Soothing a baby is any mother or caregivers’ ultimate goal when their infant is crying. Babies’ universal indication of any concern, distress, pain, hunger, or desire is communicated by crying; parents endlessly attempt comforting techniques to relieve their helpless infant. A common response is for a mother to immediately pick the crying baby up and rock or walk with them gently in her arms (Gammie, 2013). Often times, the helpless infant nearly instantly stops or reduces their cries; however, as soon as their mother again puts the baby down, often the cries once again ensue. This recurring pattern exemplifies the elicited automatic calming response that infants exhibit in response to being carried. This comforting mechanism is not selective to human parents exclusively, this dynamic interaction is a comforting method utilized by parents of various mammalian species.
Various other mammals, such as felines and rodents demonstrates what is called the “transport response” in which the crying young assumes an immobile posture while their mother transports them (Esposito et al., 2013). Often the response is relieved stress exhibited by reduced vocal cries. This dynamic “transport response” is also seen in species of mouth-carrying primates (galagos); how is this transport response translated to humans and what is happening in the brain to activate this soothing response?
One study at the RIKEN Brain Science Institute in Saitama, Japan explored the infant physiological responses to their mothers, aiming to further examine this effective coddling parent technique. More specifically, the response of infants under the age of 6 months was examined as their mothers’ exhibited different behaviors. This study examined the behavior, vocalization, and electrocardiogram of infants during three experimental conditions: lying in a crib, being held by their mother in a stationary crib, and being carried by their mother as she walked continuously. In comparison to being in their crib, both being held by a stationary mother, as well as being carried by a walking mother exhibited decreased voluntary movement, vocalization, as well as a rapidly declining heart rate; a similar pattern of results was shown between infants being held by a stationary mother and infants being carried by a walking mother. These results showed that physical contact from the mother elicits comfort in the infant; mobile transport combined with physical contact elicits even greater comfort.
What is happening neurologically to produce such calming responses, as exhibited both physiologically and behaviorally? Exhibited by infants in this study, heart rate analysis identified differences in parasympathetic activity based on interbeat measurements; increased duration of interbeat index measurements within the infants being carried by a walking mother indicated that infants were more relaxed. Previous research suggests that maternal physical touch combined with rocking motion provides vestibular-proprioceptive stimulation; these results suggest that walking movement has a similar stimulating mechanism, resulting in heightened calming effects on infants. Furthermore, maternal walking provides infants with calming sensory inputs in a synergic manner, eliciting possibly the most effective calming response (Esposito et al., 2013).
Works Cited:
Esposito, G., Yoshida, S., Ohnishi, R., Tsuneoka, Y., del Carmen Rostagno, M., Yokota, S., … & Kuroda, K. O. (2013). Infant calming responses during maternal carrying in humans and mice. Current Biology, 23, 739-745.
Gammie, S. C. (2013). Mother–Infant Communication: Carrying Understanding to a New Level. Current Biology, 23, R341-R343.
On Psychology and Neuroscience 
I took Lifespan Development in the fall and we talked a lot about different parenting styles especially in regards to carrying. In some cultures babies are strapped onto their mothers or siblings all day and are therefore involved in everything they do. In American culture we have a lot devices to hold our babies for us–swings, chairs, strollers, etc. It would be cool to see if the brain of babies raised in different cultures are affected differently when they are held. We also talked about kangaroo care and how the body on body contact can be really beneficial to babies. It is interesting to look at these issues through different frameworks/ perspectives–developmentally and biologically. There seems to be a lot of debate about if parents should pick their babies up when they cry or if they should be left to self-soothe and I do not think a lot of people consider looking to at the brain to answer these types of questions but clearly we can learn a lot from what is going on in the brain when mothers engaged in different behaviors with their infants.
This article was also interesting after just finishing our drug unit in Bio Basis. The discussion of the calming effects of carrying reminded me of certain drugs that have calming affects. It is interesting that something psychical like carrying for infants can have a similar outcome to taking a drug.
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One thing that this article made me think of was when my cousins had children who were quickly calmed by skin-to-skin contact. The carrying and walking talked about here also worked, but my cousins really promoted their kids enjoying skin contact with the person holding them because it was comforting and calming for the children. I think it would be very interesting to do a study comparing the crying baby in the crib’s heart rate and overall calmness to the baby crying while being walked around and to a baby being walked around who has skin contact with their mother.
I think it would also be interesting to investigate a similar effect in teens and in adults. I know there are hormones released when you receive a hug, but is there a different bodily reaction if someone is very upset or crying and they are hugged by another person. If the hormones differ from those released by a normal hug, that might say something about what pathways are activated (or deactivated) by the person’s emotional disturbances and how that affects later pathways (the pathway releasing the hug’s hormones).
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I wonder which neural pathway results in the calming effect. It would be interesting to see fMRI images of babies as they are being carried/rocked by their mothers (although it would be problematic for the fMRI to adjust to the movement and get a clear picture) Or, as generally known, not all babies cry for the same intensity/time. It’d be nice to see a further study investigating the structural differences in the infant brains who cry a lot or not. Maybe it’ll have something to do with this touch+motion circuits that normally calm babies down as shown in this study. Just a thought.
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