Spontaneous and random movements of the baby promote the development of the sensorimotor system

According to a new study conducted by the University of Tokyo, the baby’s spontaneous and random movements promote the development of its sensorimotor system. Detailed capture of the movements of newborns and infants was combined with a musculoskeletal computer model, to allow researchers to analyze the communication between muscles and sensations throughout the body. The researchers found patterns of muscle interaction developing based on babies’ random exploratory behavior, which would later allow them to perform sequential movements as infants. A better understanding of the development of our sensory-motor system could help us better understand the origin of human movement as well as diagnose developmental disorders earlier.

If you’ve spent time with a baby, you’ll probably notice that they barely stay still. From birth -; and even in the womb -; babies begin to kick, squirm, and move seemingly without purpose or external stimulation. These are called “spontaneous movements” and researchers believe they have an important role to play in the development of the sensory-motor system, i.e. our ability to control our muscles, our movements and our coordination. . If we 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, knowledge about how newborns and infants learn to move their bodies is limited.

Previous research on sensorimotor development has focused on kinematic properties, the muscular activities that cause a joint or body part to move. 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 discovered that spontaneous movements, which seem to have no explicit task or purpose, contribute to coordinated sensorimotor development.”

Hoshinori Kanazawa, Assistant Project Professor, Graduate School of Information Science and Technology

First, the team recorded the joint movements of 12 healthy newborn babies (less than 10 days old) and 10 young infants (about 3 months old) using motion capture. Next, they estimated the babies’ muscle activity and sensory input signals using an infant-scale whole-body musculoskeletal computer model they had created. Finally, they used computer algorithms to analyze the spatio-temporal characteristics (both spatial and temporal) of the interaction between input signals and muscle activity.

“We were surprised that during spontaneous movements, infants’ movements ‘wander’ and they pursue various sensorimotor interactions. We named this phenomenon ‘sensorimotor wandering,'” Kanazawa said. “It has been commonly accepted 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. system based on exploratory behavior or curiosity, so that they do not simply repeat the same action but a variety of actions.In addition to this, our findings provide a conceptual link between early spontaneous movements and the 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 usually be observed in task-specific or cyclical 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 a goal. nor explicit task. Even through sensorimotor wandering, babies showed increased coordinated whole-body movements and anticipatory movements. The movements made by the infant group showed more common patterns and sequential movements, compared to the random movements of the newborn group.

Next, Kanazawa wants to examine how sensorimotor wandering affects later development, such as walking and reaching, as well as more complex behaviors and higher cognitive functions. “My initial training is in infant rehabilitation. My big goal through my research is to understand the underlying mechanisms of early motor development and to find insights that will help promote baby development.”