If you have a baby or have spent a lot of time with one, you will have realized that it does not stand still, and it is that from the moment a boy or girl comes into the world, and even when they are still a fetus in the womb, they begin to move. and to kick, although apparently they do so without a specific objective and without external stimulation. These are “spontaneous movements” and play an important role in the development of the sensorimotor system, that is, our ability to control our muscles, movement and coordination, according to a study led by the University of Tokyo that has been published in PNAS.
Better understanding these seemingly random movements and how they influence early childhood development can help identify early indicators of certain developmental disorders such as cerebral palsy, the researchers say. “Previous research on sensorimotor development has focused on kinematic properties, the muscle activities that cause movement in a joint or body part,” says project assistant professor Hoshinori Kanazawa of the Graduate School of Science and Technology. of the information.
“However – he adds – 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 appear to have no explicit task or purpose, contribute to coordinated sensorimotor development.”
Link between spontaneous movements and neural activity of the baby
First, the researchers recorded the joint movements of 12 healthy newborns (less than 10 days old) and 10 infants around three months old using motion capture technology. Next, they estimated the infants’ 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 spatiotemporal characteristics (both in space and time) of the interaction between input signals and muscle activity.
“Babies develop their own sensorimotor system based on exploratory behavior or curiosity, so they do not just repeat the same action, but a variety of actions”
“We were surprised that during spontaneous movement, the infants’ movements “wandered” and pursued various sensorimotor interactions. We call 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, which means that the more you repeat the same action, the more likely you are to learn and remember it. However, our results implied that babies develop their own sensorimotor system based on exploratory behavior or curiosity, so they do not just repeat the same action, but a variety of actions. In addition to this, our findings provide a conceptual link between spontaneous first movements and spontaneous neural activity.”
Previous studies in humans and animals have shown that motor (movement) behavior includes a small set of primitive muscle control patterns. These kinds of patterns can typically be seen in cyclical or task-specific movements, such as walking or reaching for something. The results of the new research support the theory that newborns and infants can acquire sensorimotor modules, that is, synchronized muscle activities and sensory input, through spontaneous whole-body movements without purpose or task.
The movements made by the three-month-old group showed more common patterns and sequential movements, compared to the random movements of the newborn group. Kanazawa’s next goal is to look at how sensorimotor ambulation affects later development, such as walking and reaching, along with more complex behaviors and higher cognitive functions. “My original experience is about child rehabilitation. My big goal through my research is to understand the underlying mechanisms of early motor development and find insights that help promote the development of the baby.”
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