Parvalbumin Neurons (PV) in the Basal Forebrain (BF) play pivotal roles in promoting wakefulness. Interestingly, BF PV neurons have dense projections to the Thalamic Reticular Nucleus (TRN) that is known to generate sleep spindles and protect Non-Rapid Eye Movement (NREM) sleep. However, the function of this anatomical connection in sleep-wake control is still unclear. We hypothesized that the BF PV neurons that project toward the TRN (PVBF?TRN) might modulate sleep and wakefulness. Intermittent optogenetic stimulation of these neurons with blue light at 8 Hz could modulate NREM sleep, including the continuity of NREM sleep, Slow Wave Activity (SWA), and Slow Wave Energy (SWE) in mice. This novel role of PVBF?TRN neurons was associated with increasing SWA or SWE, leaving the sleep spindle density unchanged. These findings suggest that the PVBF?TRN subpopulation among the BF PV neurons could operate as sleep-promoting neurons in addition to their well-known wake-promoting function, depending on their firing frequency and pattern. Altogether, this study may also provide important insights in developing novel therapeutics in sleep medicine, especially for patients suffering from major sleep disorders such as insomnia, as well as potential techniques for neurosurgery, though there are various challenges to overcome for clinical applications.

Sung-Jun Lee has earned his B.S. in February 2017 from Handong Global University at Pohang, South Korea. After graduation, he enrolled in M.S-PhD integrated course in March 2017 at Gwangju Institute of Science and Technology (GIST), located in Gwangju, South Korea. He is currently affiliated in the Translational Neuroscience Laboratory in the department of biomedical science and engineering as a PhD candidate. His primary research field involves basic neuroscience using animal models, including sleep disorders as well as neuropsychiatric disorders such as Autism Spectrum Disorder (ASD).