Figure 5.

Gamma-Coherent Synaptic Inhibition in Hippocampal GCs In Vivo

(A) Simultaneous recording of IPSCs and LFP. IPSCs were recorded in the WC voltage-clamp configuration at 0 mV, close to the reversal potential of AMPAR-mediated currents. Green, LFP recording; red, same LFP trace filtered in the theta (second trace from top) and gamma (third trace from top) frequency range; black, WC recording.

(B) Average coherence between IPSCs and LFP. Note the presence of a peak in the gamma frequency range and two additional peaks in theta and supragamma frequency range (arrows).

(C) Simultaneous recording of EPSCs and LFP. EPSCs were recorded in the WC voltage-clamp configuration at –70 mV, close to the GABA_AR reversal potential. Color code is the same as in (A).

(D) Average coherence between EPSCs and LFP. Note the presence of a peak at theta frequency (arrow). To evaluate the statistical significance of coherence in (B) and (D), we compared the original data (blue) to shuffled data (brown). Shaded areas indicate SEM. Control data were significantly different from shuffled data (p < 0.05). Data in (A) and (C) were recorded from the same individual cell; data in (B) and (D) were obtained from the same population of neurons (five cells with at least one cycle of sequential EPSC-IPSC-EPSC measurements).

(E) Maximal coherence (top) and corresponding frequency (bottom) for EPSCs and IPSCs.

(F) Total charge of EPSCs and IPSCs per theta cycle. Note that the ratio of inhibitory to excitatory charge was approximately constant, indicating that excitation and inhibition were balanced. Bars indicate mean ± SEM, circles represent data from individual experiments. Data points from the same experiment are connected by lines. EPSC data shown in (D) and (E) were also included in Figure 4E. All experiments were performed in awake rats (five cells). See also Figures S4 and S6.