Autism-associated neuroligin-3 deficiency in medial septum causes social deficits and sleep loss in mice

Patients with autism spectrum disorder (ASD) frequently experience sleep disturbance. Genetic mutations in Neuroligin-3 (NLG3) genes are highly correlative with ASD and sleep disturbance. However, the cellular and neural circuit bases of this correlation remain elusive. Here, we find the conditional knockout of NLG3 (NLG3-CKO) in the medial septum (MS) impairs social memory and reduces sleep. NLG3 knockout in MS causes hyperactivity of MS-GABA neurons during social avoidance and wakefulness. Activation of MSGABA neurons induces social memory deficits and sleep loss in C57BL/6 mice. In contrast, inactivation of these neurons ameliorates social memory deficits and sleep loss in NLG3-CKO mice. Sleep deprivation leads to social memory deficits, while social isolation causes sleep loss, both resulting in a reduction of NLG3 expression and an increase in activity of GABAergic neurons in MS from C57BL/6 mice. Furthermore, MS-GABA-innervated CA2 neurons specifically regulate social memory without impacting sleep, whereas MSGABA-innervating neurons in the preoptic area selectively control sleep without affecting social behavior. Together, these findings demonstrate that the hyperactive MS-GABA neurons impair social memory and disrupt sleep resulting from NLG3 knockout in MS, and achieve the modality specificity through their divergent downstream targets.