A matter of time: rapid motor memory stabilization in childhood.

Are children better than adults in acquiring new skills ('how-to' knowledge) because of a difference in skill memory consolidation? Here we tested the proposal that, as opposed to adults, children's memories for newly acquired skills are immune to interference by subsequent experience. The establishment of long-term memory for a trained movement sequence in adults requires a phase of memory consolidation. This results in substantial delayed, 'offline', performance gains, which nevertheless remain susceptible to interference by subsequent competing motor experience for several hours after training, unless sleep is afforded in the interval. Here we compared the gains attained overnight (delayed gains) by 9-year-olds and adults after training on a novel finger-to-thumb movement sequence, with and without subsequent interference by repeating a different movement sequence. Our results show that, in 9-year-olds, but not in adults, an interval of 15 min. between the training session and interfering experience sufficed to ensure the expression of delayed, consolidation phase, gains. Nevertheless, in the 9-year-olds, as well as in adults, the gains attained with no interference were significantly larger. Altogether, our results show that while the behavioral expressions of childhood and adult consolidation processes are similar, procedural memory stabilizes, in the waking state, at a much faster rate in children. We propose that, in children, rapid stabilization is a mechanism whereby the constraints on consolidating new experiences into long-term procedural memory are relaxed at the cost of selectivity.