Scientists using fMRI scans of the entire brain have found that bilinguals have more efficient communication between different brain regions, especially between the cerebellum and the left frontal cortex. Learning a second language, especially in childhood, improves brain connectivity, boosting cognitive flexibility and neuroplasticity. This can lead to better cognitive performance and greater resilience to age-related decline.
Bilingualism offers a unique opportunity to study how the brain organizes and processes language. This is because the human brain has a remarkable ability to adapt and change throughout life, a phenomenon called neuroplasticity.
When we learn something new, especially a new language, the brain changes, both in its structure (physical) and in its functionality (how it processes information).
An important question in neuroscience is how age affects these changes. Learning a language from birth, when the brain is still developing, results in a different brain organization compared to learning a second language in adulthood, when the brain already has established pathways for processing the first language.
Studies show that bilingualism can improve several cognitive functions, such as memory, attention, and even the ability to understand speech in noisy environments. In addition, bilingualism can help protect the brain against aging, brain injuries, or conditions such as epilepsy.
Neuroimaging research (such as fMRI, which studies the brain in action) suggests that learning a second language affects specific areas of the brain, such as the cerebellum and regions of the left hemisphere associated with language processing.
However, bilingualism has also been observed to influence other parts of the brain, including areas involved in cognitive control, which help coordinate the different tasks required for using multiple languages.
Another interesting aspect of bilingualism is that it not only affects specific regions of the brain but also improves the way different areas of the brain communicate with each other.
The brain functions as a complex network of interconnected areas, and the efficiency of this network is crucial for cognition. Research shows that bilinguals tend to have greater functional integration between these brain areas, which means that a bilingual person’s brain is more efficient in its operations.
A new study from McGill University’s Neuro (Montreal Neurological Institute-Hospital), the University of Ottawa, and the University of Zaragoza in Spain elaborates on the role of bilingualism in cognition, showing increased efficiency of communication between brain regions. Scientists recruited 151 participants who spoke French, English, or both languages and recorded the age at which they learned their second language.
The participants were scanned using resting-state functional magnetic resonance imaging (fMRI) to record connectivity across the brain, rather than focusing on specific regions, as has been done in previous studies of bilingualism.
The fMRI scans revealed that bilingual participants had greater connectivity between brain regions than monolingual participants, and this connectivity was stronger in those who learned their second language at a younger age. This effect was particularly strong between the cerebellum and the left frontal cortex.
Whole-brain network analyses reveal greater global efficiency in bilingual individuals than in monolinguals, indicating greater functional integration in the bilingual brain.
The Figure shows brain regions that showed greater cortical and corticocerebellar connectivity in the bilingual group compared to the monolingual group. The frequency bar graph is divided into intra-right (R–R), intra-left (L–L), or inter-hemispheric (L–R) borders. Auditory AUD, cerebellar CBL, cingulo-opercular CON, cingulo-parietal CPN, default mode DMN, dorsal attention DAN, fronto-parietal FPN, retrosplenial-temporal RTN, salience SAL, sensorimotor-hand SMH, sensorimotor-mouth SMM, subcortical SUB, ventral attention VAN, visual VIS.
In addition, the age at which the second language was acquired correlated with this greater efficiency, suggesting that early exposure to a second language has lasting positive effects on the functional organization of the brain.
Further investigation using the network-based statistical approach indicates that this effect is primarily driven by increased functional connectivity between association networks and the cerebellum. These findings show that the timing of the bilingual learning experience alters the functional organization of the brain at both global and local levels.
Figure 1 shows that cortical and corticocerebellar connectivity was greater in early simultaneous bilinguals compared to monolinguals. Auditory AUD, cerebellar CBL, cingulo-opercular CON, cingulo-parietal CPN, default mode DMN, dorsal attention DAN, fronto-parietal FPN, retrosplenial-temporal RTN, salience SAL, sensorimotor-hand SMH, sensorimotor-mouth SMM, subcortical SUB, ventral attention VAN, visual VIS.
In summary, bilingualism not only improves cognitive abilities but also reorganizes the brain in ways that go beyond simple language processing. The age at which a person learns a second language has a significant impact on the efficiency and organization of this brain network, with cognitive advantages that can last a lifetime.
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Enhanced efficiency in the bilingual brain through the inter-hemispheric cortico-cerebellar pathway in early second language acquisition
Gracia-Tabuenca, Z., Barbeau, E.B., Kousaie, S. et al.
Commun Biol 7, 1298 (2024). doi.org/10.1038/s42003-024-06965-1
Abstract:
Bilingualism has a profound impact on the structure and function of the brain, but it is not yet well understood how this experience influences brain functional organization. We examine a large sample (151 participants) of monolinguals and bilinguals with varied ages of second language acquisition, who underwent resting-state functional magnetic brain imaging. Whole-brain network analyses reveal higher global efficiency in bilingual individuals than in monolinguals, indicating enhanced functional integration in the bilingual brain. Moreover, the age at which the second language was acquired correlated with this increased efficiency, suggesting that earlier exposure to a second language has lasting positive effects on brain functional organization. Further investigation using the network-based statistics approach indicates that this effect is primarily driven by heightened functional connectivity between association networks and the cerebellum. These findings show that the timing of bilingual learning experience alters the brain's functional organization at both global and local levels.
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