Fig. 4. NMDA-R-dependent seizure activity caused by Mg²⁺-free condition in pyramidal neurons in cortical slices.

A, Representative whole-cell current-clamp recording from a layer V pyramidal neuron. Current injection of −150 and +150 pA induced hyperpolarization and action potential firings, respectively, at resting membrane potential of −63 mV. B, Recording from another layer V pyramidal neuron. This neuron showed repetitive spontaneous depolarization with accompanying spike firings in Mg²⁺-free condition (Mg²⁺-free), which was abolished by bath-application of d-APV (50 μM), an NMDA-R antagonist for five min (APV), but resumed by washing d-APV out of the bathing medium (Wash of APV). C, Recording from a layer V pyramidal neuron in control condition containing 1.2mM Mg²⁺ (Normal ACSF). The neuron was silent in control condition. D, Recording from a layer II/III pyramidal neuron exhibiting rhythmic spontaneous depolarization with regular-spikings in Mg²⁺-free condition. E, Recording from a layer II/III pyramidal neuron, which was silent, in control condition.