Precocious cardiac orienting in a human anencephalic infant.

An anencephalic infant, 3 to 6 weeks old, responded to acoustic stimulation with cardiac decelerations typical of the response pattern seen in normal, older infants. Such precocity implies unexpected competence of lower brain structures and suggests that, in the normal infant, feedback from immature higher centers may sometimes interfere with rather than modulate the functioning of lower centers.