Mapping individual aspects of bilingual experience to adaptations in brain structure.

Individual differences in using multiple languages are thought to differentially affect brain structure and function. The present study assessed the neuroanatomical predictions of an emerging theory, the Unifying the Bilingual Experience Trajectories framework, which provides the most comprehensive set of predictions of how individual differences in bilingual experiences lead to specific neural and cognitive adaptations. A total of 140 young adults with variable language experiences were scanned using magnetic resonance imaging and completed demographic questionnaires. Brain structure measures implicated in predictions of the Unifying the Bilingual Experience Trajectories model were extracted and regressed against the model's experiential factors. Consistent with the model's predictions, greater intensity and diversity of bilingual language use resulted in changes in gray matter volume in cortical regions involved in executive control (including inferior frontal gyrus, middle temporal gyrus, angular gyrus, and medial frontal gyrus), indicating adaptations toward handling increased executive control demands. Conversely, duration of bilingual engagement resulted in changes within white matter microstructure (bilateral superior longitudinal fasciculus) and increases in subcortical gray matter (left caudate), indicative of adaptations toward increased efficiency of control. Overall, this research enhances our understanding of how bilingual experiences influence brain structure and provides the first direct empirical evidence for the predictions made by the Unifying the Bilingual Experience Trajectories framework.

Sources of Cognitive Conflict and Their Relevance to Theory-of-Mind Proficiency in Healthy Aging: A Preregistered Study.

Age-related decline in theory of mind (ToM) may be due to waning executive control, which is necessary for resolving conflict when reasoning about other individuals' mental states. We assessed how older (n = 50) and younger (n = 50) adults were affected by three theoretically relevant sources of conflict within ToM: competing self-other perspectives, competing cued locations, and outcome knowledge. We examined which best accounted for age-related difficulty with ToM. Our data show unexpected similarity between age groups when people are representing a belief incongruent with their own. Individual differences in attention and response speed best explained the degree of conflict experienced through incompatible self-other perspectives. However, older adults were disproportionately affected by managing conflict between cued locations. Age and spatial working memory were most relevant for predicting the magnitude of conflict elicited by conflicting cued locations. We suggest that previous studies may have underestimated older adults' ToM proficiency by including unnecessary conflict in ToM tasks.

It is not all about you: Communicative cooperation is determined by your partner's theory of mind abilities as well as your own.

We investigated the relationship between Theory of Mind (ToM) and communicative cooperation. Specifically, we examined whether communicative cooperation is affected by the ToM ability of one's cooperative partner as well as their own. ToM is the attribution of mental states to oneself and others; cooperation is the joint action that leads to achieving a shared goal. We measured cooperation using a novel communicative cooperation game completed by participants in pairs. ToM was measured via the Movies for Assessment of Social Cognition (MASC) task and fluid intelligence via the Raven task. Findings of 350 adults show that ToM scores of both players were predictors of cooperative failure, whereas Raven scores were not. Furthermore, participants were split into low- and high-ToM groups through a median split of the MASC scores: high-ToM individuals committed significantly fewer cooperative errors compared to their low-ToM counterparts. Therefore, we found a direct relationship between ToM and cooperation. Interestingly, we also examined how ToM scores of paired participants determine cooperation. We found that pairs with two high-ToM individuals committed significantly fewer errors compared to pairs with two low-ToM individuals. We speculate that reduced cooperation in low-low ToM pairs is a result of less efficient development of conceptual alignment and recovery from misalignment, compared to high-high ToM dyads. For the first time, we thus demonstrate that it is not all about you; both cooperative partners make key, independent, contributions to cooperative outcomes. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Determinants of cerebral blood flow and arterial transit time in healthy older adults.

Cerebral blood flow (CBF) and arterial transit time (ATT), markers of brain vascular health, worsen with age. The primary aim of this cross-sectional study was to identify modifiable determinants of CBF and ATT in healthy older adults (n = 78, aged 60-81 years). Associations between cardiorespiratory fitness and CBF or ATT were of particular interest because the impact of cardiorespiratory fitness is not clear within existing literature. Secondly, this study assessed whether CBF or ATT relate to cognitive function in older adults. Multiple post-labelling delay pseudo-continuous arterial spin labelling estimated resting CBF and ATT in grey matter. Results from multiple linear regressions found higher BMI was associated with lower global CBF (ß = -0.35, P = 0.008) and a longer global ATT (ß = 0.30, P = 0.017), global ATT lengthened with increasing age (ß = 0.43, P = 0.004), and higher cardiorespiratory fitness was associated with longer ATT in parietal (ß = 0.44, P = 0.004) and occipital (ß = 0.45, P = 0.003) regions. Global or regional CBF or ATT were not associated with processing speed, working memory, or attention. In conclusion, preventing excessive weight gain may help attenuate age-related declines in brain vascular health. ATT may be more sensitive to age-related decline than CBF, and therefore useful for early detection and management of cerebrovascular impairment. Finally, cardiorespiratory fitness appears to have little effect on CBF but may induce longer ATT in specific regions.