Circadian rhythms of PER2::LUC expression continue in the presence of TTX. (A) Representative example of total bioluminescence integrated across delineated DMH, Arc, ependymal cell layer (Ep), ME/PT and VMH in an intact MBH slice culture imaged on an EM-CCD camera. All areas except the VMH are initially rhythmic in control medium. After 2 days, the slice was treated with 0.5 μM TTX for 3 days before return to control medium, grey shading represents TTX in the culture medium. All previously rhythmic areas sustained rhythmicity in the presence of TTX. (B) EM-CCD image showing PER2::LUC bioluminescence expression in an MBH cultured with 0.5 μM TTX. Single cells can be discriminated in the DMH (inset) and Arc. Calibration bar 250 μm. (C) Plots showing integrated bioluminescence for representative individual cells in DMHc, ArcD (dark blue) and ArcL (light blue). Individual cellular rhythms continue in the presence of TTX.