Fig. 6.

Field potential spikes are often found on ascending and descending slopes of GABAergic currents and only rarely on the current peaks. A, A barrage of GABAergic currents is seen in pyramidal neurons during the population events. The intracellular recording (bottom trace) is simultaneous with the field potential recording (top trace). The neuron was recorded at a distance of 100 μm from the extracellular electrode and whole-cell voltage-clamped to ∼0 mV. B, Correlation of the field potential spikes and GABAergic currents.Top panel, Distribution of field potential spikes around the spike occurring at t = 0. The values are pooled from six experiments and 805 spikes in 156 spontaneous events.Bottom panel, Mean GABAergic current around a field potential spike occurring at t = 0, dotted lines indicate the SEM (see Materials and Methods for details). As the GABAergic currents are positive (outward), negative mean values indicate that field potential spikes are inversely correlated with the GABAergic currents.