New research led by the University of Tokyo has found that spontaneous, random movements made by babies aid in the development of their sensorimotor system, which is responsible for controlling muscles, movement, and coordination.
By using motion capture technology and a musculoskeletal computer model to analyze the interaction between muscles and sensation across the whole body in newborns and infants, researchers were able to observe patterns of muscle interaction based on the babies’ exploratory behavior, which would later enable them to perform sequential movements as infants.
Better understanding the role of these random movements in early human development could also help identify early indicators for certain developmental disorders, such as cerebral palsy. Project Assistant Professor Hoshinori Kanazawa from the Graduate School of Information Science and Technology explained, “Our study focused on muscle activity and sensory input signals for the whole body. 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.”
Kanazawa added, “We were surprised that during spontaneous movement, infants’ movements ‘wandered’ and they pursued various sensorimotor interactions. We named this phenomenon ‘sensorimotor wandering.’ It has been commonly assumed that sensorimotor system development generally depends on the occurrence of repeated sensorimotor interactions, meaning 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 explorational behavior or curiosity, so they are not just repeating the same action but a variety of actions.”
The team’s findings also provide a link between early spontaneous movements and spontaneous neuronal activity. Previous studies on humans and animals have shown that motor behavior involves a small set of primitive muscular control patterns, which are typically seen in task-specific or cyclic movements, such as walking or reaching. However, the current study suggests that these primitive patterns emerge as a result of infants’ exploratory behavior.
The research highlights the importance of spontaneous movements in the development of the sensorimotor system and could lead to new approaches for understanding human movement and identifying developmental disorders.
This work was supported in part by JSPS KAKENHI (grant numbers 22H04770, 21K11495, and 21H00937).