Enduring motor memory of walking on a split-belt treadmill in young children and adults

Background Adults and children modify their motor program to accommodate persistent changes in movement conditions, called motor adaptation. We studied motor adaptation using a split-belt treadmill, with the belts for each leg at different speeds. A memory trace is reflected when reintroduction of the previously novel condition results in a smaller initial error in comparison to the first exposure. To date, retention of motor adaptation on a split-belt treadmill is only known for a 24 hour period. Research question We wondered if retention of split-belt adaptation extends over days and weeks, and whether it varies as a function of age. Methods We studied the persistence of the memory trace over 24 hours, one week, and two weeks, in young children (3-6 yr old), younger adults (20-30 yr old) and older adults (50-70 yr old). Results We found that retention of the memory trace declines with the interval duration, but was evident up to 2 weeks after initial exposure in all age groups. Retention of the motor memory in children and younger adults was better than older adults. Further, only older adults demonstrated forgetting between trials on a single day when a short break was introduced, but this forgetting was diminished with repeated trials. Significance The results indicate that long term memory of motor adaptation is affected by age, but it may be possible to enhance the memory in older adults by repeated exposure. For clinical practice, this may mean that older adults need more repetition when learning walking-related motor skills. ### Competing Interest Statement The authors have declared no competing interest.