Non-invasive nerve stimulation boosts learning of foreign language
sounds

Date:
August 6, 2020
Source:
University of Pittsburgh
Summary:
New research by neuroscientists revealed that a simple,
earbud-like device that imperceptibly stimulates the brain could
significantly improve the wearer's ability to learn the sounds
of a new language. This device may have wide-ranging applications
for boosting other kinds of learning as well.



FULL STORY ==========================================================================
New research by neuroscientists at the University of Pittsburgh and
University of California San Francisco (UCSF) revealed that a simple, earbud-like device developed at UCSF that imperceptibly stimulates a
key nerve leading to the brain could significantly improve the wearer's
ability to learn the sounds of a new language. This device may have wide-ranging applications for boosting other kinds of learning as well.


========================================================================== Mandarin Chinese is considered one of the hardest languages for native
English speakers to learn, in part because the language -- like many
others around the world -- uses distinctive changes in pitch, called
"tones," to change the meaning of words that otherwise sound the
same. In the new study, published today in npj Science of Learning (a
Nature partner journal), researchers significantly improved the ability
of native English speakers to distinguish between Mandarin tones by
using precisely timed, non-invasive stimulation of the vagus nerve --
the longest of the 12 cranial nerves that connect the brain to the
rest of the body. What's more, vagus nerve stimulation allowed research participants to pick up some Mandarin tones twice as quickly.

"Showing that non-invasive peripheral nerve stimulation can make language learning easier potentially opens the door to improving cognitive
performance across a wide range of domains," said lead author Fernando
Llanos, Ph.D., a postdoctoral researcher in Pitt's Sound Brain Lab.

"This is one of the first demonstrations that non-invasive vagus
nerve stimulation can enhance a complex cognitive skill like language
learning in healthy people," said Matthew Leonard, Ph.D., an assistant professor, Department of Neurological Surgery, UCSF Weill Institute for Neurosciences, whose team developed the nerve stimulation device. Leonard
is a senior author of the new study, alongside Bharath Chandrasekaran,
Ph.D., professor and vice chair of research, Department of Communication Science and Disorders, Pitt School of Health and Rehabilitation Sciences,
and director of the Sound Brain Lab.

Researchers used a non-invasive technique called transcutaneous vagus
nerve stimulation (tVNS), in which a small stimulator is placed in the
outer ear and can activate the vagus nerve using unnoticeable electrical
pulses to stimulate one of the nerve's nearby branches.

For their study, the researchers recruited 36 native English-speaking
adults and trained them to identify the four tones of Mandarin Chinese
in examples of natural speech, using a set of tasks developed in the
Sound Brain Lab to study the neurobiology of language learning.



========================================================================== Participants who received imperceptible tVNS paired with two Mandarin
tones that are typically easier for English speakers to tell apart
showed quick improvements in learning to distinguish these tones. By the
end of the training, those participants were 13% better on average at classifying tones and reached peak performance twice as quickly as control participants who wore the tVNS device but never received stimulation.

"There's a general feeling that people can't learn the sound patterns
of a new language in adulthood, but our work historically has shown
that's not true for everyone," Chandrasekaran said. "In this study,
we are seeing that tVNS reduces those individual differences more than
any other intervention I've seen." "This approach may be leveling the
playing field of natural variability in language learning ability,"
added Leonard. "In general, people tend to get discouraged by how hard
language learning can be, but if you could give someone 13% to 15%
better results after their first session, maybe they'd be more likely
to want to continue." The researchers now are testing whether longer
training sessions with tVNS can impact participants' ability to learn
to discriminate two tones that are harder for English speakers to differentiate, which was not significantly improved in the current study.

Stimulation of the vagus nerve has been used to treat epilepsy for
decades and has recently been linked to benefits for a wide range of
issues ranging from depression to inflammatory disease, though exactly
how these benefits are conferred remains unclear. But most of these
findings have used invasive forms of stimulation involving an impulse
generator implanted in the chest. By contrast, the ability to evoke
significant boosts to learning using simple, non-invasive vagus nerve stimulation could lead to significantly cheaper and safer clinical and commercial applications.

The researchers suspect tVNS boosts learning by broadly enhancing neurotransmitter signaling across wide swaths of the brain to temporarily
boost attention to the auditory stimulus being presented and promote
long-term learning, though more research is needed to verify this
mechanism.

"We're showing robust learning effects in a completely non-invasive and
safe way, which potentially makes the technology scalable to a broader
array of consumer and medical applications, such as rehabilitation
after stroke," Chandrasekaran said. "Our next step is to understand the underlying neural mechanism and establish the ideal set of stimulation parameters that could maximize brain plasticity. We view tVNS as a potent
tool that could enhance rehabilitation in individuals with brain damage."

========================================================================== Story Source: Materials provided by University_of_Pittsburgh. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Fernando Llanos, Jacie R. McHaney, William L. Schuerman, Han G. Yi,
Matthew K. Leonard, Bharath Chandrasekaran. Non-invasive
peripheral nerve stimulation selectively enhances speech category
learning in adults. npj Science of Learning, 2020; 5 (1) DOI:
10.1038/s41539-020-0070-0 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/08/200806092437.htm

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