Sleep improves sequential motor learning and performance in patients with prefrontal lobe lesions

Objectives Motor skill learning involves both practice and a latent, sleep-dependent process of consolidation that develops after training (“off-line” learning). Sleep consolidation is linked to reduced brain activation in prefrontal areas, along with strong involvement of parietal regions. The objective in this study was to investigate the influence of sleep on the consolidation process of a motor task in patients with prefrontal damage. Patients and methods For that purpose 14 patients with acquired focal prefrontal lesions, 15 age-matched healthy controls, and five patients with parietal lesions were evaluated on a serial reaction time task, SRTT, before and after a night of monitored sleep. Verbal and working memory was also tested. We anticipated that patients with prefrontal lesions, who are impaired in the acquisition of motor tasks, would benefit greater from sleep than the other two groups, since consolidation does not depend on prefrontal regions. Results Prefrontal patients showed an erratic learning curve at night, with great inter- and intrasubject variability that normalized after sleep. They also showed higher overnight learning of the motor skill and improvement on speed performance on the SRTT. No differences in the other memory tests were found between sessions. Conclusion Prefrontal-injured patients benefit from night sleep in terms of motor task learning and performance, likely related to an advantageous off-line learning. Sleep could play a role in motor rehabilitation programs in prefrontal patients.