Developmental transformations of spontaneous movements in early infancy.

One component of the major transformation of neural functions at the end of the second postnatal month is concerned with a change in the appearance of general movements. These endogenously generated complex movements lose their writhing character and are replaced by a transient form, termed 'fidgety' movements. There are individual differences in the age of onset and duration as revealed by longitudinal observations. It is speculated that 'fidgety' movements may be related to a postnatal calibration of the proprioceptive system.