Learning your first language is easy; it’s the second or even third that can be hard. But learning a second language comes easier to some than others, and a new study suggests this may not have as much to do with studying hard as we may think. According to the study, genetic variations can account for changes in the amount of white matter activity in the brain, which in turn can affect the ease with which you learn a second language.

To test the biological reasoning behind differences in our ability to learn a new language, lead researcher Dr. Ping Mamiya from the University of Washington and his team recruited 44 first-year college students who had just arrived from China and who were involved in a three-week English language immersion class. Following the three-week program, the researchers performed brain scans using an MRI technique called diffusion tensor imaging (DT) on all of the students, including a control group of individuals that had also just arrived from China but who did not take part in the language immersion course. The team was particularly looking for changes in our white brain matter, an area of the brain associated with connecting other areas of the brain.

The DT scans work by giving clearer images microstructures in the brain so that researchers can better understand brain connectivity. Research has suggested that stronger connections between areas of the brain may aid more effective transfer of information throughout the brain and, therefore, enable people to more easily learn new skills. For example, one previous study suggested that some of the developmental delays found in people with autism may be due to abnormalities in white matter.

Results showed clear differences between students who attended the course and those who did not. For example, foreign language exposure increased the connectivity of the brain’s language circuitry, which is located in the white matter, in the enrolled students, compared to no changes in the control group.

However, what was perhaps most interesting was that the students' genetics seemed to control just how much their white brain matter changed during the language course, and in turn how well they learned the language. The researchers took DNA samples of the students at the beginning of the language course and noted that two specific variations of a gene known as the COMT gene were linked to greater increases in brain connectivity in the students who took the language courses. The researchers concluded that having this gene and the changes in white matter it induced accounted for 46 percent of the total variance in the students’ final scores.

The findings add further proof that some people are predisposed to certain skills and abilities and suggest that environment and upbringing are not the only factors that can contribute to whether someone will be successful when attempting to learn a language or another skill.

"Humans' abilities in learning any particular skill vary tremendously, and we want to know why," said co-author Patricia Kuhl, in a recent statement. "Knowing why answers a basic science question about how the environment, our genes, and our brains really work, but could also lead to interventions that improve learning."

Source: Mamiya PC, Richards TL, Coe BP, Eichler EE, Kuhl PK. Brain white matter structure and COMT gene are linked to second-language learning in adults. PNAS. 2016