Fig. 4

NMDARs are necessary for CSD initiation. A Upper panels: representative membrane potential changes recorded in a L2/3 pyramidal cell located near the site of application of KCl in response to a CSD threshold KCl stimulus in control (left) and in the presence of 20 µM MK-801 (right). Lower panels: membrane potential changes recorded in the same L2/3 pyramidal cell in response to largely suprathreshold KCl stimuli of duration 4 times threshold (left) and 11 times threshold (right) in the presence of 20 µM MK-801. The depolarizations produced by these two largely suprathreshold stimuli in the presence of MK-801 (peak values 1 and 10 mV, respectively) are similar or larger than the CSD depolarization (peak value 1 mV), but the durations of the depolarizations are much shorter (16 and 47 s, respectively vs 102 s for the CSD depolarization). The insets in the four panels show the corresponding IOS changes (recorded simultaneously to voltage) at different distances from the KCl puffer. B Average peak depolarization voltage (peak V, left panel) and duration of the depolarization at half amplitude (HW duration, right panel) elicited by CSD threshold KCl stimuli in control and by largely suprathreshold KCl stimuli (of average duration 3.8 ± 0.2 and 11.6 ± 0.7 times the CSD threshold duration, n = 8, N = 6) in the presence of MK-801 (20-50 µM).