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

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

Source: University of Tokyo

A baby’s spontaneous and random movements help the development of its sensorimotor system, according to new research led by the University of Tokyo.

Detailed motion capture from infants and toddlers was combined with a musculoskeletal computer model to allow researchers to analyze communication between muscles and sensation throughout the body.

The researchers found patterns of muscle interaction that develop based on infants’ random exploratory behavior that would later enable them to perform sequential movements as infants.

Better understanding of how our sensorimotor system develops could help us understand the origin of human movement, as well as earlier diagnoses of developmental disorders.

From birth, and even in the womb, babies begin to kick, wiggle, and move seemingly without purpose or external stimulation. These are called “spontaneous movements” and researchers believe they play an important role in the development of the sensorimotor system, meaning 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 may also be able to identify early indicators of certain developmental disorders, such as cerebral palsy.

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

“However, our study focused on muscle activity and sensory input signals for the whole body. By combining a musculoskeletal model and a neuroscientific method, we found that spontaneous movements, which seem to have no 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) and 10 young infants (about three months) using motion capture technology. They then estimated the infants’ muscle activity and sensory input signals with the help of a whole-body infant-scale musculoskeletal computer model they had created.

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

“We were surprised that during spontaneous movement, the infants’ movements ‘wandered’ and continued various sensorimotor interactions. We called this phenomenon ‘sensorimotor wandering,'” Kanazawa said.

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

“However, our results implied that infants develop their own sensorimotor system based on exploratory behavior or curiosity, so that they are not only repeating the same action but a variety of actions. In addition to “Thus, our findings provide a conceptual link between early spontaneous movements and spontaneous neural activity.”

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 cyclical or task-specific movements such as walking or reaching.

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

Even through sensorimotor ambulation, 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 look at how sensorimotor wandering affects later development, such as walking and reaching, along with more complex behaviors and higher cognitive functions.

“My original training is in child rehabilitation. My big goal through my research is to understand the underlying mechanisms of early motor development and find insights that help promote infant development.”

About this neurodevelopmental research news

Author: Press Office
Source: University of Tokyo
Contact: Press Office – University of Tokyo
Image: Image is credited to Kanazawa et al

Original Research: Findings will appear in PNAS