Fig. 1

A distinct GABAergic projection from ZIr to PAG. a Left three panels, co-localization of GFP (green) signal and NeuN (red) staining in the ZIr of a GAD67-GFP mouse. Scale: 200 µm. Right panel, percentage of GFP⁺ neurons in the rostral sector (ZIr) and more caudal part (ZIv/ZId) of ZI. b Injection of Cre-dependent GFP virus into ZIr of GAD2-Cre mice. Confocal images show GFP expression in the injection site (upper middle; scale: 500 µm) and in several target structures (upper right and lower; scale: 200 µm). Blue shows Nissl staining. ZIr zona incerta, rostral, PAG periaqueductal gray, SC superior colliculus, PRNr pontine reticular nucleus, rostral, RN red nucleus. c Injection of Cre-dependent GFP virus into ZIv/ZId of PV-Cre mice. Images show GFP expression in the injection site (upper middle; scale: 500 µm) and in several target structures (upper right and lower; scale: 200 µm). d Summary of target areas of GAD2⁺ ZIr (left panel) and PV⁺ ZIv/ZId (right panel) neurons. PO posterior complex of the thalamus, APN anterior pretectal nucleus, MRN midbrain reticular nucleus, MARN magnocellular reticular nucleus