Figure 1.

Schematic of the experimental approach. A, Imaging apparatus. The experimental animal is head-fixed and able to run or rest on a standard spherical treadmill that sits in a custom laser-cut three-piece acrylic chamber that consists of a cube, open at the top, with a two-piece lid that contains an aperture to accommodate the microscope objective. B, Breeding strategy used to produce Scn1a+/− mice and age-matched wild-type littermate controls expressing tdTomato in PV-positive GABAergic INs. PV-Cre mice on a C57 background (C57.PV-Cre) were crossed to the Ai14D reporter strain (LSL-tdTomato; also on a C57 background) to produce PV-Cre.tdTomato double heterozygous mice. PV-Cre.tdTomato double heterozygous females were then crossed to Scn1a+/− males on a 129.S6 background (129.Scn1a+/−) to produce triple transgenic Scn1a+/− mice (Scn1a.PV-Cre.tdT) and wild-type littermates. C, Labeling of PV-INs for in vivo 2P calcium imaging in Scn1a.PV-Cre.tdT mice during seizure induction. Shown is GCaMP6f labeling of neurons in layer 2/3 sensorimotor cortex (green) including PV-INs (red) in an Scn1a.PV-Cre.tdT mouse. The image is an average of 10 frames of 512 × 512 pixels acquired at 29.4 Hz at 2× digital zoom. Scale bar, 50 μm.