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. 2017 Oct 19;171(3):507–521.e17. doi: 10.1016/j.cell.2017.08.050

Figure 1.

Figure 1

Inactivation of PV Interneurons Impairs Spatial Periodicity in Grid Cells

(A) Expression of hM4D-mCitrine in PV cells of the MEC (sagittal sections). Low-magnification image of entire MEC (left); high-magnification images from white frame in left panel (right). mCitrine-expressing cells in green (top), PV–expressing cells in red (middle), merge of mCitrine and SOM in yellow (bottom). Scale bars in left panel, 200 μm; right panel, 60 μm. Animal number is indicated at the top (for corresponding tetrode trace, see Figure S2). Note co-expression of mCitrine and PV (yellow, bottom frame).

(B) Representative MEC grid cell in a 1 m box from mouse with hM4D expression in PV interneurons (scale bar, 1 m). Location of cue card is indicated (stippled line atop). Subsequent figures all have the same size box and the same location of cue cards. Data were collected before CNO and both 30 min and 12 hr after. Top to bottom: color-coded firing rate maps (top, color bar indicates firing rate), spike locations overlaid on trajectory (middle, black on gray), and color-coded autocorrelograms (color bar, correlation from −1 to 1).

(C) Cumulative frequency diagrams showing significant decrease in grid score, spatial information, and spatial stability of grid cells 30 min after CNO-induced inactivation of PV interneurons, but not 12 hr later. Spatial stability is visualized as spatial correlation between rate maps at baseline and either 30 min or 12 hr after CNO.

(D) Cumulative frequency diagrams showing increase in mean firing rate outside, but not inside, grid fields after inactivation of PV interneurons.

(E) Cumulative frequency diagrams showing stronger decrease of grid scores in layer II than in layer III grid cells after CNO. See Figure S4 for absolute scores.

(F) Color-coded rate maps from grid cells in MEC layers II (left) and III (right) after CNO (six pairs of cells with approximately similar baseline grid scores in layers II and III). Peak rates (p) and grid scores (g) are indicated above each rate map. Animal and cell numbers are shown to the left.

See also Figures S1, S2, S3, S4, and S5.