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[Development of the blink reflex during the 1st 3 years of a child's life]
Insights
The blink reflex matures significantly in infants, with faster responses and lower thresholds by one year. Crying and non-REM sleep influence reflex excitability in young children.
Area of Science:
- Neuroscience
- Developmental Pediatrics
Context:
- The blink reflex is a crucial neurological indicator.
- Understanding its development in infants is vital for assessing neural maturation.
Purpose:
- To characterize the developmental trajectory of the blink reflex in infants from birth to 3 years.
- To investigate the influence of state (wakefulness, sleep, crying) on blink reflex parameters.
Summary:
- The study analyzed blink reflex components (R1 and R2) in 42 infants. Ipsilateral R1 latency decreased, and motor conduction velocity increased in the first six months. R2 responses became consistently bilateral after nine months. Thresholds for both R1 and R2 decreased with age. Crying facilitated the reflex, while non-REM sleep inhibited it, particularly R2 responses. REM sleep showed no significant difference from quiet wakefulness.
Impact:
- Provides normative data for blink reflex development in infants.
- Offers insights into maturation of trigeminal and facial nerve pathways.
- Highlights the impact of physiological state on early neurodevelopmental assessments.
Abstract:
The blink reflex was elicited in 42 awake and quiet children from birth to 3 years of age. The R1 ipsilateral reflex response was always recorded. Its latency decreased significantly during the first 6 months of life whereas the VIIth nerve motor conduction velocity increased markedly; its threshold stimulus was lower in children after 1 year of age. R2 responses, especially contralateral ones, were sometimes absent in infants under 9 months of age; beyond that age, they were constant and bilateral. The ipsilateral R2 latency response diminished during the first 6 months of life, and the R2 reflex threshold became lower in infants above 1 year of age. When elicited after crying, in 22 children, the reflex components were facilitated; R1 response occasionally appeared bilaterally, its amplitude increased and its threshold was lower. During REM sleep, in 12 children, the reflex responses were similar to those recorded during quiet wakefulness. On the contrary, non-REM sleep recorded in 12 children markedly depressed the reflex responses; this inhibition was more pronounced for R2 responses.