Frontier Research Institute for Interdisciplinary Sciences
Tohoku University

Sleep is one of the instinctive behavior. Mammals have two stages of sleep, i.e., rapid eye movement (REM) sleep and non-REM sleep, which show completely different brain activities. Although no one can live without sleep, physiological function of sleep is one of the mystery-shrouded issue in the field of brain science so far. To investigate this, I have started to elucidate the regulatory mechanism of sleep/wakefulness using mice.

First, I introduced optogenetics technique to identify the neural network which regulates sleep/wakefulness. Optogenetics enables us to manipulate specific type of neural activity at high temporal resolution (See figure). Using this, I have revealed that inhibition of orexin neural activities in lateral hypothalamus induces the transition from wakefulness to non-REM sleep. In addition, activation of melanin-concentrating hormone neural activities can cause transition from non-REM sleep to REM sleep (Tsunematsu et al., J Neurosci 2011 and 2014).

Next, I recorded multiple neural activities from pons, cortex and hippocampus using silicon probe with 32 channels in unanesthetized mice. I focused on information processing during non-REM sleep and REM sleep, especially the relationship firing pattern and synchronization of neural activities.

With various experimental techniques I have learnt and knowledge I have gained in the past, I am excited to further explore, and thus unravel the mystery of sleep.