PLEASURE OF LEARNING NEW WORDS
From our very first
years, we are intrinsically motivated to learn new words and their meanings.
First language acquisition occurs within a permanent emotional interaction
between parents and children. However, the exact mechanism behind the human
drive to acquire communicative linguistic skills is yet to be established.
In a study published
in the journal Current Biology, researchers from the University of
Barcelona (UB), the Bellvitge Biomedical Research Institute (IDIBELL) and the
Otto von Guericke University Magdeburg (Germany) have experimentally proved
that human adult word learning exhibit activation not only of cortical language
regions but also of the ventral striatum, a core region of reward processing.
Results confirm that the motivation to learn is preserved throughout the
lifespan, helping adults to acquire a second language.
Researchers determined
that the reward region that is activated is the same that answers to a wide
range of stimuli, including food, sex, drugs or game. "The main objective
of the study was to know to what extent language learning activates subcortical
reward and motivational systems," explains Pablo Ripollés, PhD student at
UB-IDIBELL and first author of the article. "Moreover, the fact that
language could be favoured by this type of circuitries is an interesting
hypothesis from an evolutionary point of view," points out the expert.
According to Antoni
RodrĂguez Fornells, UB lecturer and ICREA researcher at IDIBELL, "the
language region has been traditionally located at an apparently encapsulated
cortical structure which has never been related to reward circuitries, which
are considered much older from an evolutionary perspective." "The
study -- he adds -- questions whether language only comes from cortical
evolution or structured mechanisms and suggests that emotions may influence
language acquisition processes."
Subcortical areas are
closely related to those that help to store information. Therefore, those facts
or pieces of information that awake an emotion are more easily to remember and
learn.
Motivation for
learning a second language
By using diffusion
tensor imaging, UB-IDIBELL researchers reconstructed the white matter pathways
that link brain regions in each participant. Experts were able to correlate the
number of new words learnt by each person during the experiment with a low
myelin index, a measure of structure integrity. Results proved that subjects
who presented higher myelin concentrations in the structures that carry
information to the ventral striatum -- in other words, those that are best
connected to the reward area -- were able to learn more words.
"Results provide
a neural substrate of the influence that reward and motivation circuitries may
have in learning words from context," affirms Josep Marco Pallarès,
UB-IDIBELL researcher. The activation of these circuitries during word learning
suggests future research lines aimed at stimulating reward regions to improve
language learning in patients with linguistic problems.
The fact that
non-linguistic subcortical mechanisms, which are much older from an
evolutionary perspective, work together with language cortical regions -- which
appeared latter -- suggests new language theories trying to explain how reward
mechanisms have influenced and supported one of our primal urges: the desire to
acquire language and to communicate.
Experiment with words
and gambling
Researchers carried
out an experiment with thirty-six adults who participated in two magnetic
resonance sessions. On the first one, functional magnetic resonance was used to
measure participants' brain activity while they perform two different tasks.
This technique enables to detect accurately what brain regions are active while
a person is performing a certain activity. In the first task, participants must
learn the meaning of some new words from context in two different sentences.
For instance, subjects saw on a screen the sentences: "Every Sunday the
grandmother went to the jedin" and "The man was buried in
the jedin." Considering both sentences, participants could
learn that the word jedin means "graveyard." Then,
participants completed two runs of a standard-event-related money gambling
task.
The experiment
revealed that when subjects inferred and memorized the meaning of a new word,
brain activity in the ventral striatum was increased. Indeed, the same ventral
striatum activation was observed when earning money in gambling. Therefore, to
learn the meaning of a new word activates reward and motivational circuitries
like in gambling activities. Moreover, it was observed that word learning
produce an increase of brain activity synchronization between the ventral
striatum and cortical language regions.
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