Why can one adult learn a new word almost effortlessly while another struggles? This study suggests the answer may partly lie in how two distant parts of the resting brain keep time together. For some people, learning a foreign language is time-consuming and challenging, while for others, high levels of language proficiency can be attained with relative ease and little time investment.

Foreign language acquisition, especially in adulthood, is characterized by considerable variability in the learning rate and ultimate attainment. It is largely unknown whether differences in word learning ability may depend in part on differences in spontaneous brain connectome patterns at rest.

The study investigated whether brain connections measured before a task were related to adults’ ability to acquire novel words. The expectation was that resting communication between the back and front of the brain could predict differences in word learning ability. The functional connection between distinct brain regions was estimated by comparing whether their electrical signals moved together.

The study examined connections across several broad rhythms of brain activity, including the rhythm called alpha, which is between eight and twelve cycles per second. People who learned more new words tended to have more closely synchronized resting brain signals between the back and front of the brain.

This pattern appeared across several connections, linking the brain’s background communication to later learning ability. Resting communication between the back and front of the brain significantly correlated with differences in word learning performance.

Connectivity strength in the high-performance group was significantly stronger than in the low-performance group. People who learned more new words tended to have stronger resting coordination between the brain’s visual and frontal regions. The same relationship appeared in a separate group, suggesting this quiet brain signal may help identify word-learning ability.

The main findings were replicated in an independent validation study: resting communication between the back and front of the brain significantly correlated with word learning performance. The findings cannot yet show whether stronger brain communication causes better learning, because the research measured the relationship at one point in time.

The study also used invented English-like words, so it remains unclear whether the findings generalize to learning real words in a new language. Resting communication between the back and front of the brain predicted differences in word learning performance in adult learners.

These findings suggest that resting brain connections may be a reliable marker of individual learning ability during new language acquisition. The findings may have important implications for the diagnosis and intervention of individuals with word learning deficits.

Adults who learned new words more successfully had stronger resting communication between the back and front of the brain before learning began. That signal might eventually help identify who needs extra support, though it cannot yet prove or change ability.