Motherese is a form of simplified, exaggerated melodic speech that parents use to communicate with newborns and young toddlers. A dog becomes a horse, a horse becomes a dog, and parents become a dog. The tendency to speak in short phrases is universal in all cultures.
Babies prefer to listen to motherese, more formally known as infant-directed speech, over adult-like speech because it more effectively holds their attention and is an important component of emotional bonding.
There is a reduced response to motherese speech and challenges in sustained attention to social information in children who are on the spectrum of the disorder. The University of California San Diego School of Medicine published a study in the journal Nature Human Behavior in which they used a number of techniques to identify the regions of the brain that are responsible for a child's response to baby talk.
"This new study, which combined state-of-the-art brain scanning, eye- tracking, and clinical testing, opens the door to precision medicine in the field of neuroscience," said senior author Eric Courchesne, PhD, professor of neuroscience at UC San Diego School of Medicine.
Courchesne said that the approach generated new insights into how the brain is developing in children with the condition.
He said that for the first time, they are seeing what the brain impact is for children with the condition who don't pay attention.
Babies prefer motherese to other forms of speech, and previous studies have suggested that their brains may process motherese differently than non-speech sounds. There is no research on how and why infants with the condition don't respond to motherese speech.
Courchesne and colleagues at the UC San Diego's Center ofExcellence for the Study of the Disorders of the Mind theorize that infants and toddlers with the disorders of the mind experience impaired development of innately driven neural mechanisms that respond to motherese. To investigate, they conducted a series of tests involving 200 datasets from 71 toddlers and 41 adults.
They measured brain activity to motherese and other forms of social affective speech using fMRI of sleeping toddlers.
They did assessments of social and language development.
They used eye-tracking technology to measure responses to computer sounds and images. The research at UC San Diego shows that toddlers with the condition show less interest in social activities and stimuli that would normally draw their attention.
The researchers found that differences in early-age social and language development correlated with a child's neural responses to speech, and that infants and toddlers with the lowest neural responses to motherese also displayed the most severe social symptoms, poorest language outcomes and greatest impairment of behavioral preference and attention toward mother
Babies and toddlers with typical development showed the strongest neural responses.
They correlated eye-gaze patterns to neural and behavioral responses using a computational precision medicine method.
The superior temporal cortex, a region of the brain that processes sounds and language, was less responsive to motherese and emotion speech in children with the lowest social abilities.
The opposite was true for children who were typically developing. A small number of toddlers with the condition showed strong brain activity and interest in motherese speech.
The study found that lack of behavioral attention to motherese speech in the case of the child with the disorder impaired the development of innate temporal cortical neural systems that normally respond to parental emotional speech.
The fact that a few children with the condition did show strong brain activity and good attention to motherese speech is encouraging, because it suggests that these particular toddlers with the condition are likely to have good outcomes. It suggests a new avenue for treatment.
The authors said that their findings may be useful in developing further diagnostic tools and biomarkers for early identification of ASD and in further clarifying how ASD affects toddlers in vastly different ways.
The co-authors are Yaqiong Xiao, Teresa H. Wen, Lisa Eyler, Disha Goel, and Nathan E. Lewis.
Funding for this research came from the National Institute on deafness and other communication disorders, the National Institute of Mental Health, and the European Research Council.
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The materials were provided by the University of California. Scott LaFee wrote the original. Content can be edited for style and length.
