by Jim Barlow, University of Oregon
April 8, 2013 (TSR) – Infants respond to their parents’ angry tone of voice, even when they’re sleeping. Being exposed to arguing parents is associated with the way babies’ brains process emotional tone of voice, according new research study.
Babies’ brains are highly plastic, allowing them to develop in response to the environments and encounters they experience. But this plasticity comes with a certain degree of vulnerability—research shows that severe stress, such as maltreatment or institutionalization, can have a significant, negative impact on child development.
Researchers wondered what the impact of more moderate stressors could have on infants. “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,” says Alice Graham, a doctoral student at the University of Oregon.
To answer the question, Graham and her faculty advisers Phil Fisher and Jennifer Pfeifer used functional magnetic resonance image (fMRI) scanning.
Twenty infants, ranging in age from 6 to 12 months, came into the lab at their regular bedtime. While asleep in the scanner, they were presented with nonsense sentences spoken in very angry, mildly angry, happy, and neutral tones of voice by a male adult.
“Even during sleep, infants showed distinct patterns of brain activity depending on the emotional tone of voice we presented,” Graham says.
The infants from high-conflict homes showed greater reactivity to very angry tone of voice in brain areas linked to stress and emotion regulation, such as the anterior cingulate cortex, caudate, thalamus and hypothalamus.
Previous research with animals has shown that these brain areas play an important role in the impact of early life stress on development—the results of the new study suggest that the same might be true for human infants.
Published in the journal Psychological Science, the new findings show that babies are not oblivious to parental conflicts, and exposure to them may influence the way babies’ brains process emotion and stress.
The research was supported by the Center for Drug Abuse Prevention in the Child Welfare System, the Early Experience, Stress, and Neurobehavioral Development Center, a Ruth L. Kirschstein National Research Service Award, and the Lewis Center for Neuroimaging at the University of Oregon.