Electrically elicited blink reflex in normal neonates.

The electrically elicited blink reflex was tested in 30 full-term neonates. Of the two distinctly separate responses, early component R1 and late component R2, R1 was recorded in all but three infants. Its latency, 12.1+/-1.0 msec (mean+/-SD), was significantly greater than that in adults (10.6+/-0.8 msec) despite a considerably shorter length of the reflex arc in infants. Unlike the response in adults, R2 was elicited in only 20 of 30 infants, mostly on the side ipsilateral to the stimulus. The reduction of reflex excitability of R2 in neonates must occur primarily at the level of interneurons since oligosynaptic R1 was elicited with ease whereas polysynaptic R2 was not.