Movement-related brain potentials during hand squeezing in children and adults

Motor readiness potentials (MRPs) during hand squeezing were recorded from scalp leads in a group of right-handed and left-handed children and adults in order to determine: (1) the relationship of the MRP to age and motor control, measured by eye movement, (2) MRP hemispheric differences during both unilateral and bilateral movements and, (3) the relationship between different MRP components. MRP components before the response were independent of those after the squeeze. MRP positivity decreased with age for all squeezes. Motor control, which increased with age, related to MRP polarity in different leads depending on the responding hand. Dominant squeezes showed the greatest MRP positivity followed by non-dominant and bilateral squeezes. Motor control followed an inverse order across tasks; as motor control increased, positivity decreased. There were no asymmetries of the MRP until squeeze onset. Asymmetry occurred only during right hand squeezes regardless of handedness.