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The relationship between sucking and grasping in the human newborn: a precursor of hand-mouth coordination?
Insights
In newborns, sucking enhances grasp strength and duration, suggesting it may be dominant over grasping. Both reflexes are part of an integrated system crucial for developing hand-mouth coordination.
Area of Science:
- Neonatal development
- Developmental psychology
- Neuroscience
Background:
- Hand-mouth coordination is vital for infant development.
- Grasping and sucking reflexes are early sensorimotor behaviors.
- Understanding their interplay may reveal precursors to coordinated movements.
Purpose of the Study:
- To investigate the relationship between grasping and sucking reflexes in human newborns.
- To determine if these reflexes influence each other's performance.
- To explore their correlation with central nervous system maturity.
Main Methods:
- Human newborns of varying gestational ages were studied.
- Grasping was elicited by backward tilting with a grasp bar.
- Sucking and grasping-while-sucking responses were recorded and analyzed for strength, duration, frequency, and amplitude.
Main Results:
- Grasping did not significantly affect sucking responses.
- Sucking significantly increased both the strength and duration of the grasp.
- Both reflexes showed a stronger correlation with central nervous system maturity indices when elicited together.
Conclusions:
- Sucking appears to be dominant over grasping in human newborns.
- Grasping and sucking function as an integrated system.
- This integrated system likely forms the foundation for developing hand-mouth coordination.
Abstract:
The relationship between grasping and sucking, a possible precursor of hand-mouth coordination, was examined in human newborns of varying gestational ages. Grasping was elicited by rapidly tilting the infant backwards while he rested on a padded board and held a grasp bar. Infants were tilted 4 times under each of 3 conditions: grasping, sucking, and grasping-while-sucking. The dependent variables were strength and duration of grasp and frequency and amplitude of sucks during the 15 sec following the tilt. The results indicated that grasping did not affect sucking but that sucking increased the strength and the duration of the grasp. Furthermore, either response system was more highly correlated with indices of maturity of the central nervous system when elicited in the presence rather than the absence of the other. We conclude that in human newborns sucking may be dominant over grasping but that both are part of an integrated system which may form the basis for the development of hand-mouth coordination.