implemented in a major metropolitan city, Shenzhen, during the early phase of Wuhan lockdown. STUDY DESIGN: Based on the classic SEITR model and combined with population mobility, a compartmental model was constructed to simulate the transmission of COVID-19 and disease progression in the Shenzhen population. METHODS: Based on published epidemiological data on COVID-19 and population mobility data from Baidu Qianxi, we constructed a compartmental model to evaluate the impact of work and traffic resumption on the epidemic in Shenzhen in various scenarios. RESULTS: Imported cases account for most (58.6%) of the early reported cases in Shenzhen. We demonstrated that with strict inflow population control and a high level of mask usage after work resumption, various resumptions resulted in only an insignificant difference in the number of cumulative infections. Shenzhen may experience this second wave of infections approximately two weeks after the traffic resumption if the incidence risk in Hubei is high at the moment of resumption. CONCLUSION: Regardless of the work resumption strategy adopted in Shenzhen, the risk of a resurgence of COVID-19 after its reopening was limited. The strict control of imported cases and extensive use of facial masks play a key role in COVID-19 prevention.

Down-regulation of lncRNA CASC9 aggravates sepsis-induced acute lung injury by regulating miR-195-5p/PDK4 axis.

BACKGROUND: Long non-coding RNA (lncRNA) cancer susceptibility candidate 9 (CASC9) is reported to be linked to cancers. This research aims to explore the role and possible mechanism of CASC9 in lung injury induced by sepsis. METHODS: Lipopolysaccharide (LPS) induced human small airway epithelial cells (HSAECs) were established in vitro to mimic sepsis-induced lung injury. The effects of CASC9 and miR-195-5p on HSAECs viability were studied by CCK-8 assay. Interactions between CASC9 and miR-195-5p were determined by bioinformatics analysis, RT-PCR, dual luciferase reporter assay, and RNA immunoprecipitation assay. Pyruvate dehydrogenase kinase 4 (PDK4) and apoptosis-related molecules including Bcl2 and Bad were detected by western blot. Additionally, sepsis-induced lung injury model in rats was established by intraperitoneal injection of LPS in vivo to validate the demonstrations of in vitro studies. RESULTS: CASC9 was markedly down-regulated while miR-195-5p was significantly up-regulated in HSAECs treated by LPS and lung tissues of rats with sepsis. CASC9 interacted with miR-195-5p, and negatively regulated its expression level. Overexpression of CASC9 or transfection of miR-195-5p inhibitors significantly promoted the viability of HSAECs. The transfection of miR-195-5p mimics effected oppositely. For mechanism, miR-195-5p targeted the 3'UTR of pyruvate dehydrogenase kinase 4 (PDK4) gene and depressed the protein level, and PDK4 was regulated indirectly by CASC9. Restoration of CASC9 in the lung tissues of rats with sepsis ameliorated lung injury. CONCLUSION: CASC9 protects lung epithelial cells from sepsis-induced injury via regulating miR-195-5p/PDK4 axis.

Attenuated self-serving bias in people with internet gaming disorder is related to altered neural activity in subcortical-cortical midline structures.

BACKGROUND: To protect and maintain the positivity of self-concept, normal people usually show a self-serving bias (internal attribution of positive events and external attribution of negative events) by the motives of self-enhancement and self-protection. Additionally, self-serving assessments predominantly activate the subcortical-cortical midline structures (CMS) in healthy individuals. However, little is known about self-serving bias and its underlying neural correlates among individuals with Internet gaming disorder (IGD). METHODS: Twenty-four participants with IGD and 25 recreational Internet gaming users (RGUs) were scanned while attributing the causes of positive/negative self- and other-related events that could occur in both the game-world and real-world contexts. Region-of-interest (within CMS regions) and parametric analysis were performed to investigate the neural correlates of self-serving bias in IGD. RESULTS: Behaviorally, the IGD participants attributed more negative and fewer positive events to themselves than RGU participants in both contexts. Neurally, during the attributions of negative events, the IGD participants exhibited increased ventromedial prefrontal cortex (vmPFC) activation in both contexts compared with RGU participants. Higher vmPFC activation was associated with weaker self-protective motivation in the IGD group. Meanwhile, during the attributions of positive events, the IGD participants exhibited decreased precuneus/posterior cingulate cortex activation in the real world compared with RGU participants. Parametric analysis showed a reduced positive correlation between precuneus activation and self-attribution ratings of positive events in the real world in the IGD group relative to the RGU group. CONCLUSION: These results suggest that individuals with IGD show an attenuated self-serving bias and altered brain activity within CMS regions involved in self-attribution, providing evidence for the negative self-concept and weakened abilities in both self-enhancement and self-protection in IGD.

Correction to: Attenuated self-serving bias in people with internet gaming disorder is related to altered neural activity in subcortical-cortical midline structures.

