Neuronal IL-4R deficiency has no effects on dendrite morphology, PSC amplitudes, and Morris water maze. Analysis of biocytin-filled patched CA1 neurons of P30 il4ra^fl/fl.Syn cre mice (cre⁻n = 5, cre⁺n = 4, littermates, pooled data from two independent experiments). (A and B) Sholl analysis reveals no differences in number of Sholl intersections, nor in (B) dendritic length, branch points, or terminal points. (C and D) Spine analysis shows no significant difference in spine density, nor in (D) spine morphology. (E) Exemplary images of spines of secondary dendrite of cre⁺ and cre⁻ mice. Scale bar = 2 µm. (F) Amplitudes of mEPSCs, mIPSCs, and sPSCs were unchanged in il4ra^fl/fl.Syn cre mice (9–10 neurons from at least three littermates per genotype, representative data from two independent experiments). (G) Amplitudes of mEPSCs and mIPSCs were unchanged after treatment with IL-4 (10–14 neurons from at least three mice per treatment, representative data from two independent experiments). (H–L) In vivo recordings of LFPs in mPFC (two independent experiments) show an increase in θ and low γ waves in il4ra.^fl/fl.Syn cre⁺ mice compared with cre⁻ littermates (n = 5 each, male, 12- to 16-wk-old), accompanied by increased (K) number of units firing and (L) firing rate. (M) Morris water maze (MWM) test (two independent experiments) showed no difference in learning between cre⁺ and cre⁻ littermates. (N) Mice spend equal times in the target zone at final test in MWM. (O) Representative graphs of swimming patterns at target test. Plots (B–D, F, G, and I–N) depict mean ± SEM. Statistics: (A, D, H, and M) two-way ANOVA, * P < 0.05; (B–C, F–G, I–L, and N) Bayesian analysis, accuracy, * >80%, ** >90%, *** >95% (see Data S1).