Figure 1.

A schematic diagram of the neural circuitry involving LPO and VTA cells. NREM sleep is induced by subpopulations of GABAergic LPO neurons through inhibition of wake-promoting regions. To maintain continuous NREM sleep, we hypothesize that GABAergic LPO neurons inhibit the activity of local wake-promoting glutamatergic LPO cells. Further, we propose that wake-promoting GABAergic LPO cells inhibit NREM-promoting GABAergic VTA cells to promote transitions from NREM to wakefulness. Wakefulness may be further facilitated by excitation of wake-promoting glutamate/dopamine VTA neurons by glutamatergic LPO cells.