Whole-brain monosynaptic afferents to the sublaterodorsal tegmental nucleus GABAergic neurons in mice

The sublaterodorsal tegmental nucleus (SLD) is a critical hub for regulating REM sleep and muscle atonia, with its dysfunction linked to disorders such as REM sleep behavior disorder (RBD) and cataplexy. However, the presynaptic patterns influencing SLD GABAergic neurons—one of the primary neuronal subtypes within the SLD—remain poorly understood. Here, we employed a modified rabies virus in conjunction with a Cre/loxP gene-expression strategy to systematically map and quantify the whole-brain monosynaptic afferents to SLD GABAergic neurons in mice. We identified 139 distinct brain nuclei targeting these neurons, with the majority of inputs originating from the midbrain, pons, and medulla, and 67.99% of the input neurons originating ipsilaterally and 32.01% contralaterally. Notably, the mesencephalic reticular nucleus, superior colliculus, oral part of the pontine reticular nucleus, gigantocellular reticular nucleus, lateral hypothalamic area, and zona incerta were found to be the primary sources of input to SLD GABAergic neurons. Additionally, certain input nuclei displayed a contralateral dominance in their projections to SLD GABAergic neurons. Immunofluorescence staining further revealed that input neurons expressed a variety of neuronal markers associated with important physiological behaviors. These findings provide a relatively comprehensive anatomical insights into the integration of diverse information by SLD GABAergic neurons, shedding light on their roles in regulating complex physiological functions, and offer new avenues for exploring their functional contributions to sleep and motor control.