Electrophysiology of skilled performances in children.

Skilled performance is a result of appropriate integration of sensorimotor, cognitive and motivational functions. When Piaget was asked about the nature of reality and our knowledge of it, he answered: "I know an object only when I can act on it; before this action I cannot say anything about it". It has been proposed that motor actions are the source from which mental operations emerge. The intellectual growth of a child goes through stages during which actions, perceptions and ability for concrete or abstract thought hold in turn a predominant role. On the grounds of this theoretical framework it could be argued that neuropsychophysiological investigations of skilled performance in children which incorporate the study of performance-related brain electrical activity could contribute unique information with theoretical and clinical implications. A pattern of slow and phasic brain electrical activity is consistently associated with the execution of skilled ballistic tasks. The slow potentials of the preparatory period (Bereitschfts Potential-BP) are of low amplitude in low demand tasks and in young children. The potentials closely associated with the execution of the act and reflecting sensory feedback activity (Motor Cortex Potential-MCP) are constantly present in children of all ages. The potential associated with knowledge of results (Skilled Performance Positivity-SPP) is only present if task relevant exteroceptive information is expected and occurs. The SPP is independent of the action itself and of the existence of non-informative exteroceptive stimulation. The SPP is absent in unskilled tasks and in young children. The motor performance related with the execution of the motor act improves with increasing age.(ABSTRACT TRUNCATED AT 250 WORDS)