"Hot" executive functions are comparable across monolingual and bilingual elementary school children: Results from a study with the Iowa Gambling Task.

Past research found performance differences between monolingual and bilingual children in the domain of executive functions (EF). Furthermore, recent studies have reported advantages in processing efficiency or mental effort in bilingual adults and children. These studies mostly focused on the investigation of "cold" EF tasks. Studies including measures of "hot" EF, i.e., tasks operating in an emotionally significant setting, are limited and hence results are inconclusive. In the present study, we extend previous research by investigating performance in a task of the "hot" EF domain by both behavioral data and mental effort via pupillary changes during task performance. Seventy-three monolingual and bilingual school children (mean age = 107.23 months, SD = 10.26) solved the Iowa Gambling Task in two different conditions. In the standard task, characterized by constant gains and occasional losses, children did not learn to improve their decision-making behavior. In a reversed task version, characterized by constant losses and occasional gains, both monolinguals and bilinguals learned to improve their decision-making behavior over the course of the task. In both versions of the task, children switched choices more often after losses than after gains. Bilinguals switched their choices less often than monolinguals in the reversed task, indicating a slightly more mature decision-making strategy. Mental effort did not differ between monolinguals and bilinguals. Conclusions of these findings for the bilingual advantage assumption will be discussed.

Executive functions in mono- and bilingual children: Factor structure and relations with fluid intelligence.

The effects of bilingualism on executive functions (EFs) and intelligence are still controversially discussed. Most studies have focused on performance differences without considering the underlying structure of cognitive abilities. Thus, we examined whether the structure of EFs and the relations of EFs with intelligence differ between mono- and bilingual children. A total of 240 elementary school children (mean age = 8 years 6 months; 133 monolinguals and 95 bilinguals) performed two tasks measuring working memory, inhibition, cognitive flexibility, and fluid intelligence, respectively. Confirmatory factor analyses showed that one common EF factor provided the best fit to the data in both language groups, indicating that bilingualism is not associated with differences in the EF structure at this age. Moreover, there were no latent performance differences in either EFs or intelligence between mono- and bilingual children. However, we found a stronger relation between a common EF factor and fluid intelligence in bilingual children as compared with monolingual children, implying a closer coupling of EFs and intelligence abilities in bilingual children. This contributes to explaining the previous heterogeneous findings on the task level because more closely coupled cognitive functioning can be slightly beneficial for some tasks and irrelevant or even slightly obstructive for others.

Age-differences in network models of self-regulation and executive control functions.

Self-regulation (SR) and executive control functions (EF) are broad theoretical concepts that subsume various cognitive abilities supporting the regulation of behavior, thoughts, and emotions. However, many of these concepts stem from different psychological disciplines relying on distinct methodologies, such as self-reports (common in SR research) and performance-based tasks (common in EF research). Despite the striking overlap between SR and EF on the theoretical level, recent evidence suggests that correlations between self-report measures and behavioral tasks can be difficult to observe. In our study, participants from a life-span sample (14-82 years) completed self-report measures and behavioral tasks, which were selected to include a variety of different facets of SR (e.g., sensation seeking, mindfulness, grit, or eating behavior) and EF (working memory, inhibition, shifting). Using this broad approach, we systematically investigated connections and overlap of different aspects of SR and EF to improve their conceptual understanding. By comparing network models of a youth, middle-aged, and older-aged group, we identified key variables that are well connected in the SR and EF construct space. In general, we found connections to be stronger within the clusters of SR and EF than between them. However, older adults demonstrated more connections between SR and EF than younger individuals, likely because of declining cognitive resources.

The relations between personality, components of executive functions, and intelligence in children and young adults.

Previous studies in adults showed heterogeneous results regarding the associations of personality with intelligence and executive functions (EF). In children, there is a lack of studies investigating the relations between personality and EF. Therefore, the aim of our study was to examine the relations between the Big Five personality traits, EF, and intelligence in a sample of children (Experiment 1) and young adults (Experiment 2). A total of 155 children (Experiment 1, mean age = 9.54 years) and 91 young adults (Experiment 2, mean age = 23.49 years) participated in the two studies. In both studies, participants performed tasks measuring working memory (WM), inhibitory control, cognitive flexibility, and fluid intelligence and completed a personality questionnaire. In Experiment 1, we found a negative relation between neuroticism and intelligence. In Experiment 2, we found a positive relation between conscientiousness and intelligence and a positive relation between conscientiousness and cognitive flexibility. Our results suggest a complex interplay between personality factors, EF, and intelligence both in children as well as in young adults.

[Formula: see text] The unique contribution of working memory, inhibition, cognitive flexibility, and intelligence to reading comprehension and reading speed.

