Fig. 5.

Interneuronal networks produce gamma- and high-frequency oscillations in immature hippocampus. A, A spontaneous event in a P5 pyramidal neuron (the same as in Fig. 3) whole-cell voltage-clamped near the AMPA–kainate reversal potential (0 mV) demonstrating the GABAergic currents. B, A TF representation of the GABA currents in A. Note the series of brief high-frequency (here 100–200 Hz) components over the prominent oscillation in the gamma-frequency band. C, An averaged TF representation of 101 bursts of GABAergic currents showing a major peak in the 20–40 Hz range. Note the similarity between the frequency contents of GABA and AMPA–kainate (Fig. 3) currents in the lower gamma-band of the averaged TF representations. D, Frequency distribution of the GABA currents computed fromC to allow for a comparison with Figure 3. Gray line indicates 3 SDs of preburst noise.