Trained location-specific activity changes during sleep after training of a visual task

Abstract

Title: Trained location-specific activity changes during sleep after training of a visual task (88 words, including spaces) Authors: Yuka Sasaki*,1,4,5, Yuko Yotsumoto*,1,2,5, Patrick Chan1,2, Chris Vasios1,5, Giorgio Bonmassar 1,5, José Náñez3, Shinsuke Shimojo4, Takeo Watanabe2. 1. Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital. 149 13th Street, Charlestown, MA 02129, USA. Tel: [phone] Fax: [phone]. Department of Psychology, Boston University. 64 Cummington Street, Boston, MA 02215, USA. Tel: [phone] Fax: [phone]. Department of Social and Behavioral Sciences, Arizona State University. Phoenix, Arizona 85069-7100, USA. 4. ERATO Shimojo Implicit Brain Function Project California Institute of Technology Pasadena, CA 91125, USA 5. Department of Radiology, Harvard Medical School 25 Shattuck Street, Boston MA 02115, USA * Equal contribution Corresponding authors: Takeo Watanabe ([e-mail]) and Yuka Sasaki ([e-mail]) Abstract: A central interest of neuroscience is the role of sleep in strengthening, or consolidating, learning. However, this role is still highly controversial and, if any, the underlying neural mechanism remains unclear. We conducted experiments in which blood oxygen level dependent (BOLD) signals by functional magnetic resonance imaging (fMRI), indication of neural activity, were measured while the subjects are asleep. A texture discrimination task (TDT) training methodology (Karni & Sagi, 1991) was used. Recently developed important technologies were used to simultaneously measure BOLD signals, electroencephalogram (EEG), electrooculogram and electromyogram for polysomnography while the subject was asleep. This technology allowed us to objectively determine whether the subject is in sleep or awake and also in which sleep stage the subject is, using the most standard criteria in sleep research. Activity enhancement was obtained only in the trained part of V1 during sleep after training of a visual learning task, which was objectively identified as NREM sleep by a new technique in which polysomnogram was measured concurrently with fMRI. The amount of enhancement showed a significant positive correlation with performance increase after sleep. The results provide direct and strong evidence that during sleep consolidation of learning occurs only in local circuits directly related to the learning task.