A common thalamic hub for general and defensive arousal control

The expression of defensive responses to alerting sensory cues requires both general arousal and a specific arousal state associated with defensive emotions. However, it remains unclear whether these two forms of arousal can be regulated by common brain regions. We discovered that the medial sector of the auditory thalamus (ATm) in mice is a thalamic hub controlling both general and defensive arousal. The spontaneous activity of VGluT2-expressing ATm (ATm(VGluT2+)) neurons was correlated with and causally contributed to wakefulness. In sleeping mice, sustained ATm(VGluT2+) population responses were predictive of sensory induced arousal, the likelihood of which was markedly decreased by inhibiting ATm(VGluT2+) neurons or multiple downstream pathways. In awake mice, ATm(VGluT2+) activation led to heightened arousal accompanied by excessive anxiety and avoidance behavior. Notably, blocking their neurotransmission abolished alerting stimuli-induced defensive behaviors. These findings may shed light on the comorbidity of sleep disturbances and abnormal sensory sensitivity in specific brain disorders.

Automated summary

This study explores the role of the medial sector of the auditory thalamus (ATm) in controlling general and defensive arousal in mice. The activity of ATm(VGluT2+) neurons is correlated with wakefulness and contributes to sensory-induced arousal. Inhibiting ATm(VGluT2+) neurons or downstream pathways reduces the likelihood of sensory-induced arousal in sleeping mice. Activation of ATm(VGluT2+) leads to heightened arousal, accompanied by anxiety and avoidance behavior in awake mice. Blocking neurotransmission in ATm(VGluT2+) neurons eliminates alerting stimuli-induced defensive behaviors. These findings may have implications for understanding sleep disturbances and abnormal sensory sensitivity in specific brain disorders.