Left superior parietal lobe mediates the link between spontaneous mind-wandering tendency and task-switching performance.

While increasing studies have documented the link between mind wandering and task switching, less is known about which brain regions mediate this relationship. Using the MPI-Leipzig Mind-Brain-Body dataset (N = 173), we investigated the association between trait-level tendencies of mind wandering, task-switching performance, structural connectivity, and resting-state functional connectivity. At the behavioral level, we found that higher spontaneous mind-wandering trait scores were associated with shorter reaction times on both repeat and switch trials. The whole brain cortical thickness analysis revealed a strong mediating role of the left superior parietal lobe, which is part of the dorsal attention network, in the link between spontaneous mind-wandering tendency and task-switching performance. The resting-state functional connectivity analysis further demonstrated that this association was partly mediated by the negative dorsal attention network-default mode network functional connectivity. No significant mediating effects were found for deliberate mind-wandering tendency. Overall, the findings highlight the pivotal role of the left superior parietal lobe in activating new mental set during mind-wandering and task-switching processes, providing another evidence in favor of a role for switching in mind wandering.

Commonalities between mind wandering and task-set switching: An event-related potential study.

Previous research has established that mind wandering does not necessarily disrupt one's task-switching performance. Here we investigated the effects of mind wandering on electrophysiological signatures, measured using event-related potentials (ERPs), during a switching task. In the current study, a final sample of 22 young adults performed a task-switching paradigm while electroencephalography was continuously recorded; mind wandering was assessed via thought probes at the end of each block. Consistent with previous research, we found no significant disruptive effects of mind wandering on task-switching performance. The ERP results showed that at the posterior electrode sites (P3, Pz, and P4), P3 amplitude was higher for mind-wandering switch trials than on-task switch trials, thus opposing the typical pattern of P3 attenuation during periods of mind wandering relative to on-task episodes. Considering that increased P3 amplitude during higher-order switch trials (e.g., response rule switching) may reflect the implementation of new higher-order task sets/rules, the current findings seem to indicate similar executive control processes underlie mind wandering and task-set switching, providing further evidence in favor of a role for switching in mind wandering.

The influence of cognitive control on the processing of L2 garden path sentence among Chinese-English bilinguals.

Few studies have examined the role of cognitive control in processing ambiguity, let alone the roles of different components of cognitive control. In the current study, the English (L2) Sentence Processing Task and a series of cognitive control tasks were administered among 111 young adult Chinese-English bilinguals to investigate the influence of different components of cognitive control on garden path sentence comprehension, with other factors such as age, socio-economic status, and language proficiency strictly matched. Data analysis results showed a significant garden path effect on response times (RTs) and accuracy among all the participants. The results of independent t-test analyses revealed that the high working memory (WM) group was faster in ambiguity resolution, and so was the high monitoring group. However, there were no differences between the high and low inhibition and shifting groups in ambiguity resolution. These findings reveal that only certain aspects of cognitive control influence garden path sentence comprehension.

Spontaneous mind-wandering tendencies linked to cognitive flexibility in young adults.

Despite that previous studies have investigated mind wandering using task-switching paradigms, the association between the tendency to mind wander and cognitive flexibility remains largely unexplored. The present study investigated the relationship between self-reported spontaneous mind-wandering tendencies and task-switching performance in young adults. Seventy-nine university students performed a forced task-switching and a voluntary task-switching paradigm and then completed a battery of questionnaires. The results showed that compared to participants with lower spontaneous mind-wandering tendencies, participants with higher spontaneous mind-wandering tendencies demonstrated better performance (evidenced by smaller switch cost reaction times) in the forced task-switching paradigm despite indicating more mind wandering during task performance. Performance on the voluntary task-switching paradigm, on the other hand, did not differ between the two groups. The findings in the forced task-switching paradigm indicate a link between mind wandering and cognitive flexibility, thus providing initial evidence in favor of a role for switching in mind wandering.

Differential impacts of natural L2 immersion and intensive classroom L2 training on cognitive control.

The relationship between bilingualism and cognitive control has been controversial. We believe that the discrepant findings are likely driven by the complexities of the bilingual experience, which is consistent with the Adaptive Control Hypothesis. The current study investigates whether the natural language immersion experience and the classroom intensive language training experience have differential impacts on cognitive control. Among unbalanced Chinese-English bilingual students, a natural L2 (second language) immersion group, an L2 public speaking training group, and a control bilingual group without immersion or training experience were compared on their cognitive control abilities, with the participants' demographic factors strictly controlled. The results showed that the L2 immersion group and the L2 speaking group had faster speed than the control group in the Flanker task, whereas the L2 immersion group had fewer errors than the other two groups in the Wisconsin Card Sorting Test (WCST). These results generally provide evidence in favour of the Adaptive Control Hypothesis, specifying that natural L2 immersion and L2 public speaking training experiences are distinctively related to cognitive control. The current study is the first of its kind to link specific bilingual experiences (natural L2 immersion vs. intensive L2 public speaking) with different components of cognitive control.

Bilingualism, Demographics, and Cognitive Control: A Within-Group Approach.

