Figure 5

In vivo measurement of orexin neuron activity using fiber photometry.

(A–C) Schematic drawings showing the apparatus for in vivo fiber photometry. (A) Overall view of the fiber photometry system. (B) Detail of the optical arrangement of the fiber photometry system. (B) is an enlarged image of the circled area in (A). (C) Optical measurement of the change in intracellular calcium concentration from G-CaMP6-expressing orexin neurons. (D) Confirmation of the fiber tract after fluorescent measurements. Coronal section of the brain from an orexin-tTA mouse injected with AAV-TetO(3G) G-CaMP6. The dashed line indicates the location of the inserted fiber. The right panel is a magnified image of the boxed region in the left panel. (E) Confirmation of G-CaMP6-derived green fluorescence (500–550 nm) originating from orexin neurons of head-fixed mice. The spectrum of fluorescence was measured at intervals 1 mm in depth from the surface of the brain. G-CaMP6-derived green fluorescence (500–550 nm, green bar) was increased at a depth of 5 mm where orexin neurons were densely distributed. (F) Fluorescence intensity at each depth is summarized as the Area Under the Curve (AUC).