This study was done to examine the brain functioning of depressed versus nondepressed mothers when hearing their infant’s cry. The brains were studied using functional MRI (fMRI). It was found that depressed mothers showed a far lower neural activation in specific areas of the brain, as compared to non-depressed mothers. It was also found that mothers with severe depressive symptoms were found to have lesser activation as compared to mothers with milder symptoms.
Mothers react to an infant’s cry with a complex emotional and behavioral response. This response encourages bonding between the mother and the infant and ensures that the infant’s needs are addressed. Previous studies on functional MRI concluded that an infant’s cry produces widespread neural activation in several cortical areas, as well as in the thalamic region of the mother’s brain. However, these studies were performed in normal mothers. Depressed mothers are known to respond less sensitively to their infants. They also engage less in positive interactions with infants. This study was aimed at finding out whether an infant’s cry stimulated different neural activations in normal mothers, as compared to depressed mothers.
* Twenty two mothers with infants aged between 15 and 18 months were selected for the study. Eleven mothers were suffering from depression, at the time of study.
* Three sound stimuli were prepared. The first was a recording of the crying of an infant belonging to a specific mother; the second was the crying of an infant not belonging to that mother; and, the third sound was a “control non crying sound” matching in frequency and strength to an infant’s cry.
* These sounds were presented in a random manner, via earphones, while the mothers underwent MRI scanning. The brain region activated was noted on imaging.
* After the scanning was completed, mothers rated qualities of sound like urgent, grating, arousing, piercing, discomforting, aversive etc., on a 5 point scale.
* As compared to depressed women, neuronal activation in non-depressed mothers who were listening to their own infant’s cry showed a greater response than to the “control” sound stimulus.
* The regions activated in the brain of non-depressed women were related to motivational cognition, emotion and visual sensory processing, coupled with auditory stimulus. Depressed mothers as a group failed to show such activation in these areas.
* The non-depressed group showed greater activity in brain areas like striatum and thalamus, while these areas were less activated in depressed mothers.
* Mothers with lower depressive symptoms had stronger activation of specific brain regions than mothers with higher depressive symptoms.
This study demonstrated that neuronal activation in specific areas of the brain may differ between non-depressed and depressed mothers after hearing her own infant’s cry. But this finding must be correlated with the mother’s subjective experience of parenting. There were some areas of emotional brain activated in the same manner in both non-depressed and depressed mothers. This might mean that depressed mothers also respond emotionally to the sound of an infant’s cry; only these might be negative emotions. More research in this direction is necessary.
Positive reinforcements in emotions and behaviour occur when a mother responds normally to an infant’s distress signal. Previous studies noted that the areas of the brain involved in motivation and reward are activated in a mother’s brain, when she responds to the crying of her infant. This study found that in depressed mothers, the activation in these specific areas is lower, as compared to that in the non-depressed mothers. The exact cause of the depression may vary. It possibly indicates that depressed mothers might not be able to generate positive reinforcement and might develop negative emotions while interacting with their infants.
For More Information:
A Cry in the Dark: Depressed Mothers Show Reduced Neural Activation to their Own Infant’s Cry
Publication Journal: Social Cognitive and Affective Neuroscience, January 2011
By Heidemarie K. Laurent; Jennifer C. Ablow; University of Wyoming and University of Oregon
*FYI Living Lab Reports Are Summaries of the Original Research.