Babies pick up language at high speed, much faster than adults. They only need a few months to begin to understand basic words and in a year, they themselves begin to articulate words. Scientists have even proposed that the acquisition of language begins before birth because at six or seven months of gestation, the fetus can already hear and newborns prefer their mother’s voice over other female voices. Research published today in the journal Science Advances influences this field and suggests that stimulation with speech in prenatal stages through the mother’s voice already produces changes in the baby’s neural activity that contribute to the learning of newborns in language processing: from before birth , the baby’s brain begins to model itself, from those first experiences with language, to understand its native language.
In the final stages of pregnancy, the fetus can hear sounds from outside, but weakened. The uterus acts as a kind of filter that attenuates frequencies above 600 hertz: individual sounds are suppressed, and only the melody and rhythm of speech are preserved. Enough, in any case, for newborns to prefer their mother’s voice over others and to lean towards the language that the surrogate mother spoke during pregnancy instead of other languages.
What was not known until now is how the brains of children were shaped by those first linguistic experiences and whether, in any case, this prenatal exposure could improve their ability to learn language in the first stages of life. “It was still not clear how much babies learn from prenatal experience,” admits the author of the study, Judit Gervain, a researcher at the Center for Neuroscience at the University of Padua (Italy). “Previous studies, including studies from our lab, have shown that this filtered prenatal experience [por los tejidos maternos] It effectively shapes babies’ ability to perceive speech and shapes brain mechanisms related to language. What is new about our study is that we show learning as it develops. “We discovered that the activity of the newborn’s brain is modified in real time, even several minutes after listening to speech in the native language, that is, the language heard before birth,” explains the author.
The researchers analyzed, through encephalography, the neuronal activity of 33 newborns of French-speaking mothers. They placed caps with a dozen electrodes located near brain areas associated with auditory and speech perception and monitored their activity. “We first measured resting-state activity for three minutes. The babies then listened to speech in three different languages: French, Spanish and English in seven-minute blocks. Finally, resting-state activity was measured again for three minutes,” the authors explain. The speech stimuli were soft recordings, directed at an infant, with phrases translated into the three languages of the story. Goldilocks and the Three Bears.
By comparing resting states with cycles of linguistic stimulation, the researchers wanted to decipher whether exposure to language affects neural dynamics in the infant brain. “Plastic changes immediately after exposure to speech may underlie infants’ ability to learn about the sound patterns they hear. We wonder if exposure to speech produces lasting changes in neuronal dynamics, supporting learning and memory,” justify the authors. Another question to resolve was whether these plastic changes in the brain occur after exposure to all languages or only to the language heard during the prenatal stage. That is, if prenatal experience already shapes, in some way, neural circuits. “If prenatal experience already has an influence, then newborns may show greater plastic changes after exposure to prenatally heard language than after unfamiliar languages,” the researchers consider.
After carrying out the studies, the scientists concluded in their article that “the electrophysiological activity of newborns exhibits long-range temporal correlations [LRTC, por sus siglas en inglés] increased after speech stimulation, particularly in language heard before birth, indicating the early emergence of brain specialization for native language.” LRTCs are a unit of measurement that indicates, according to Gervain, “how similar a signal, in this case that of brain activity, is to itself on large time scales.” “We found that after stimulation with the native language, babies’ brain activity is more similar to their previous states than before stimulation. This is, therefore, a sign of learning,” says the scientist.
So what happens when newborns are exposed to their mother’s language is that the babies’ brain activity becomes organized in such a way that the activity repeats or resembles itself over long periods of time. “We could say that she retains a certain type of memory of her own responses to previous events and those same responses become more frequent,” Gervain translates. The experience of language in prenatal stages can therefore begin to shape the brain and contribute to learning. “The results show that for French, the language heard prenatally, but not for two unfamiliar languages, brain activity shows more “memory” of previous states. This demonstrates the learning of the language heard before birth,” says Gervain.
Non-deterministic impact
What the research does clarify is that, although its findings suggest that the prenatal period lays the foundations for greater language development, “its impact is not deterministic.” “It means that it helps and supports the learning of the same language. However, if the language heard prenatally is not the one the baby will learn after birth, for example, due to adoption or moving, etc., having no prenatal experience does not have a strong detrimental effect. Newborns can learn languages to which they were not exposed prenatally in a typical and normal way,” emphasizes the researcher.
Jordi Costa Faidella, researcher at the Institute of Neurosciences of the University of Barcelona and the Sant Joan de Déu Research Institute, considers that this study “adds evidence to a booming field, such as that which investigates the effects of prenatal exposure to auditory stimulation produced by the mother or environmental sound. The most innovative thing, he indicates, is the applied methodology. “What this study provides is this idea that the learning with which the baby is born is quite specific: the baby’s brain activity is in tune with the mother’s language, the brain rhythms adjust to the mother’s rhythm,” Costa Faidella explains. The scientist highlights that this study, in which he has not participated, opens possibilities for early interventions in babies at risk of having language acquisition problems: “If plastic changes are already generated from the womb due to this exposure, perhaps interventions can be made earlier in babies born at risk for future language-related problems. For example, babies with low birth weight or high birth weight, who may be more likely to suffer some delay in language acquisition,” suggests the researcher.
In practice, in any case, the importance of exposure to language is already recognized as a key element in neurodevelopment. In the neonatology unit of the Vall d’Hebron Hospital in Barcelona, which cares for premature children, they usually use voices as a neurostimulation tool. “Above all, the mother’s voice. We try to stimulate it with her voice when she is in the incubator,” says Fátima Camba, neonatologist in this service. They are aware of the importance of these premature babies, outside the uterus before their time, also being exposed to voice and language: all of this is key to neurodevelopment, the doctor points out. “When the baby is born prematurely, we try to ensure that her development is as close as possible to life inside the womb because we know that the external stimuli she receives are inappropriate for her and can affect her. Thus, when he is born prematurely, we try to simulate the environment of the womb and we look for a silent environment, so that the mother speaks to him in a way similar to what she would hear inside the womb,” she explains.
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