An amendment to this paper has been published and can be accessed via the original article.

Responsibility modulates the neural correlates of regret during the sequential risk-taking task.

Responsibility is a necessary prerequisite in the experience of regret. The present fMRI study investigated the modulation of responsibility on the neural correlates of regret during a sequential risk-taking task. Participants were asked to open a series of boxes consecutively and decided when to stop. Each box contained a reward, except for one containing a devil to zero participant's gain in the trial. Once participants stopped, both collected gains and missed chances were revealed. We manipulated responsibility by setting two different contexts. In the Self (high responsibility) context, participants opened boxes and decided when to stop by themselves. In the Computer (low responsibility) context, a computer program opened boxes and decided when to stop for participants. Before each trial, participants were required to decide whether it would be a Self or a Computer context. Behaviorally, participants felt less regret (more relief) for gain outcome and more regret for the loss outcome in the high-responsibility context than low responsibility context. At the neural level, when experiencing a gain, high-responsibility trials were characterized by stronger activation in mPFC, pgACC, mOFC, and striatum with decreasing number of missed chances relative to low responsibility trials. When experiencing a loss, low responsibility trials were associated with stronger activation in dACC and bilateral insula than high-responsibility trials. Conversely, during a loss, high-responsibility trials showed more striatum activity than low responsibility trials. These results highlighted the sensitivity of the frontal region, striatum, and insula to changes in level of responsibility.

Modulation of financial deprivation on deception and its neural correlates.

Deception is a universal phenomenon in human society and plays an important role in everyday life. Previous studies have revealed that people might have an internalized moral norm of keeping honest and the deceptive behavior was reliably correlated with activation in executive brain regions of prefrontal cortices to over-ride intuitive honest responses. Using functional magnetic resonance imaging, this study sought to investigate how financial position modulated the neural responses during deceptive decision. Twenty-one participants were scanned when they played a series of adapted Dictator Game with different partners after a ball-guess game. Specifically, participants gained or lost money in the ball-guess game, and had opportunities to get more financial gains through cheating in the following adapted Dictator Game. Behavioral results indicated that participants did not cheat to the full extent; instead they were more likely to lie after losing money compared with gaining money. At the neural level, weaker activities in the dorsolateral prefrontal cortices were observed when participants lied after losing money than gaining money. Together, our data indicated that, people really had an internalized norm of keeping honest, but it would be lenient when people feel financial deprivation. And suppressing the truthful response originating from moral norm of keeping honest was associated with increased level of activation in the dorsolateral prefrontal cortices, but this association became weaker when people were under financial deprivation.

Perceived reputation of others modulates empathic neural responses.

Empathy enables us to understand and share the emotional and affective states of another person and plays a key role in social behaviors. The current study investigated whether and how empathic neural responses to pain were modulated by the perceived reputation of others. Action histories reflecting individuals' past cooperation or betrayal actions in the repeated prisoner's dilemma game were introduced as an index of reputation. We assessed brain activity with functional magnetic resonance imaging while the participants observed individuals with a good or bad reputation receiving or not receiving pain. The results indicated that the participants exhibited reduced empathic responses in AI and dACC to the individual who had a bad reputation relative to the one who had a good reputation, suggesting that their empathy for pain was modulated by the perceived reputation of others.

Incidental self-processing modulates the interaction of emotional valence and arousal.

The middle insula has been associated with incidental self-processing of negative information elicited by individual's handwriting. However, emotional valence and arousal have been proved to work in an interactive way and located in middle insula. The present functional magnetic resonance imaging study used participant's handwritings as material to explore how incidental self-processing affected the interaction of valence and arousal and its neural basis. Each participant was asked to read silently emotional and neutral words written by himself/herself or the other person. The right middle insula as well as the left putamen showed greater activations in response to emotional stimuli evoking conflicting approach-withdrawal tendencies (i.e., positive high-arousal and negative low-arousal words) relative to stimuli evoking congruent approach versus withdrawal tendencies (i.e., positive low-arousal and negative high-arousal words), whereas a reverse activation pattern in these two regions was observed during processing other-handwriting. The current study indicated that incidental self-processing modulates the interaction of emotional valence and arousal.

The neural basis of implicit learning of task-irrelevant Chinese tonal sequence.

