April 2020
Vol 6, Issue 15

About The Cover

Cover image expansion

ONLINE COVER When we sleep, we lose our ability to respond to the environment. When a stimulus occurs that would normally attract our attention, like quiet music playing or birds chirping outside the window, we don't notice or react. However, scientists have not fully understood how sleep is maintained despite ongoing external sensory events, nor how processes in the brain determine whether we will awake from a sensory cue in our surroundings. To test whether reduced locus-coeruleus norepinephrine (LC-NE) activity mediates unresponsiveness during sleep—and whether heightened LC-NE activity leads to sensory-evoked awakenings—Hanna Hayat et al. monitored the brain activity of slumbering rats provided with sensory cues. They gained insights using a combination of LC single-neuron electrophysiology, behavioral, pharmacological, and optogenetic techniques. The researchers provide evidence that the level of LC-NE activity during sleep does, in fact, determine how likely a sleeper is to awake due to sensory stimulation. The findings could help scientists better understand both sleep and neuropsychiatric disorders, as well as the effects of anesthesia. [CREDIT: ANA YAEL]