Stimulus-induced and spontaneous membrane potential changes in CA3 pyramidal cells. A, EPSP/IPSP sequence induced by a short stimulus train applied on the mossy fibers in normal (a) and in low-[Mg²⁺] (b) ACSF. Stimuli are indicated with a short bar below the traces, and the dotted line indicates the resting membrane potential of the cell. B, Interictal activity within a single CA3 neuron was represented by packets of synaptic inputs often resulting in a burst of action potentials. The discharge marked with an asterisk is seen to the right on a shorter time scale. C, SLEs consisted of an IBP, a TLP with high-frequency, small-amplitude oscillations (∼5 Hz) on a large depolarization shift, and a CLADP of variable length, while membrane potential slowly recovered to baseline or even hyperpolarized. D, The traces show the IBP of spontaneous (a) and a stimulus-induced (b) SLE (stimuli are indicated with a short bar below the traces). The traces on the right are from the TLP (c) and the CLADP (d) phases.