March 26, 2013
Study Says Angry Tones Influence How Baby Brains Process Emotion
April Flowers for redOrbit.com - Your Universe Online
Parents have long known that the tone of their voice affects a baby's mood, but a new study from the University of Oregon shows that a baby's exposure to parental arguments is associated with the way the infant's brain processes stress and emotions.
Babies' brains develop in response to the environments and experiences that they encounter. This high level of neural plasticity, however, comes with a certain degree of vulnerability. Severe stress, such as maltreatment or institutionalization, can have a significant negative impact on child development, according to previous research. Graduate student Alice Graham and her advisors, Phil Fisher and Jennifer Pfeifer, wondered what impact more moderate stressors might have on that vulnerability.
“We were interested in whether a common source of early stress in children´s lives — conflict between parents — is associated with how infants´ brains function,” explained Graham.
The research team took advantage of recent developments in functional magnetic resonance imaging (fMRI) with infants to answer their questions. The study participants were twenty infants, ranging in age from 6 to 12 months. They were brought into the lab at their regular bedtimes. While the children slept in the scanner, they were presented with nonsense sentences spoken in neutral, happy, mildly angry and angry tones by an adult male.
“Even during sleep, infants showed distinct patterns of brain activity depending on the emotional tone of voice we presented,” says Graham.
Babies from high-conflict homes showed a greater reactivity to very angry voice tones in brain areas linked to stress and emotional regulation. These areas include the anterior cingulate cortex, the caudate, the thalamus and the hypothalamus.
According to previous animal research, these brain areas play an important role in the impact of early life stress on development. Graham´s study suggests that the same might be true in human babies. Apparently, infants are not oblivious to their parents' conflicts, the study shows, and exposure to such conflicts may influence the way babies' brains develop to process emotions and stress.