The present study sought to investigate the neural basis of implicit learning of task-irrelevant perceptual sequence. A novel SRT task, the serial syllable identification task (SSI task), was used in which the participants were asked to recognize which one of two Chinese syllables was presented. The tones of the syllables were irrelevant to the task but followed an underlying structured sequence. Participants were scanned while they performed the SSI task. Results showed that, at the behavioral level, faster RTs for the sequential material indicated that task-irrelevant sequence knowledge could be learned. In the subsequent prediction test of knowledge of the tonal cues using subjective measures, we found that the knowledge was obtained unconsciously. At the neural level, the left caudate, bilateral hippocampus and bilateral superior parietal lobule were engaged during the sequence condition relative to the random condition. Further analyses revealed that greater learning-related activation (relative to random) in the right caudate nucleus, bilateral hippocampus and left superior parietal lobule were found during the second half of the training phase compared with the first half. When people reported that they were guessing, the magnitude of the right hippocampus and left superior parietal lobule activations was positively related to the accuracy of prediction test, which was significantly better than chance. Together, the present results indicated that the caudate, hippocampus and superior parietal lobule played critical roles in the implicit perceptual sequence learning even when the perceptual features were task irrelevant.

An Empirical Investigation of the Relationships Among Self-Esteem, Depression and Self-Serving Bias in People with Internet Gaming Disorder.

Introduction: People are generally characterized by a self-serving bias which describes the tendency to ascribe positive outcomes or success to internal or personal causes (self-enhancement motivation) and ascribe negative outcomes or failure to external or situational causes (self-protection motivation). It has been found that the individuals with internet gaming disorder (IGD) who have low self-esteem and high depression exhibit an attenuated self-serving bias. However, the relationships among self-esteem, depression and self-serving bias are not clearly identified. Methods: A sample of 138 IGD participants completed self-esteem and depression scales and a causal attribution task (Study 1) to examine the relationships among self-esteem, depression and self-serving bias (both self-enhancement and self-protection). In follow-up Study 2, 28 IGD participants were recruited to undertake self-affirmation intervention which can affirm one's sense of global self-view and bolster self-esteem to explore whether self-affirmation would trigger a reduction of depression and a raise of self-serving bias. Results: The results of path analysis in Study 1 showed that the self-serving bias was predicted by self-esteem and depression, and the depression played a mediating role between self-esteem and self-serving bias. The results of Study 2 showed that the IGD participants reported higher self-esteem, lower depression and engaged in more self-protection motivation after affirming-self manipulation as compared with affirming-other manipulation. Conclusion: These findings suggest that self-esteem predicts self-serving bias through depression and self-affirmation could trigger an increase of self-esteem, further decrease depression and improve self-serving bias for the individuals with IGD. The present article clearly identified the relationships among these factors and provided a new approach to promote positive self-concept in individuals with IGD. Future research is warranted to explore the lasting benefits of self-affirmation on domains of education, relationships and gaming withdrawal for the individuals with IGD among different populations.

"One for two" strategy to construct an organic-inorganic polymer colloid for flame-retardant modification of flax fabric and rigid polyurethane foam.

Polymeric materials such as fabric and foam have high flammability which limits their application in the field of fire protection. To this end, an organic-inorganic polymer colloid constructed from carboxymethyl chitosan and ammonium polyphosphate was used to improve the flame retardancy of flax fabric (FF) and rigid polyurethane foam (RPUF) based on a "one for two" strategy. The modification processes of FF and RPUF relied on pad-dry-cure method and UV-curing technology, respectively, and the modified FF and RPUF were severally designated as CMC/APP-FF and RFR-RPUF. Flame retardancy studies showed that CMC/APP-FF and RFR-RPUF exhibited limiting oxygen index values as high as 39.4 % and 42.6 %, respectively, and both achieved self-extinguishing when external ignition source was removed. Thermogravimetric analysis and cone calorimetry test confirmed that CMC/APP-FF and RFR-RPUF had good charring ability and demonstrated reduced peak heat release rate values of 90.1 % and 10.8 %, respectively, distinct from before they were modified. In addition, condensed phase analysis showed that after burning, CMC/APP-FF became an integration char structure, whereas RFR-RPUF turned into a sandwiched char structure. In summary, the "one for two" strategy reported in this work provides new insights for the economical fabrication of flame-retardant polymeric materials.

Increased neural responses to unfairness in a loss context.

Unfairness plays an important role in economic decision making. This fMRI study sought to investigate how the loss and the gain contexts could modulate behavioral and brain responses to unfairness by focusing on participants' rejection behaviors during an Ultimatum Game paradigm. Participants were scanned while they were playing the Ultimatum Game as responders in both loss and gain contexts, i.e. receiving ¥50 as gains and paying for ¥50 as losses. At the behavioral level, lower fairness ratings and higher rejection rates were revealed for unfair losses than unfair gains. At the neural level, left dorsolateral prefrontal cortex, bilateral anterior insula, anterior cingulate cortex/anterior middle cingulate cortex and bilateral dorsal striatum were associated with rejection (vs. acceptance) in the loss context, but not in the gain context. Together, our data indicated that participants may experience more unfairness in UG and stronger desire to sanction social norm violations in the loss context than in the gain context, inducing more fairness-related neutral activities when rejecting (vs. accepting) unfair losses than unfair gains. These findings shed light on the significance of context (i.e. loss or gain) in fairness-related social decision-making processes.