BzATP-induced GABA _A R synaptic enrichment. (a) Left: Cumulative fraction of GABA_ARα1 clusters’ intensities at gephyrin⁺ cluster. ****P < 0,0001, Kolmogorov–Smirnoff test. Middle: Mean intensity of extrasynaptic GABA_ARα1. Right: Fraction of gephyrin⁺ clusters colocalized to GABA_ARα1. No statistical significance by nested one-way ANOVA followed by Sidak’s multiple comparison test. n = 49 to 63 FOVs from five independent experiments. (b) Mean intensity of GABA_ARα1 clusters at gephyrin⁺ cluster. KN62, a CaMKII inhibitor, abolishes BzATP-induced synaptic upregulation of GABA_ARα1, indicative of a shared molecular mechanism at the neuronal level with iLTP. n = 53 to 57 FOVs from five independent experiments. *P < 0.05, nested one-way ANOVA followed by Sidak’s multiple comparison test. (c) BzATP has no effect on synaptic GABA_AR at putative L5. Left: Mean intensity of GABA_ARγ2 clusters at VGAT⁺ clusters. Right: Fraction of VGAT⁺ clusters colocalized to GABA_ARγ2 cluster. No statistical significance by nested two-tailed t test. n = 42 to 45 FOVs from six independent experiments. (a–c) Results are presented as a minimum to maximum box plots.