Fig. 1

LiCl treatment restores normal synapse numbers in Tbr1^layer5 mutant mice. Immunofluorescence (IF) was used to detect excitatory (A, C) and inhibitory (B, D) synapses onto dendrites from mPFCx of Tbr1^wildtype (Rbp4-cre::tdTomato^f/+; green), Tbr1^layer5 CKOs (Tbr1^f/f::Rbp4-cre::tdTomato^f/+; orange) (n = 10 dendrites). Synapses were measured (i) 24 h and (ii) 4 weeks after injection with saline or LiCl at P180. Excitatory synapses were analyzed by VGlut1⁺ boutons and PSD95⁺ clusters co-localizing onto the dendrites from layer 5 neurons of mPFCx of Tbr1^wildtype (green) and Tbr1^layer5CKO (orange) mice 24 h (at P181; A, A’) and 4 weeks (P208; C, C’) after saline and/or LiCl was administered. Mann-Whitney ****p < 0.0001, ns = not significant. Inhibitory synaptic density was measured by VGat⁺ boutons and Gephyrin⁺ clusters co-localizing onto dendrites of mPFCx of Tbr1^wildtype (green) and Tbr1^layer5CKO (orange) 24 h (at P181; B, B’) and 4 weeks (P208; D, D’) after saline and/or LiCl was administered. Mann-Whitney ****p < 0.0001, ns = not significant. The Fiji ImageJ software was used to process confocal images for quantification. Two-tailed T-test with Mann-Whitney’s correction was used for pairwise comparisons