Editors' ChoiceNeuroscience

Learning from Baby Steps

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Science Translational Medicine  14 Dec 2011:
Vol. 3, Issue 113, pp. 113ec205
DOI: 10.1126/scitranslmed.3003556

For many parents, the moment their baby begins to walk is exciting and memorable. Walking is no simple act, and it can take a year or longer for a baby to learn to walk independently and several more years to perfect efficient walking. One interesting question is whether an adult—with dramatically different size and proportions than a young child—acquires completely new sets of motor control mechanisms for walking, as is often assumed, or preserves the motor control schemes that came naturally right after birth.

Dominici and colleagues recently compared the leg muscle activation patterns during walking among newborns, toddlers, adults, and several small animals. For newborns, stepping movements were triggered while the researchers held the baby upright on a flat surface. Activities from about 24 leg muscles were recorded. The researchers first showed that complex muscle activity patterns during walking can be mathematically reduced to two to four basic patterns. When the researchers compared the patterns from babies and adults, they found that adults kept the two patterns used by babies and acquired two new patterns during development. This result shows that we modify and expand on motor patterns that we are born with as we grow instead of acquiring completely new patterns. Additionally, these researchers compared the four patterns that toddlers use during walking with muscle patterns derived from small animals, including rats, cats, and birds, and found that the patterns share similar characteristics across these species, which exhibit both bipedal and quadrupedal modes of locomotion.

These findings suggest that such motor patterns potentially have an ancient origin common to many different terrestrial vertebrates. Even though humans have evolved to walk in a bipedal manner, those basic ancestral movement elements have not been abandoned. Rather, we modify and expand on those patterns as we grow. Furthermore, from a rehabilitation perspective, such findings suggest that there might exist some basic and robust motor control mechanisms for walking in adult humans. When the nervous system is damaged, especially at the cortical level, we might be able to tap into such systems to at least partially restore someone’s ability to walk.

N. Dominici et al., Locomotor primitives in newborn babies and their development. Science 334, 997–999 (2011). [Abstract]

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