Interhemispheric relationships in 4- to 14-year-old children pointing to lateral targets.

Some developmental changes in movement control are not monotonic during childhood, which leads us to question how hemispheric relationships develop since they are closely involved with visuo-manual coordination. We tested right-handed children between 4 and 14 years of age performing pointing movements with the right and left hand towards visual targets located in the right and left hemifield. The analysis of movement parameters showed a left hand advantage in reaction time, but this is mainly due to the contralateral movements relative to the semifield of target presentation, suggesting that hemispheric asymmetry is not achieved even in older children. Interhemispheric transfer was evaluated through the difference between crossed (opposite hand and hemifield side) and uncrossed (same hand and hemifield side) movements. The difference was significant at all ages, and decreased with age between 4-6 and 7-9 years. It moved from early asymmetry in favor of the left-to-right interhemispheric transfer to adult-like symmetry at 10-14 years. The long development of hemispheric specificity and interhemispheric communication suggested by our results might be associated to asynchronous development of various processes involved in visuo-motor coordination, leading to qualitative changes in visually directed movement during childhood described in the literature.