A growing body of evidence suggests that sleep plays an important role in strengthening what is learned before sleep and making the learning persist for a long time. This is called consolidation. Although consolidation in sleep is a key function in learning, the detailed mechanism is not clear. In this project, Dr. Yuka Sasaki of the Massachusetts General Hospital aims to clarify consolidation in sleep by combining cutting-edge brain imaging technologies such as magnetic resonance imaging (MRI), electroencephalography (EEG), magnetoencephalography (MEG), and functional MRI (fMRI). Particularly, the focus of the project is on examining the mechanism for sleep consolidation of learning of a visual task (perceptual learning) that is known to be associated with changes in a highly localized region in the visual cerebral cortex. Researchers are measuring spatio-temporal activation changes in the localized region during the initial period of sleep (non-REM sleep) after training on the visual task. Brain activity with high spatial resolution is obtained using MRI along with high temporal resolution brain signals obtained with EEG and MEG. By combining these signals with both temporally and spatially high resolution, the detailed mechanisms of sleep consolidation are being clarified. How such brain activity changes during sleep is related to improvement in performance on the visual task (the amount of perceptual learning) is being examined. The results from this project will contribute to a deeper understanding of the mechanism of sleep consolidation of perceptual learning.
This project provides rare opportunities of training and educating undergraduate and graduate students. Students learn cutting-edge neuroimaging techniques, such as the use of multimodal combinations of EEG/MEG/MRI, as well as functional MRI technique applied to retinotopic mapping. They also learn the theoretical backgrounds of the techniques. In addition, students learn how to analyze behavioral data through psychophysical experiments. Moreover, understanding of the consolidation process of memory and learning during sleep can help to improve education, by informing us how what is learned can be more efficiently and firmly memorized. In addition, therapeutic methods can be developed to eliminate or weaken bad and undesirable memory and learned habits, including traumatic memories, smoking, and obsessive behaviors.
