Laterality of arm movement in full-term newborn.

We have investigated 20 healthy full-term newborns between the 4th and the 6th day of life in standard conditions for laterality of arm movements, before and after introduction of a target. The durations of recording were: (a) 5 min continuously before target introduction; (b) five 1-min units during target presentation. The movements studied were extension, flexion, movement with semiflexed arm with hand half-open or open toward the midline of the body, and total movements. Each of these items were counted separately and the counts were compared within and between sides. Spontaneous movements showed no side preference whereas in the presence of the target, movements toward the midline (target directed movements) showed a significant right-hand preference.

Upper limb movements in the emergence of object cognition.

Previous studies showed that 40% of fullterm newborns with "anterior plane hypotonia" (APH) neuromotor anomaly present retarded development of object cognition. To understand the possible motor dynamics of this retardation, we studied the principal upper limb movements in a group of normal newborns and in one of APH newborns, with and without stimulus. The total quantity of movement proved to be similar in the two groups but there were differences in the frequencies of the various types of movement, to the detriment in the APH subjects of the movements considered most relevant to object relations. These data underline the importance of the qualitative integrity of newborn movement to the emergence of object cognition.