Fig. 6

Voltage-gated Ca²⁺ channels 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 5 mM Ni²⁺ (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 13 times threshold (right) in the presence of 5 mM Ni²⁺. The depolarizations produced by these two largely suprathreshold stimuli in the presence of Ni²⁺ (peak values -8 and 13 mV, respectively) are similar or larger than the CSD depolarization (peak value -7 mV), but the durations of the depolarizations are much shorter (7 and 15 s, respectively vs 112 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 5.0 ± 0.3 and 14.8 ± 0.8 times the CSD threshold duration, n= 5, N = 5) in the presence of Ni²⁺ (5 mM)