There are several studies showing that executive functions such as working memory, inhibition, and cognitive flexibility are related to reading abilities. However, most of these studies did not simultaneously take different executive functions and intelligence into account. Therefore, the aim of our study was to investigate if working memory, inhibition, cognitive flexibility, and fluid intelligence uniquely contribute to reading. Furthermore, we tested the hypothesis that reading comprehension and reading speed are correlated but separable reading abilities with different relations to other cognitive functions. To test this assumption, we examined if executive functions and fluid intelligence unequally relate to reading comprehension and reading speed. A total of 186 school children (mean age = 9.31 years) participated in our study and performed a complex span task (working memory), task switching (cognitive flexibility), a stroop-like task (inhibition), raven matrices (fluid intelligence), a reading speed task and three reading comprehension tasks. Structural equation modeling (SEM) showed that working memory, inhibition, cognitive flexibility and fluid intelligence differently contributed to reading speed and reading comprehension. Working memory, inhibition and fluid intelligence were related to reading speed, indicating that a higher working memory capacity, better inhibitory abilities and higher fluid intelligence were associated with higher reading speed. Moreover, cognitive flexibility and fluid intelligence were related to reading comprehension, suggesting that higher cognitive flexibility and fluid intelligence were associated with better reading comprehension. Thus, our results point to differential contributions of executive functions to reading comprehension and reading speed.

Effects of game-based and standard executive control training on cognitive and academic abilities in elementary school children.

Several studies indicate that executive functions (EF), such as working memory (WM), inhibition or flexibility can be improved by training and that these training-related benefits in WM capacity generalize to reading and mathematical abilities. However, the results of these studies are inconsistent and most of them focused on WM training in children with learning difficulties. Evidence for typically developing children is rare and no study has investigated inhibition training or flexibility training. There is also a lack of studies taking motivational factors into account. Therefore, this study compared the effects of game-based and standard training regimens targeting WM, inhibition, or flexibility in children. One hundred and fifty-three typically developing elementary school students (mean age = 9.6 years, standard deviations  = 0.8) were investigated in an intervention design with a pretest, 21 sessions of training, a posttest and a follow-up after three months. They were randomized into one of six training groups or a control group. We found training gains in all training groups and higher self-reported motivation in the game-based as compared to the standard training groups. Furthermore, there was domain-specific transfer to untrained EF tasks across all training groups. We found greater performance improvements in reading ability (but not mathematics) in the game-based flexibility training group and the game-based inhibition training group as compared to the control group. Transfer effects were still significant at follow-up. In sum, our findings provide first evidence for a systematic comparison of training on different domains of EF and their differential effects on academic abilities.

Validation of new online game-based executive function tasks for children.

Numerous tasks are available to measure executive functions (EFs; working memory, inhibition, and flexibility) in children. However, they differ massively in the way they are presented and framed. Some contain child-friendly stimuli, feedback, or game elements likely to increase motivation and interest to perform the tasks, whereas others do not. Yet, it is unclear whether these apparent differences affect task performance. Therefore, the aim of our study was to develop and validate new game-based tasks assessing EFs in children. We designed three tasks for each dimension of EF and implemented them in a game version (based on the motivational framework proposed by Ryan and Deci (2000) and a standard version. The game-based tasks included elements designed to improve perceived competence (appealing feedback), autonomy (choosing how the protagonists proceed), and relatedness (a child-friendly cover story). To investigate whether adding these game elements influenced the motivation to engage in these tasks and task performance, 60 children (third and fourth graders) performed the game-based version and the standard version in two sessions (counterbalanced across participants). Because both the game-based and standard versions of the tasks should tap the same cognitive processes, we also tested whether performances in both versions were correlated. We found higher self-reported motivation in terms of interest, perceived competence, and relatedness after performing the game-based version as compared with the standard version. Performance on the game-based and standard versions of most of the tasks was significantly correlated, and there were no performance differences between the game-based and standard versions.

Time of transplantation and cell preparation determine neural stem cell survival in a mouse model of Huntington's disease.

