A team of scientists from the University of Tokyo has finally solved the ongoing conundrum of why babies kick in the womb.
Using motion capture technology and a musculoskeletal computer model, the team analyzed muscle communications in newborns’ and infants’ bodies. They then identified patterns of muscle interactions based on the infants’ random body movements.
The team discovered that the neurons within each muscle produce muscular contractions that activate “sensors.”
These random movements assist in the development of the sensorimotor system, which includes the sensory organs, nervous system and motor controls. The team’s model shows these movements help infants learn to control their bodies while still in the womb.
The discovery could lead to new methods for detecting and treating neurodegenerative disorders, such as multiple sclerosis and cerebral palsy.
Project Assistant Professor Hoshinori Kanazawa from the Graduate School of Information Science and Technology explained that past research on sensorimotor development was mainly centered on “kinematic properties, muscle activities which cause movement in a joint or a part of the body.”
However, 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.
Recordings of the joint movements of 12 newborns less than 10 days old and 10 infants of less than 3 months contributed to these findings.
The scientists were surprised to see that infants’ movements strayed during spontaneous movement as they discovered sensorimotor interactions. The team 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. In addition to this, our findings provide a conceptual linkage between early spontaneous movements and spontaneous neuronal activity.
During the study, newborns displayed more random movements compared to the predictable, patterned movements of the infant group.
Next, Kanazawa plans to research how “sensorimotor wandering” affects walking and reaching, as well as more complex behavioral developments and cognitive functions.