Figure 3. Enhanced Inhibitory Gating in Mecp2 KO Mouse Visual Cortex.

(A) PV-immunofluorescence is elevated at P15 in Mecp2 KO animals (3 mice each, p < 0.01, Mann-Whitney test), and this difference persists into adulthood (see also Figure 2). The density of perisomatic PV-boutons upon pyramidal cell somata is significantly increased in the absence of Mecp2 starting already at P15 and throughout life (upper right, 3–4 mice each, versus WT; *p < 0.01, **p < 0.001, Mann-Whitney test). WT mice also exhibit a significant increase in PV-puncta across development (3–4 mice each, p < 0.01, Mann-Whitney test).The level of GAD65 within PV puncta is significantly decreased starting from P30 in Mecp2 KO mice compared to WT (lower right, 3–4 mice each, versus WT; *p < 0.01, **p < 0.001, Mann-Whitney test). Scale bar, 5 μm.

(B) Propagation of neuronal activity through layer 4 at threshold stimulation is reduced in upper layers in the Mecp2 KO mouse. Schematic of recording area indicating position of the stimulating electrode (black arrowhead) in the white matter (WM) and ROIs (squares) for analysis in upper and lower layers “on beam.” Pseudocolor peak response frame from VSDI movies of WT slices 15 ms after half maximal WM stimulus, revealing strong WT response propagation to the upper layers. The upper layer response in KO slices is suppressed at threshold stimulus intensity (graph arrow). Scale bar, 250 μm. Upper/lower layer response ratio as a function of WM stimulus intensity. All results expressed as mean ± SEM (4–5 mice each); *p < 0.001, t test.

See also Figure S2.