Neurological development during toddling age in normal children and children at risk of developmental disorders.

Toddling age (1.5-4 years) is a period in which the quality rather than the quantity of motor functions changes. We examined 305 normal and 43 so called 'risk' children with an examination technique which concentrates on observations of motor functions (grasping, sitting, crawling, standing and walking) in a standardized free field situation. Examples of the changes during toddling age are presented such as the decrease of yoke movements (i.e. shoulder movements during reaching), the increase of trunk motility, of variability of speed during crawling, narrowing of gait width, and an increased ability to avoid objects on the floor and to show maneuverability during walking. All changes occurred in the normal children between the ages of 2 and 3 years. They reflect a 'transformation' of neural functions. Many of the 'risk' children show qualitatively different motor behaviour, which is interpreted as non-optimal and which can be an early sign of neurological impairment. The transformation in neural functions is discussed in terms of neuroanatomical changes during toddling age.