Figure 4.

Peri-infarct Excitable Immature Neurons Acquire GABAergic Synaptic Input in the Stroke-Injured Cortex

(A–C) Properties of three unique classes of cortical GFP/DsRed+ cells post stroke. (A1–A3) Current traces resulting from voltage steps, with insets expanding on the 10 ms following depolarizing voltage steps. Significant inward currents were observed in both class 2 (A2) and class 3 (A3) cells. (B1–B3) I-V graphs of the amplitude 5 ms (black) and 180–190 ms (red) from voltage-step onset. (C1–C3) Voltage traces corresponding to current steps.

(D) Current traces of an evoked PSC, reversing at −40 mV.

(E) Traces (E1) and scatterplot (E2) of evoked PSC amplitude before and after application of bicuculline methiodide (Bic) (20 μM).

(F) Evoked PSCs in class 2 (red), class 3 (blue), and combined 2 and 3 (black) cells are blocked by Bic (p < 0.01, paired t test).

(G) Current traces of sPSCs (Vh, −70 mV), for class 1, 2 and 3. Lower panel, cell-averaged sPSC event from single voltage-clamp recordings (individual events in gray).

(H) Cell-averaged sPSC amplitude (H1) and frequency (H2) (n = 12 [class 1], 14 [class 2], 7 [class 3]).

(I) Proportion of peri-infarct GFP/DsRed+ cells showing one of three electrophysiological phenotypes, classified by voltage-step response.

(J) Traces (J1) and scatterplot (J2) of sPSCs before and after Bic application (20 μM).

(K) Cell-averaged sPSC frequency in class 2 (red), class 3 (blue), and combined 2 and 3 (black) cells showing that sPSCs frequency is blocked by Bic (p < 0.05, paired t test). Ctl., control; Amp., amplitude; Freq., frequency. Data: mean ± SEM.