Related Experiment Videos
The asymmetrical tonic neck reflex in normal full-term infants
Insights
The asymmetrical tonic neck reflex is present in infants from 1 to 12 weeks old. This reflex
Area of Science:
- Pediatric neurology
- Developmental pediatrics
- Infant motor development
Background:
- The asymmetrical tonic neck reflex (ATNR) is a primitive reflex crucial for early motor development.
- Understanding the ATNR's presence and pattern in healthy infants is essential for developmental assessments.
Purpose of the Study:
- To investigate the presence and characteristics of the asymmetrical tonic neck reflex in normal infants aged 1 to 12 weeks.
- To document the temporal pattern of the ATNR in both upper and lower limbs during early infancy.
Main Methods:
- Longitudinal observation of 12 healthy infants over the first 12 weeks of life.
- Seven observational visits including the first, second, and every other week thereafter.
- Videotaping of spontaneous supine behavior to record reflex responses in arms and legs.
Main Results:
- The asymmetrical tonic neck reflex was consistently observed in infants' arms throughout the study period, peaking at 6 weeks.
- The reflex was present in the legs, with the longest duration noted at the first week.
- Differential limb movement patterns were observed, with the 'face' side showing more movement than the 'skull' side in both arms and legs at specific time points.
Conclusions:
- The asymmetrical tonic neck reflex is a verifiable component of normal infant posture and movement within the first 12 weeks.
- The manifestation and temporal pattern of the ATNR differ between the arms and legs during early development.
Abstract:
The purpose of this study was to determine whether the asymmetrical tonic neck reflex was present in normal 1- to 12-week-old infants. Twelve infants were observed seven times within the first 12 weeks: at the first and second week and every other week thereafter. Spontaneous behavior was videotaped while the infant lay supine. Infants maintained a head-turned posture during every visit. The asymmetrical tonic neck reflex was present: 1) in the infants' arms during every visit, at a maximum at the sixth week; 2) in their legs, with the longest duration of the response at the first week's visit; and 3) in both arms and legs, with no change throughout seven visits. There were more movements of the face arm than of the skull arm during the seven visits, and the additional movements were in the extension range. The face leg moved more than the skull leg, but only at the 6th, 8th, and 10th weeks. The study confirms that the asymmetrical tonic neck reflex can be observed in the posture and movement of normal infants and that the pattern of appearance of the reflex differs in arms and legs.