Related Experiment Video
Updated: Mar 23, 2026
Quantifying Learning in Young Infants: Tracking Leg Actions During a Discovery-learning Task
Published on: June 1, 2015
Developmental changes in intralimb coordination during spontaneous movements of human infants from 2 to 3 months of
Yoshiyuki Ohmura1, Hirotaka Gima2, Hama Watanabe2
1Department of Mechano-Informatics, Graduate School of Information Science and Technology, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan. ohmura@isi.imi.i.u-tokyo.ac.jp.
Insights
Infant joint movements become more independent around 2-3 months old. This dissociation in knee-ankle coordination coincides with increased knee extension, suggesting developing neural control mechanisms.
Area of Science:
- Developmental neuroscience
- Motor control
- Infant biomechanics
Background:
- Human infants exhibit diverse spontaneous movements in early life.
- The developmental trajectory of intralimb coordination during infancy remains incompletely understood.
- A significant shift in movement patterns occurs around 2 months of age.
Purpose of the Study:
- To investigate the developmental changes in knee-ankle coordination during spontaneous movements in infants aged 2 to 3 months.
- To quantify the relationship between knee and ankle joint movements.
- To explore the emergence of independent joint control.
Main Methods:
- Utilized multiple attitude sensors to capture 3D angular motion of knee and ankle joints.
- Acquired time-series data for knee joint angle and 2D ankle motion (sagittal and frontal planes).
- Calculated temporal correlation and regression slopes to quantify knee-ankle dissociation.
Main Results:
- Infants aged 3 months demonstrated a pronounced tendency for knee joint extension, particularly on the left side.
- Three-month-old infants exhibited greater independence of ankle joint motion compared to 2-month-old infants.
- The development of dissociated knee-ankle movements was concurrent with the increased prevalence of knee extension.
Conclusions:
- The transition from synchronized to dissociated intralimb joint movements during spontaneous activity suggests evolving neural pathways.
- Development of cortical and/or subcortical mechanisms around 2 months of age likely facilitates selective activation and inhibition of joint movements.
- These findings provide insights into the neural underpinnings of early motor development and coordination.
Abstract:
Human infants show a variety of spontaneous movements in the first few months of life. Although the pattern of spontaneous movements changes at approximately 2 months of age, the precise mechanism that governs the developmental changes in intralimb coordination remains unclear. In the present study, we focused on knee-ankle coordination during spontaneous movements of human infants from 2 to 3 months of age. Multiple attitude sensors were used to measure three-dimensional angular motion of knee and ankle joint motions. We acquired a one-dimensional time series of the knee joint angle around the putative hinge joint and a two-dimensional time series of ankle motions on the putative sagittal and frontal plane. First, we found that 3-month-old infants show a significant predominance to extend their knee joints, remarkably so on the left side. To quantify dissociated motions of the knee and ankle, we calculated the temporal correlation and the regression slope between them. We observed that 3-month-old infants moved their ankle joints more independently of knee motions than 2-month-old infants. Finally, we found that dissociated motions of the knee and ankle simultaneously develop with knee extension predominance. The developmental change from synchronization to dissociation of intralimb joint movements during spontaneous movements suggests that the development of the cortical and/or subcortical mechanism may mediate selective activation and inhibition of joint motions at approximately 2 months of age.
Related Concept Videos
01:14Piaget's Stage 1 of Cognitive Development
Exploration...
01:18Hierarchy of Motor Control
01:09Changes in the Appendicular Skeleton with Age
Initially, the limb buds consist of a core of mesenchyme covered by a layer of ectoderm. The ectoderm at the end of the limb bud thickens to form a narrow crest called the apical ectodermal ridge. This ridge stimulates the underlying...