The idea that movements of the embryo begin before it is capable of responding to external stimulation as there are as yet no connections between motor and sensory neurons. Thus, the first movements of the embryo result solely from the autonomous discharge of motoneurons. The hypothesis gave rise to the notion of fixed action patterns in ethology and can be seen to be a forerunner of the central pattern generator in neurophysiology.
See Behavioral embryology, Central pattern generator (CPG), Fixed action pattern (FAP), Spontaneous motor activity