Neural mechanisms associated with sleep-dependent enhancement of motor learning after brain injury

This study aimed to examine the improvement in performance and functional magnetic resonance imaging correlates of motor learning after a daytime nap versus a period of resting wakefulness among individuals with traumatic brain injury. A sample of 32 individuals with traumatic brain injury was randomly assigned to a Sleep (N = 17) or Wake (N = 15) group after a period of training on a motor sequential learning task. A 45-min nap opportunity was provided for the Sleep group, while the Wake group watched a documentary for 45 min. Performance at the end of training was compared with their performance after the nap or wake intervention. Before and after the intervention, the motor sequential learning task was completed in the magnetic resonance imaging scanner to examine the relationship between change in performance and neural activation. Participants in the Sleep group showed significant gains from the end of training to after the intervention, whereas the Wake group did not. The functional magnetic resonance imaging results showed that relative to the Wake group, the Sleep group showed significantly decreased activation post-intervention in the anterior cingulate/paracingulate, cerebellum, cuneus/precuneus, and inferior parietal lobule including angular and supramarginal gyri. Importantly, across both groups, increased task performance at post-intervention was associated with decreased activation in the anterior cingulate/paracingulate and cerebellum. This study demonstrated the enhancing effect of a nap on motor learning performance in a sample of individuals with traumatic brain injury, with patterns of neural activation suggesting that the sequence was more automatized in the Sleep group. Strategic placement of a nap after an intense period of motor learning in the medical rehabilitation setting may have important implications for maximizing recovery after traumatic brain injury.