Networks associated with short-term motor learning of chopstick-use skills with the non-dominant hand in older adults

<p> [Introduction] This study aimed to determine the offline brain networks associated with short-term motor learning of chopstick use with the non-dominant hand in older adults in comparison with younger adults. [Methods] This study included 20 healthy older and 20 younger adults, all right-handed. The participants practiced picking up objects and moving them from left to right using chopsticks with their left hand for 9 min. Chopstick-use skills and resting-state functional connectivity (RSFC) were measured pre- and post-practice, and the measurements were used for pre- and post-practice comparisons for each group and between the two groups. Furthermore, the correlation between chopstick-use skills and RSFC was investigated. Chopstick-use skills were assessed by measuring the number of times the participants moved objects from a plate on the table to their mouth using chopsticks with their left hand within a 30-s period. RSFC data were obtained by scanning functional brain images resting state with functional MRI and then extracting Z-scores between the right primary motor cortex (M1) and regions of interest (the right and left postcentral gyrus, superior parietal lobule, supramarginal gyrus, angular gyrus, cerebellar lobule IV/V, VI, VIII, the right cerebellar crus I, the left cerebellar crus II). Next, the networks wherein RSFC significantly changed post-practice were identified for each group. Finally, the correlation between the RSFCs of the identified networks and chopstick-use skills were examined. [Results] Chopstick-use skills significantly improved in both groups post-practice. In older group, the RSFC between the right M1 and the left angular gyrus significantly increased post-practice, as did the RSFC between the right M1 and the left cerebellar crus II in younger group. These RSFCs were also significantly positively correlated with chopstick-use skills in terms of the amount of change pre- and post-practice. In addition, the RSFC between the right M1 and the left supramarginal gyrus increased post-practice in the younger group. [Conclusion] The results indicate that enhancement of neural connections between the right M1 and the left angular gyrus in the older group and between the right M1 as well as the left cerebellar crus II, the left supramarginal gyrus in the younger group may have contributed to the improvement of chopstick-use skills during the early stages of chopstick-use learning with the left hand. The results suggest that different resting-state networks are involved in motor learning for the older and younger groups. This study may provide a basis for comparison with further studies of patients with stroke of different ages to understand compensatory networks.</p>