Microglia control GABA _A R plasticity and fluctuations of CaMKII phosphorylation across the light/dark cycle. (a) Left: Confocal images of L1 total CaMKII immunoreactivity showing no changes between ZT18 and ZT6 in transgenic control mice (tCTL). Scale bars, 20 µm. Right: Mean intensity of total CaMKII signal normalized to ZT18. No statistical significance by nested two-tailed t test. n = 40–50 FOVs from four to five mice per group. (b) Confocal images of L5 Thr286-phosphorylated CaMKII immunoreactivity. Scale bars, 20 µm. Right: Mean intensity of Thr286-phosphorylated CaMKII signal normalized to ZT18. No statistical significance by nested two-tailed t test. n = 32 to 40 FOVs from four to five mice per group. (c) Mean intensity of Thr286-phosphorylated CaMKII signal in L1 normalized to ZT18. n = 49 to 50 FOVs from 5 mice per group. *P < 0.05, nested two-tailed t test. (d) Left: Fraction of gephyrin⁺VGAT⁺ synapses colocalized to GABA_AR cluster. Right: Mean intensity of GABA_AR clusters at extrasynaptic sites. n = 48 to 65 FOVs from four to five mice per group. *P < 0.05, nested two-tailed t test. (a–d) Results are presented as minimum to maximum box-plots.