Fig. 6: Effects of interneuron silencing via h4MDi on dentate granule cells.

a Schematic of the experiment (left) and example activity of a DG-GC recorded during multiple trials on the familiar track before (middle) and after (right) injection of clozapine in a mouse expressing inhibitory hM4Di receptors in DG PV-INs. b Average fraction of active cells (bars with continuous outline) and fraction of place cells (bars with dotted outline) in control (blue) and clozapine (orange) conditions in PV-h4MDi mice. Lines denote place-cell fractions in individual experiments. c Average calcium-transient rate of GCs with place fields on the familiar track (left group) or novel track (right group) in control (bsl) and clozapine (clz) conditions in PV-h4MDi mice. d Same as in c but for spatial information in PV-h4MDi mice. e–h Same as in a–d, but for mice where hM4Di was expressed in DG SOM-INs. See Supplementary Fig. 8 for the same experiment in CA1. i–k Same as in b–d, but for control PV-Cre and SOM-Cre animals in which INs were infected with the fluorescent protein mCherry. Injection of clozapine in these animals did not induce changes in GC activity. l Ratios of place cell transient rates after clozapine application divided by those under baseline conditions. Left, brown ensemble shows ratios for familiar context place cells in PV-Cre (left violin) and SOM-Cre (middle violin) animals injected with the active h4MDi construct. Ctr (right violin) shows data from control mice injected with the inactive viral construct. Right, yellow ensemble shows the same but for novel-context place cells. m Same as in l but showing ratios of spatial information after clozapine application divided by baseline values. c, d, g, h, j–m Thick lines represent median and interquartile ranges. Lines or dots, respectively, in the background indicate datapoints from individual GCs. b, c, f, g, I, j paired t-test, d, e, k Wilcoxon signed rank-sum test, l, m Kruskal–Wallis ANOVA on Ranks with Dunn’s post-hoc test. See the corresponding section of Supplementary Table 2 for a 2-way ANOVA testing for interactions between IN type and novelty. NS not significant, *p < 0.05; **p < 0.01, ***p < 0.001. All statistical tests are two-sided. For exact p values see Supplementary Table 2.