Figure 2.

Intracellular activity of hippocampal neurons from the KA-injected mouse in vivo. A, Voltage responses (top traces) of a neuron located in the CA1 region of the epileptic hippocampus to hyperpolarizing (average of 5 successive trials) and depolarizing (single-response) current pulses (bottom traces). B, Intracellular correlate (bottom traces) of LFP (top traces) interictal-like activities. B₁, Subthreshold events. In between the interictal spikes, the hippocampal (Hipp.) neuron displayed bursts of dPSPs (arrow), which were amplified (crossed arrow) when coincident with paroxysmal LFP. B₂, Suprathreshold events. Brief clusters of LFP spikes could be correlated with neuronal bursting, which were generated by large-amplitude depolarization gradually constructed by temporal summation of excitatory synaptic events (inset; calibration: 30 mV, 20 ms). C, D, Intracellular activity (bottom trace) of pyramidal neurons associated with LFP seizure activity (top trace). Note the abrupt depolarization at the onset of seizure (arrows) and the sustained neuronal depolarization throughout the local paroxysm. The inset in C, is the enlargement of the initial neuronal paroxysmal shift indicated by the arrow. Arrowheads indicate the mean interictal membrane potential. Records shown in A–C and D are from two separate experiments.