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SUMMARY An electromyographic study of reflex responses elicited by stimulation of an area of skin in the lower limb was undertaken in awake or sleeping children from 3 days to 3 years of age. Recordings were made on the tibialis anterior and the short head of the femoral biceps. In the awake child, electrical stimulation of the cutaneous area around the toes evoked polysynaptic discharges (R II and R III) in both muscles. From birth to one year of age, the threshold for the tibialis anterior was much lower than for the short head of biceps, and the flexion reflex pattern predominated. reflexes during the first 3 years of life and assesses their variations with age and in different spontaneous states of waking and sleeping in order to consider the mechanisms which underlie and control medullary polysynaptic reflex activity. Our results should be compared with those published earlier'2 on the reduction of monosynaptic reflex activity during ontogenetic development and, at any age, during sleep. Subjects and methodsThe 55 healthy children (ranging from 3 days to 3 years of age) examined during this study were born at term and were free of neurological disorder. They may be divided into the following age-groups: 3 days to 3 months (n = 18), 3 months and one day to 10 months (n = 12), 10 months and one day to 20 months (n = 16) and 20 months and one day to 36 months (n = 9). The purpose of the procedures was explained and informed consent was obtained from a parent for each infant.Polysynaptic reflexes were studied in the lower limbs according to Hugon's method.56 They were evoked by cutaneous stimulation, using ring electrodes. The negative electrode was placed around the big toe and the positive electrode around the three small toes. Stimulation was produced by bursts of 5.1 ms rectangular electric shocks, separated by a 2 ms interval with a delay of at least 5 s between bursts, each burst being delivered when the muscles were relaxed (it is impossible to obtain constant and regular contractions from children). Recordings were taken using either bipolar surface electrodes or subcutane-531 by copyright.on 9 May 2018 by guest. Protected

The blink reflex was elicited in 50 children from birth to 3 years of age. In the awake state, the R1 response was always obtained; R2 responses, especially contralateral ones, were more difficult to elicit under 9 months of age. R1 latency and VIIth motor nerve conduction variations were a good witness of the peripheral nervous system maturation. The influence of the different states of waking and sleeping on these reflex responses was studied. These results and some of the mechanisms that underlie these changes are discussed.