Figure 1: GABAergic depolarization in immature neocortical neurons in vivo.
From: GABA depolarizes immature neurons and inhibits network activity in the neonatal neocortex in vivo
(a) Sample time course of membrane resistance (Rm, moving average over five trials) in response to GABA (100 mM, 5 s) puff-applied from an epidural pipette. Current responses to hyperpolarizing voltage steps (–10 mV) are shown as insets. Scale bars, 100 pA, 20 ms. (b) Quantification (n=9, cells one-way repeated-measures ANOVA, Huynh–Feldt-corrected: P<0.001; post hoc Bonferroni-corrected pairwise comparisons: control–GABA: P<0.001, GABA–washout: P<0.01, control–washout: P>0.95). (c) Cell-attached voltage-clamp recordings from a single neuron sequentially exposed to GABA (top; 100 mM, 5 s) and glutamate (Glu, bottom; 100 mM, 5 s). Scale bars, 20 pA, 500 ms (top) and 15 pA, 15 ms (bottom). (d) Number of action currents per trial in response to GABA and glutamate in tight-seal (n=5) and loose-seal (n=7) configurations. (e) Cell-attached current-clamp recordings obtained from two different neurons show that puff-applied GABA (100 mM, 5 s) evoked depolarization (cell #2) and hyperpolarization (cell #4), respectively. Scale bars, 5 mV, 5 s. (c,e) Electromagnetic artefacts due to valve opening/closure were clipped for clarity. (f) Quantification. Each cell was tested in one to three trials. Each symbol represents a single trial. Depolarizing responses are indicated by red symbols, hyperpolarizing responses by blue symbols. Grey-shaded symbols refer to trials with amplitudes lower than three times the s.d. of the baseline noise. Arrows point to trials shown in e. CP, cortical plate (n=12 cells); MZ, marginal zone (n=3 cells). (b,d) Data presented as mean±s.e.m. **P<0.01, ***P<0.001.
