Researchers have established a causal link between the activity of a particular group of brain cells and transitions between sleep and wakefulness. Luis de Lecea and colleagues report their findings in Nature.
Hypocretin-producing neurons (Hcrt neurons) are located in a region known as the lateral hypothalamus, and are active during transitions from sleep to waking states. They are important for arousal stability, as their loss is linked to narcolepsy, a debilitating sleep disorder. Here the authors directly probe the impact of Hcrt neuron activity on the sleep state of mice, using optical stimulation to target Hcrt neurons genetically engineered to respond to light. They found that stimulating these cells increased the likelihood of transition from either slow wave sleep or rapid eye movement sleep to wakefulness, with higher frequencies reducing the length of time between the end of light stimulation and waking.
This is the first time that a direct link between the activity of Hcrt neurons and sleep-to-wake transitions has been confirmed. The authors suggest that because Hcrt deficiency results in arousal instability associated with narcolepsy, further insights into sleep disorders may result from their findings.
Luis de Lecea (Stanford University, Palo Alto, CA, USA)
Abstract available online.
(C) Nature press release.
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