Sleep-dependent learning and motor-skill complexity

  1. Kenichi Kuriyama1,2,
  2. Robert Stickgold1, and
  3. Matthew P. Walker1,3,4
  1. 1Center for Sleep and Cognition, Department of Psychiatry, Harvard Medical School, Beth Israel Deaconess Medical Center, Boston Massachusetts 02215, USA 2Department of Psychophysiology, National Institute of Mental Health, National Center of Neurology and Psychiatry, Kohnodai, Ichikawa 272-0827, Japan3 Sleep and Neuroimaging Laboratory, Department of Psychiatry, Harvard Medical School, Beth Israel Deaconess Medical Center, Boston Massachusetts 02215, USA

Abstract

Learning of a procedural motor-skill task is known to progress through a series of unique memory stages. Performance initially improves during training, and continues to improve, without further rehearsal, across subsequent periods of sleep. Here, we investigate how this delayed sleep-dependent learning is affected when the task characteristics are varied across several degrees of difficulty, and whether this improvement differentially enhances individual transitions of the motor-sequence pattern being learned. We report that subjects show similar overnight improvements in speed whether learning a five-element unimanual sequence (17.7% improvement), a nine-element unimanual sequence (20.2%), or a five-element bimanual sequence (17.5%), but show markedly increased overnight improvement (28.9%) with a nine-element bimanual sequence. In addition, individual transitions within the motor-sequence pattern that appeared most difficult at the end of training showed a significant 17.8% increase in speed overnight, whereas those transitions that were performed most rapidly at the end of training showed only a non-significant 1.4% improvement. Together, these findings suggest that the sleep-dependent learning process selectively provides maximum benefit to motor-skill procedures that proved to be most difficult prior to sleep.

Footnotes

  • Article and publication are at http://www.learnmem.org/cgi/doi/10.1101/lm.76304.

    • Accepted September 8, 2004.
    • Received March 1, 2004.
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