The baby's spontaneous movements are important for the development of the coordinated sensorimotor system


Summary: A new study reveals that the spontaneous and random movements that babies make help in the development of the sensorimotor system.

Source: university of tokyo

Baby’s spontaneous, random movements aid in the development of their sensorimotor system, according to new research led by the University of Tokyo.

Detailed motion capture of newborns and infants was combined with a musculoskeletal computer model to allow researchers to analyze communication between muscles and sensations throughout the body.

The researchers found patterns of muscle interaction developing based on the babies’ random exploratory behavior, which would later enable them to perform sequential movements as babies.

Understanding better how our sensorimotor system develops can help us gain insight into the origin of human movement, as well as past diagnoses of developmental disorders.

From birth – and even in the womb – babies begin kicking, wiggling and moving seemingly without purpose or external stimulus. These are called “spontaneous movements” and researchers believe that they have an important role to play in the development of the sensorimotor system, i.e. the ability to control muscles, movement and coordination.

If researchers can better understand these seemingly random movements and how they are involved in early human development, we might also be able to identify early indicators of certain developmental disorders, such as cerebral palsy.

Currently, there is limited knowledge about how newborns and infants learn to move. “Previous research on sensorimotor development has focused on kinematic properties, muscle activities that cause movement in a joint or body part,” said project assistant professor Hoshinori Kanazawa of the Graduate School of Information Science and Technology .

“However, our study focused on muscle activity and sensory input signals to the whole body. By combining a musculoskeletal model and a neuroscientific method, we found that spontaneous movements, which appear to have no explicit task or purpose, contribute to coordinated sensorimotor development.”

First, the team recorded the joint movements of 12 healthy newborns (less than 10 days old) and 10 infants (about three months old) using motion capture technology. Next, they estimated the babies’ muscle activity and sensory input signals with the help of an infant-scale full-body musculoskeletal computer model they created.

Finally, they used computer algorithms to analyze the spatiotemporal (space and time) characteristics of the interaction between input signals and muscle activity.

“We were surprised to see that during spontaneous movement, the babies’ movements ‘wandered’ and they sought out various sensorimotor interactions. We call this phenomenon ‘sensory-motor wandering,’” said Kanazawa.

This shows a baby with its movements mapped
Markers for the motion capture camera were smoothly applied to the baby’s limbs, head and tummy, allowing the team to capture the full range of motion. Credit: 2022 Kanazawa et al.

“It has been commonly assumed that the development of the sensorimotor system generally depends on the occurrence of repeated sensorimotor interactions, which means that the more you do the same action, the more likely you are to learn and remember it.

“However, our results imply that babies develop their own sensorimotor system based on exploratory behavior or curiosity, so that they do not just repeat the same action, but a variety of actions. Furthermore, our findings provide a conceptual link between early spontaneous movements and spontaneous neuronal activity.”

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This shows parents sleeping next to their baby.

Previous studies in humans and animals have shown that motor behavior (movement) involves a small set of primitive muscle control patterns. These are patterns that can typically be seen in task specific or cyclic movements such as walking or reaching.

The results of this latest study support the theory that newborns and infants can acquire sensorimotor modules, i.e., synchronized muscle activities and sensory inputs, through spontaneous whole-body movements without an explicit purpose or task.

Even through sensorimotor wandering, the infants showed an increase in coordinated whole-body movements and anticipatory movements. The movements performed by the infant group showed more common patterns and sequential movements, compared to the random movements of the newborn group.

Next, Kanazawa wants to see how sensorimotor wandering affects later development such as walking and reaching, along with more complex behaviors and higher cognitive functions.

“My original background is in child rehabilitation. My big goal with my research is to understand the underlying mechanisms of early motor development and find knowledge that helps promote baby development.”

About this neurodevelopment research news

Author: Press office
Source: university of tokyo
Contact: Press Office – University of Tokyo
Image: The image is credited to Kanazawa et al.

Original search: Discoveries will appear in PNAS