Study finds why adults struggle to learn a new language

The study in patients with epilepsy is helping researchers understand how the brain manages the task of learning a new language while retaining our mother tongue.

Washington: A new study by neuroscientists at UC San Francisco has shed light on the age-old question of why it’s so difficult to learn a second language as an adult.
The findings of the study were published in the journal ‘Proceedings of the National Academy of Sciences’.

The study in patients with epilepsy is helping researchers understand how the brain manages the task of learning a new language while retaining our mother tongue.

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“When learning a new language, our brains are somehow accommodating both of these forces as they’re competing against each other,” said Matt Leonard, PhD, assistant professor of neurological surgery and a member of the UCSF Weill Institute for Neurosciences.
By using electrodes on the surface of the brain to follow high-resolution neural signals, the team found that clusters of neurons scattered throughout the speech cortex appear to fine-tune themselves as a listener gains familiarity with foreign sounds.

The team worked with 10 patient volunteers, aged 19 to 59, whose native language is English, and asked them to recognise speech sounds in Mandarin.
Mandarin is a tonal language in which the meaning of the word relies not only on the vowel and consonant sounds but also on subtle changes in the pitch of the voice, known as tones.
Speakers of non-tonal languages like English often find it very challenging to discern these unfamiliar sounds.
Each of the volunteers had previously had brain surgery, during which electrodes were implanted in their brains to locate the source of their seizures.

Over the course of the next few days, Leonard and Yi worked with the volunteers individually, playing recordings of several native Mandarin speakers of different ages, both male and female, pronouncing syllables like “ma” and “di” using each of the four tones.
After each sound, the patient indicated whether they thought the tone was going up, down, up and then down, or staying flat, and received feedback on whether they were correct. Leonard and Yi think this may explain why some people pick up the sounds much more easily than others, as each unique brain strikes its own balance between maintaining the stability of the native language while calling on the plasticity required to learn a new one.