Inhibitory control training reveals a common neurofunctional basis for generic executive functions and language switching in bilinguals

Does music training improve inhibition control in children? A systematic review and meta-analysis

Inhibition control is an essential executive function during children's development, underpinning self-regulation and the acquisition of social and language abilities. This executive function is intensely engaged in music training while learning an instrument, a complex multisensory task requiring monitoring motor performance and auditory stream prioritization. This novel meta-analysis examined music-based training on inhibition control in children. Records from 1980 to 2023 yielded 22 longitudinal studies with controls (N = 1734), including 8 RCTs and 14 others. A random-effects meta-analysis showed that music training improved inhibition control (moderate-to-large effect size) in the RCTs and the superset of twenty-two longitudinal studies (small-to-moderate effect size). Music training plays a privileged role compared to other activities (sports, visual arts, drama) in improving children's executive functioning, with a particular effect on inhibition control. We recommend music training for complementing education and as a clinical tool focusing on inhibition control remediation (e.g., in autism and ADHD).

iTBS reveals the roles of domain-general cognitive control and language-specific brain regions during word formation rule learning

Repeated exposure to word forms and meanings improves lexical knowledge acquisition. However, the roles of domain-general and language-specific brain regions during this process remain unclear. To investigate this, we applied intermittent theta burst stimulation over the domain-general (group left dorsolateral prefrontal cortex) and domain-specific (Group L IFG) brain regions, with a control group receiving sham intermittent theta burst stimulation. Intermittent theta burst stimulation effects were subsequently assessed in functional magnetic resonance imaging using an artificial word learning task which consisted of 3 learning phases. A generalized psychophysiological interaction analysis explored the whole brain functional connectivity, while dynamic causal modeling estimated causal interactions in specific brain regions modulated by intermittent theta burst stimulation during repeated exposure. Compared to sham stimulation, active intermittent theta burst stimulation improved word learning performance and reduced activation of the left insula in learning phase 2. Active intermittent theta burst stimulation over the domain-general region increased whole-brain functional connectivity and modulated effective connectivity between brain regions during repeated exposure. This effect was not observed when active intermittent theta burst stimulation was applied to the language-specific region. These findings suggest that the domain-general region plays a crucial role in word formation rule learning, with intermittent theta burst stimulation enhancing whole-brain connectivity and facilitating efficient information exchange between key brain regions during new word learning.

Cognitive and neural mechanisms of voluntary versus forced language switching in Chinese-English bilinguals: an fMRI study

The ecological validity of bilingual code-switching has garnered increasing attention in recent years. Contrary to traditional studies that have focused on forced language switching, emerging theories posit that voluntary switching may not incur such a cost. To test these claims and understand differences between forced and voluntary switching, the present study conducted a systematic comparison through both behavioral and neural perspectives. Utilizing fMRI alongside picture-naming tasks, our findings diverge from prior work. Voluntary language switching not only demonstrated switching costs at the behavioral level but also significantly activated brain regions associated with inhibitory control. Direct comparisons of voluntary and forced language switching revealed no significant behavioral differences in switching costs, and both shared several common brain regions that were activated. On the other hand, a nuanced difference between the two types of language switching was revealed by whole-brain analysis: voluntary switching engaged fewer language control regions than forced switching. These findings offer a comprehensive view of the neural and behavioral dynamics involved in bilingual language switching, challenging prior claims that voluntary switching imposes no behavioral or neural costs, and thus providing behavioral and neuroimaging evidence for the involvement of inhibitory control in voluntary language switching.

Inhibitory control of the dominant language: Reversed language dominance is the tip of the iceberg

Theories of speech production have proposed that in contexts where multiple languages are produced, bilinguals inhibit the dominant language with the goal of making both languages equally accessible. This process often overshoots this goal, leading to a surprising pattern: better performance in the nondominant vs. dominant language, or reversed language dominance effects. However, the reliability of this effect in single word production studies with cued language switches has been challenged by a recent meta-analysis. Correcting for errors in this analysis, we find that dominance effects are reliably reduced and reversed during language mixing. Reversed dominance has also consistently been reported in the production of connected speech elicited by reading aloud of mixed language paragraphs. When switching, bilinguals produced translation-equivalent intrusion errors (e.g., saying pero instead of but) more often when intending to produce words in the dominant language. We show this dominant language vulnerability is not exclusive to switching out of the nondominant language and extends to non-switch words, linking connected speech results to patterns first reported in single word studies. Reversed language dominance is a robust phenomenon that reflects the tip of the iceberg of inhibitory control of the dominant language in bilingual language production.

Executive Functions and Foreign Language Learning

Executive functions (EFs) serve as an umbrella term to describe a set of higher-order cognitive abilities that include working memory, inhibitory control, cognitive flexibility, planning, reasoning, and problem-solving. Various studies suggest that foreign language learning likely promotes executive functions, but others suggest that executive functions could improve foreign language learning. The aim of this study is to investigate the relationship between executive functions and foreign language learning and how these processes could interact. The sample included 64 children from kindergarten, aged 4-5 years, with no documented neuropsychiatric disorders, and from the middle-high literacy group. They were divided into three groups based on the level of their knowledge of the foreign language. A significant effect of the group on the executive tasks is shown in the comparison of the groups. Children who belonged to a group that had advanced foreign language proficiency had better results in executive tasks. Our results suggest that the higher the level of foreign language proficiency, the higher the performance of the executive tasks. However, we do not know if there is a causal effect between these variables.