Posture In The Picture: On The Relevance Of Postural Control In Children With Developmental Motor Disorders

Deficient postural control is a main factor in motor disorders such as cerebral palsy (CP) and developmental coordination disorder (DCD)--disorders which from early childhood seriously interfere with the quality of life. The abnormalities in postural control might be due to deviations in the early development of the CNS or to insults in the preand perinatal period, leading to deficiencies in the processing of sensory information and motor output. Recent research has pointed to the considerable compensational capacity of the CNS and possibilities for adaptation at young stages. In the summer of 2004 a workshop was organized in Groningen, the Netherlands in which leading experts on research into sensory systems, motor circuitries and sensori-motor coordination involved in movement and postural control, discussed their recent research findings and their views on motor development. The workshop aimed at covering these fields from neurobiological, neurobehavioral, and clinical perspectives, the latter including the consequences for therapeutic management of children with developmental motor disorders. In the first section on theoretical issues and postural development, Albert Gramsbergen discusses postural control and extremity movements from an evolutionary perspective and he particularly focuses on the evolution of the motor systems in the CNS. Bert Otten presents a computer model of an articulated threesegment limb, controlled by pairs of muscles which is requested to follow a certain trajectory and he questions whether movements are planned in terms of endpoint equilibrium positions of the limb, or whether the CNS plans movements by selecting appropriate sets of muscle activations with certain durations to move a limb from one point to the other. Mark Latash discusses his Uncontrolled Manifold (UCM) hypothesis, based on the assumption that the CNS organizes covariation of elemental variables to stabilize important performance variables in a task-specific manner. This allows the formulation of testable hypotheses with respect to the development of postural synergies in both typically and atypically developing persons. Mijna Hadders-Algra reviews the development of postural control during infancy. Two functional levels can be distinguished, a basic level dealing with the generation of direction specific adjustments and a second level, involved in adaptations of the direction specific adjustments. Development probably starts with an innate repertoire of direction specific adjustments. From 6 months onward, the second level of postural control becomes functionally active. Christine Assaiante, reviews earlier studies on the development of postural control during walking, and her message is that children initially build a repertoire of postural strategies, while in a second phase they learn to select the most appropriate strategy in the given circumstances. Her own research showed that anticipatory postural control, despite its relatively early onset only matures slowly during childhood. In the second session on the development of the motor systems involved in postural control, Laurent Vinay reviews recent literature on brain stem pathways involved in postural control. He particularly focuses on serotonergic pathways in the rat and he extrapolates the results of experimental research to human development. Jos IJkema Paassen reviews literature on the properties of muscles with specific postural tasks as well as the development of their innervation. Most of the data were obtained in animal investigations but she makes attempts to extrapolate these data to the developing human. Jerome Swinny discusses his own research into cerebellar development and that of others, particularly on the development of the two afferent