Figure 6.

Uncoupled intrinsic and synaptic excitability in DCX⁺ ABGCs after stroke. A, Input resistance, a parameter of passive neuronal properties, was plotted against mEPSC amplitude, a parameter of synaptic excitability. Sham DCX⁺ and sham DCX⁻ neurons were grouped together, representing the continuum of physiologically developed neurons. Regression lines (full lines) and the 95% confidence interval of the mean (dashed lines) were fitted to the data. mEPSC amplitude increases with maturation, as R_input decreases in sham DCX⁺/DCX⁻ cells (R² = 0.719). This relationship is lost after MCAO (R² = 0.041), with immature cells receiving disproportionately large excitatory synaptic currents. Statistical analysis by GLM showed a significant difference in the evolution of the two parameters between the two groups (n = 12 sham DCX⁺/DCX⁻, n = 9 MCAO DCX⁺; F_(1,17) = 6.1, p = 0.024). B, Output gain, a parameter of intrinsic excitability, was plotted against mEPSC amplitude, a parameter of synaptic excitability, under the same conditions as in A. Sham DCX⁺/DCX⁻ neurons have a progressive increase in synaptic excitability, which is accompanied by a decrease in output gain (R² = 0.783), thus preserving a balance between intrinsic and synaptic excitability. MCAO DCX⁺ show a dysregulated development of intrinsic and synaptic excitability (R² = 0.115), with highly excitable, immature neurons receiving disproportionately strong excitatory inputs. Statistical analysis revealed here as well a significant difference in the evolution of the two parameters in sham and MCAO groups (n = 12 sham DCX⁺/DCX⁻, n = 9 MCAO DCX⁺; F_(1,15) = 19.6, p = 0.0005).