THE EFFECT OF BEHAVIORAL STATE ON GENERAL MOVEMENTS IN HEALTHY FULL-TERM NEWBORNS - A POLYMYOGRAPHIC STUDY

In a group a eight healthy full-term newborns 6-h polygraphic recordin gs, which included EMG recording of eight arm muscles, were made to in vestigate the effect of behavioural state on general movement (GM) org anization. Simultaneous video recordings supplied information about th e form of the GMs. Additionally the effect of non-nutritive sucking du ring State 4 was evaluated. Behavioural state had a distinct effect on the makeup of GMs. GMs during State 4 displayed best the fluency and elegance which are characteristic of normal GMs. State-1-GMs were rare , had a short duration and sometimes had an abrupt onset. During State 2 GMs had a fragmented appearance. EMG differences between GMs in Sta te 2 and State 4 were demonstrated in burst duration (longer during St ate 2) and tonic background activity in the upper arm muscles (lower d uring State 2). Occasionally State-2-GMs had an abrupt onset. These ab rupt GMs were less often preceded by rapid eye movements and heart rat e changes than State-2-GMs with a gradual onset. GMs during State 5 we re abrupt anti vigorous and often had a high frequency tremor superimp osed. The EMGs of State-5-GMs revealed a shorter interval between the EMG bursts and a higher EMG burst amplitude in the upper arm muscles t han present during State-4-GMs. Non-nutritive sucking during State 4 i nduced a reduction of movement amplitude, a increase of EMG burst dura tion and an increase of tonic background activity in the biceps brachi i and the extensor carpi muscles.