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Frame-by-Frame Video Analysis of Idiosyncratic Reach-to-Grasp Movements in Humans
Published on: January 15, 2018
Longitudinal study of unimanual actions and grasping forces during infancy
Giuseppina Sgandurra1, Francesca Cecchi, Stefano Marco Serio
1Scuola Superiore Sant'Anna, Pisa, Italy.
Insights
Infants develop significant unimanual grip force between 18 and 30 weeks, with early bimanual play emerging. This study tracked infant grasping development using a novel biomechatronic system.
Area of Science:
- Developmental neuroscience
- Infant motor development
- Biomechanics
Background:
- Grasping is a key infant developmental milestone.
- Research on infant reaching is more common than on grasping and grip force development.
- Understanding grip force development is crucial for assessing neurological maturation.
Purpose of the Study:
- To investigate the development of palmar grasp and power grip force in infants.
- To assess unimanual and bimanual grasping actions with centrally and laterally placed objects.
- To utilize an ecological approach for studying infant grasping development.
Main Methods:
- Longitudinal study of ten infants from 18 to 41 weeks, with 2-week intervals.
- Utilized the "biomechatronic gym" platform for measuring reaching and grasping forces.
- Objects were placed in three positions: body midline, ipsilateral, and contralateral shoulder.
Main Results:
- Significant increase in unimanual power grip force from 18 to 30 weeks, plateauing by 41 weeks.
- Early infant tendency towards bimanual play with objects in various positions.
- Increased unimanual successful power grasping for central tasks and midline crossing with age.
Conclusions:
- Infant grasping and grip force development show distinct patterns in early life.
- Maturation of the corticospinal tract may influence these developmental changes.
- The biomechatronic gym provides a valuable tool for ecological assessment of infant motor skills.
Abstract:
Learning to grasp an object is an important milestone in neurological development during infancy. Several studies report development of reaching in infants but less attention is devoted to reaching with successful grasping and to development of grip force. This study investigates, in the first weeks of life, the development of palmar grasp both for assessment of unimanual/bimanual grasping actions in centrally and laterally placed objects and for measurement of exerted power grip force. We longitudinally examined ten infants from 18 weeks to 41 weeks, at 2-weeks intervals, with a toy placed in three positions (body midline, ipsilateral and contralateral shoulder). Our main aim was to study this development through an ecological approach. This was possible thanks to the use of the "biomechatronic gym", a new platform purposively developed for measuring reaching and grasping forces. These longitudinal trials showed a good level of acceptance and involvement by infants of the entire system. The results demonstrated a significant increase in unimanual power grip force between the 18th and 30th week followed by a flat period until the 41st week; we also ascertained an early tendency to play bimanually with centrally and laterally placed objects with a subsequent increase in all ages of unimanual successful power grasping both for central task and midline crossing. These developmental changes may be, in part, related to organism constraints such as maturation of the corticospinal tract.
