“…Using cell-type-specific retrograde trans-synaptic rabies virus tracing techniques, we found that RMTg GABAergic neurons receive wide projections in the brain, including dense projections from the LH, zona incerta, and LHb. Moreover, several brain regions, such as the PAG, DR, and LC, which contain a large number of REM-off neurons, also send inputs to RMTg GABAergic neurons 3 , 78 , 79 . Therefore, more research is needed on which emotional or physiological factors or which input circuit is implicated in the activation of RMTg GABAergic neurons to regulate sleep.…”