Previous studies have suggested a bilingual advantage in cognitive control as a result of the bilinguals' language experience. However, the results are controversial as there are various factors (language proficiency, SES, culture, and intelligence, etc.) affecting cognitive control. In the current study, after between-group comparisons, we adopted a within-group approach by multiple regressions to investigate whether the performance by 10-to-75-year-old participants (N = 91) of tasks measuring inhibition, monitoring, and mental set shifting could be predicted by bilingualism, or demographic factors, or both. The results of multiple stepwise regression analyses showed that L2 proficiency was a significant predictor for conflict monitoring and inhibition, education and age were significant predictors for mental set shifting, and SES was a minor predictor for inhibition. These findings provide evidence that cognitive control is affected by both bilingualism and demographic factors. Future studies are encouraged to further identify the relationship between bilingualism and cognitive control from specific bilingual experience.

Effectiveness of executive function training on mental set shifting, working memory and inhibition in healthy older adults: A double-blind randomized controlled trials.

AIMS: The aim of this study was to evaluate the effectiveness of executive function training on mental set shifting, working memory and inhibition for healthy older adults. BACKGROUND: Executive functions control and guide individuals' behaviours through a top-down cognitive model and have been regarded as the exhibition and integration of various high-level cognitive functions. However, prior studies have rarely focused on the subcomponent indicators of executive function, such as mental set shifting, working memory and inhibition in healthy older adults. DESIGN: Randomized controlled trial. METHODS: A total of 62 participants were recruited between January 2015 - March 2017, with both groups attending a 30-min training session three times per week for 8 weeks. Executive function training group received the training content that focused on the mental set shifting, working memory and inhibition. Active control group engaged in passive information activities. The primary outcome was mental set shifting, measured by the Wisconsin card sort test. The secondary outcomes were working memory measured by digit span and inhibition measured by the Stroop color word test. RESULTS: The executive function training group had statistically significant higher scores of mental set shifting and working memory at immediate follow-up and that its effect on mental set shifting could be maintained for 3-6 months. However, this training did not have any statistically significant results on inhibition. CONCLUSION: The executive function training may be an effective preventive intervention for healthy older adults. Future studies are recommended to include a broader range of participants with different levels of cognitive function.

Relations between key executive functions and aggression in childhood.

The present study examined relationships between three key executive functions (working memory, inhibition, and mental set-shifting) and multiple types of aggression in a general population sample of 9-year-old children. One hundred and forty-eight children completed a battery of executive function tasks and were rated on aggression by their primary teachers. All executive function (EF) composites were related to a composite measure of aggression. Working memory (WM) was most consistently related to the different types of aggression (overt, relational, reactive, and proactive), whereas inhibition and mental set-shifting only were related to relational and reactive aggression, respectively. Specificity in relations (studied as independent contributions) was generally low with the exception of the relation between WM and relational aggression. Taken together, our results highlight the roles of WM and relational aggression in EF-aggression relations in middle childhood.

Disproportionate Decline of Executive Functions in Early Mild Cognitive Impairment, Late Mild Cognitive Impairment, and Mild Alzheimer's Disease.

BACKGROUND AND PURPOSE: Many literatures indicate that executive dysfunction exists in mild cognitive impairment (MCI) as well as Alzheimer's disease (AD). However, there are few studies that found how early the deficits of the executive function (EF) exist in MCI. The present study investigated the presence of executive dysfunctions in the earliest stage of MCI, and the sub-domains of EF which are disproportionately impaired earlier than others. METHODS: The participants were 41 normal elderly (NE), 86 with amnestic multi-domain MCI, and 41 with mild AD. The MCI group was further sub-divided into two groups: Early MCI (EMCI, n=45) and late MCI (n=41), based on the Clinical Dementia Rating-Sum of Boxes. All participants were given neuropsychological tests to assess the sub-domains of EF, such as verbal fluency, psychomotor speed, inhibitory control, and mental set-shifting. RESULTS: Impairment of semantic fluency was observed in EMCI, with gradual worsening as cases approached mild AD. Phonemic fluency and psychomotor speed were also impaired at the early stage of MCI relative to the NE, but maintained at the same level up to mild AD. EMCI exhibited the same degree of performance with NE for inhibitory control and mental set-shifting; however, they progressively worsened from EMCI to mild AD. CONCLUSIONS: These results suggest that impairments of EF exist even in the earliest stage of the MCI, with a disproportionate decline in the sub-domains of EF.

Disproportionate Decline of Executive Functions in Early Mild Cognitive Impairment, Late Mild Cognitive Impairment, and Mild Alzheimer's Disease

BACKGROUND AND PURPOSE: Many literatures indicate that executive dysfunction exists in mild cognitive impairment (MCI) as well as Alzheimer’s disease (AD). However, there are few studies that found how early the deficits of the executive function (EF) exist in MCI. The present study investigated the presence of executive dysfunctions in the earliest stage of MCI, and the sub-domains of EF which are disproportionately impaired earlier than others. METHODS: The participants were 41 normal elderly (NE), 86 with amnestic multi-domain MCI, and 41 with mild AD. The MCI group was further sub-divided into two groups: Early MCI (EMCI, n=45) and late MCI (n=41), based on the Clinical Dementia Rating-Sum of Boxes. All participants were given neuropsychological tests to assess the sub-domains of EF, such as verbal fluency, psychomotor speed, inhibitory control, and mental set-shifting. RESULTS: Impairment of semantic fluency was observed in EMCI, with gradual worsening as cases approached mild AD. Phonemic fluency and psychomotor speed were also impaired at the early stage of MCI relative to the NE, but maintained at the same level up to mild AD. EMCI exhibited the same degree of performance with NE for inhibitory control and mental set-shifting; however, they progressively worsened from EMCI to mild AD. CONCLUSIONS: These results suggest that impairments of EF exist even in the earliest stage of the MCI, with a disproportionate decline in the sub-domains of EF.