Collective oscillations in the CA3 region of the guinea pig hippocampal slice

A detailed model of the in vitro guinea pig hippocampal CA3 region has been constructed, using three neuronal types (pyramidal cells and two kinds of inhibitory cell). The model cells (up to 9900 of them) have dendrites and voltage-dependent and calcium-dependent conductances. The connectivity and unitary synaptic actions are defined experimentally by dual intracellular recordings. The model generates two basic types of oscillation: with inhibition blocked, synchronized epileptiform bursts occur at low rates; with inhibition present, low-amplitude population oscillations occur in which individual cells do not fire periodically. Both sorts of activity are observed in experiments.