Zona incerta subpopulations differentially encode and modulate anxiety.

Despite recent clinical observations linking the zona incerta (ZI) to anxiety, little is known about whether and how the ZI processes anxiety. Here, we subject mice to anxious experiences and observe an increase in ZI c-fos­labeled neurons and single-cell calcium activity as well as an efficient effect of ZI infusion of diazepam, a classical anxiolytic drug. We further identify that somatostatin (SOM)­, calretinin (CR)­, and vesicular glutamate transporter-2 (Vglut2)­expressing cells display unique electrophysiological profiles; however, they similarly respond to anxiety-provoking stimuli and to diazepam. Optogenetic manipulations reveal that each of these ZI neuronal populations triggers specific anxiety-related behavioral phenotypes. Activation of SOM-expressing neurons induced anxiety, while photoactivation of CR-positive cells and photoinhibition of Vglut2-expressing neurons produce anxiolysis. Furthermore, activation of CR- and Vglut2-positive cells provokes rearing and jumps, respectively. Our findings provide the first experimental evidence that ZI subpopulations encode and modulate different components of anxiety.