July 1, 2011

Babies More Attuned To Our Voices And Emotions Than Toys

Human voices and emotions showed more activation in a part of young babies' brains than familiar sounds of toys or water, a study published on June 30 in Current Biology found.

Three-to-seven-month-old babies' area of the temporal lobe, known in adults for its role in processing human vocalization, light up more at human sounds such as coughing, sneezing or yawning. In addition, the babies responded more to sad sounds than to neutral sounds in another part of the brain that handles emotion processing, the study says.

"Our results suggest that the infant temporal cortex is more mature than previously reported," Evelyne Mercure of University College London says. "It is a rare demonstration that specialized areas exist in the brain very early in development."

Anna Blasi of King's College London suggests that, "It is probably because the human voice is such an important social cue that the brain shows an early specialization for its processing."

"This may represent the very first step in social interactions and language learning."

Earlier evidence that infants can extract subtle information from human speech is consistent with the findings in the new study.

For example, newborns are able to detect their mother's voice and their mother tongue, the report cites. In addition, differentiation between voices of men and women as well as children and adults can be perceived by infants.

Functional magnetic resonance imaging (FMRI) was used by the researchers in the new study to record sleeping babies' responses, while they were sleeping, to emotionally neutral, positive, or negative human vocalizations or non-vocal environmental sounds.

Mercure says, "We were very surprised to find that the area of the temporal cortex that responded to the human voice more than to environmental sounds was so similar in its location to the adult area showing the same specialization."

Infant fMRI is not an exact science, she says, making the results even more reassuring and surprising because they were so similar to the adult literature.

"We are now carrying out more research in this area to help us understand how differences in brain development arise, if we can use these to accurately identify babies who will go on to suffer from disorders such as autism, and if they can be used to help measure the effectiveness of interventions," the study's author Declan Murphy of King's College London adds.


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