When a baby kicks a mother from within her womb, the mother may joke that the baby could be angry, ready to come out, or is destined to become the world's next great soccer player. But researchers at Rutgers University-Newark have determined that these kicks mean much more than those light-hearted explanations and may hold the key to how an infant's brain develops in its earliest stages.
In a paper published in the journal Nature, Gyorgy Buzsaki, Professor in Neuroscience, Rustem Khazipov, a Visiting Professor from INSERM, Marseille, France, and their team of researchers contend that critical information may be provided to the sensory areas of the developing brain through an individual's own movements rather than just sensory inputs, as was previously believed. In the article, "Early motor activity drives spindle bursts in the developing somatosensory cortex," the researchers describe how they examined the relationship between movement and electrical activity in the somatosensory area of the cerebral cortex in developing rats. The cerebral cortex is largely responsible for higher brain functions which include sensation, voluntary muscle movement, thought, reasoning and memory.
Rat pups in their litter display frequent muscle twitches and non-directed limb and whole body jerks, which are similar to human fetal movements. By studying the relationship between these movements and neuronal activity in the sensory part of the cerebral cortex, the researchers determined that the information provided to the developing brain by these random movements are critical for creating the proper representation of the body in the sensory cortex. By analogy, spontaneous kicks babies perform during the late stages of pregnancy should perform the same service for the human sensor
"Brain activity can occur independently of movement, but it is useless unless it is somehow tied to the events in the surrounding world," Dr. Buzsaki notes. "What we have found is that the very first pattern in the somatosensory part of the cortex is under the supervised control of the skeletal muscle system. The physical layout basically constrains what kind of activity should occur in the somatosensory representation. Without movement, sensory stimuli will still get into the brain and produce some activity but those inputs remain in abstract space and cannot be related to the body or anything in the real world."
Additionally, the research may offer clues as to how the brain determines whether the world around us is three dimensional and how the brain measures metric distances between body parts. Without such information it is impossible for individuals to perform even a simple sensorimotor coordination task, such as scratching one's nose.
"It is our conclusion that the developing brain never learns to sense anything unless it is able to move the sensors in the environment," Dr. Buzsaki explains. "Think about what you would see if neither your eyes nor your body could have moved since you were born. You would not be able to tell what is closer or what is distant, whether an object is the same when it is near or far from you or when it is partially covered by something. It is the movement of the eyes and body that verifies those relationships."