Cell replacement therapies for neurodegenerative diseases, using multipotent neural stem cells (NSCs), require above all, a good survival of the graft. In this study, we unilaterally injected quinolinic acid (QA) into the striatum of adult mice and transplanted syngeneic NSCs of enhanced green fluorescent protein-transgenic mice into the lesioned striatum. The injection of QA leads to an excitotoxic lesion with selective cell death of the medium sized spiny neurons, the same cells that are affected in Huntington's disease. In order to investigate the best timing of transplantation for the survival of donor cells, we transplanted the stem cells at 2, 7 and 14 days after injury. In addition, the influence of graft preparation prior to transplantation, i.e., intact neurospheres versus dissociated cell suspension on graft survival was investigated. By far the best survival was found with the combination of early transplantation (i.e., 2 days after QA-lesion) with the use of neurospheres instead of dissociated cell suspension. This might be due to the different states of host's astrocytic and microglia activation which we found to be moderate at 2, but pronounced at 7 and 14 days after QA-lesion. We also investigated brain derived neurotrophic factor (BDNF)-expression in the striatum after QA-lesion and found no significant change in BDNF protein-level. We conclude that already the method of graft preparation of NSCs for transplantation, as well as the timing of the transplantation procedure strongly affects the survival of the donor cells when grafted into the QA-lesioned striatum of adult mice.

Neural cell adhesion molecule L1-transfected embryonic stem cells promote functional recovery after excitotoxic lesion of the mouse striatum.

We have generated a murine embryonic stem cell line constitutively expressing L1 at all stages of neural differentiation to investigate the effects of L1 overexpression on stem cell proliferation, migration, differentiation, cell death, and ability to influence drug-induced rotation behavior in an animal model of Huntington's disease. L1-transfected cells showed decreased cell proliferation in vitro, enhanced neuronal differentiation in vitro and in vivo, and decreased astrocytic differentiation in vivo without influencing cell death compared with nontransfected cells. L1 overexpression also resulted in an increased yield of GABAergic neurons and enhanced migration of embryonic stem cell-derived neural precursor cells into the lesioned striatum. Mice grafted with L1-transfected cells showed recovery in rotation behavior 1 and 4 weeks, but not 8 weeks, after transplantation compared with mice that had received nontransfected cells, thus demonstrating for the first time that a recognition molecule is capable of improving functional recovery during the initial phase in a syngeneic transplantation paradigm.

The metabotropic glutamate receptor 5 antagonist MPEP and the mGluR2 agonist LY379268 modify disease progression in a transgenic mouse model of Huntington's disease.

Chronic glutamate mediated excitotoxicity has been suggested to contribute to the pathogenesis of Huntington's disease (HD). Both, inhibition of glutamate release through stimulation of presynaptic metabotropic glutamate receptor (mGluR) 2 and blockade of postsynaptic mGluR5 have been demonstrated to be neuroprotective against excitotoxicity. R6/2 HD transgenic mice which express an expanded CAG triplet repeat serve as a well-characterized mouse model for HD with progressing neurological abnormalities and limited survival. We treated R6/2 HD transgenic mice with either the mGluR2 agonist LY379268 (1.2 mg/kg) or with the mGluR5 antagonist 2-methyl-6-(phenylethynyl)-pyridine (MPEP) (100 mg/kg) orally from a presymptomatic stage until death to investigate their potential disease modifying effects. We found that survival time in both the MPEP treated mice and the LY379268 treated mice was significantly increased in comparison to placebo treated transgenic controls (14.87+/-0.14 and 14.22+/-0.11 weeks versus 12.87+/-0.11 weeks, respectively). Additionally, the progressive decline in motor coordination of HD transgenic mice as tested with the rotarod test was significantly attenuated in MPEP- but not in LY379268-treated mice. Early pathological hyperactivity, which can be found in placebo treated HD transgenic mice, was significantly attenuated by both MPEP and LY379268 treatment. Immunohistologial examination of HD characteristic neuronal intranuclear inclusion (NII), however, demonstrated no effect on NII formation by either of the treatments applied. These data suggest that inhibition of glutamate neurotransmission via specific interaction with mGluRs might be interesting for both inhibition of disease progression as well as early symptomatic treatment in HD.

Retinoic acid downregulates the expression of ciliary neurotrophic factor in rat Schwann cells.

Neuropoietic cytokines, which serve as mediators in neuroglial interactions, are differentially regulated after peripheral nerve injury. In Schwann cells, the expression of ciliary neurotrophic factor (CNTF) decreases. Pursuing the hypothesis that retinoic acid (RA) serves as a regulator of lesion-induced cytokine signaling we found that all RA receptors and retinoid X receptors are expressed in Schwann cell primary cultures. Using quantitative reverse transcription-polymerase chain reaction, we have investigated the effect of RA on the expression of CNTF in these cells. After treatment with 10 nM all-trans RA for 22 h the concentration of CNTF mRNA was reduced to 63% of the control level, reminiscent of the regulation after nerve injury in vivo. In addition to CNTF, the mRNAs of leukemia inhibitory factor, interleukin-6, ciliary neurotrophic factor receptor component alpha and gp130 were detected in the Schwann cells.