Babies, even in the womb, constantly move and wiggle without any apparent reason or external stimulation.

If you’ve ever spent time with a baby, you’ve undoubtedly observed they tend to be very active and don’t stay still for long periods of time.

These are known as “spontaneous movements,” and scientists believe they play a critical role in the growth of the sensorimotor system, which controls our muscles, movement, and coordination.

If we can get a better understanding of these apparently random motions and their role in early human development, we may be able to spot early signs of developmental diseases such as cerebral palsy.

There is still a lack of understanding about how newborns and infants learn to move their bodies.

According to Project Assistant Professor Hoshinori Kanazawa of the Graduate School of Information Science and Technology, earlier studies into sensorimotor development have concentrated on “kinematic properties,” or the actions of muscles that create motion at a given joint or body part.

But the new “study focused on muscle activity and sensory input signals for the whole body,” adds the professor. 

“By combining a musculoskeletal model and neuroscientific method, we found that spontaneous movements, which seem to have no explicit task or purpose, contribute to coordinated sensorimotor development.”

To begin, the group used motion capture equipment to record the joint motions of 12 healthy neonates (less than 10 days old) and 10 young babies (about 3 months old).

Next, they used a whole-body, infant-scale musculoskeletal computer model they had developed to assess the newborns’ muscle activity and sensory input data.

In the end, they employed computer algorithms to conduct an analysis of the spatiotemporal (both space and time) characteristics of the relationship between the input signals and the activity of the muscles.

“We were surprised,” remarks Kanazawa, “that during spontaneous movement, infants’ movements “wandered” and they pursued various sensorimotor interactions. We named this phenomenon ‘sensorimotor wandering’.”

Sensorimotor system development is widely thought to rely on the occurrence of recurrent sensorimotor contacts, which means that the more often an action is performed, the more probable it is that the movement will be learned and remembered.

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

Studies on both people and animals have shown that movement is controlled by a small number of basic muscle control patterns.

These are patterns that are often seen in movements that are specific to a task or happen over and over again, like walking or reaching. This recent research supports the idea that neonates and babies may learn sensorimotor modules—synchronized muscle actions and sensory inputs—through spontaneous whole-body motions without a goal or objective.

Even while doing sensorimotor wandering, the babies got better at moving their whole bodies together and moving in advance.

Compared to the newborn group’s random movements, the baby group’s motions had more recurring patterns and sequential movements.

Next, Kanazawa plans to investigate how sensorimotor wandering influences later stages of development, including more complicated actions and higher cognitive skills, such as walking and reaching.

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

Source: 10.1073/pnas.2209953120

Image Credit: Getty