Figure 7. SOM and PV Cells Preferentially Pace Narrow Low-Frequency Band and Wide High-Frequency Band Activities, Respectively.

(A) Top: a circuit diagram where ChR2-expressing SOM cells are rhythmically activated by 1-ms blue laser pulses (473 nm, 30 mW). Bottom: raster plot shows evoked spikes of a tagged SOM cell in the SOM::Ai27 mouse. Insets: box-and-whisker plots of the spike latencies and jitters of laser pulse-evoked first spikes in the SOM cells are shown (n = 23 recordings in 22 mice; p < 0.01, tested by stimulus-associated spike latency test [SALT]).

(B) Raw average local field potentials (LFPs) evoked by1-ms laser pulse to activate ChR2-expressing SOM cells, with increasing laser power from 0.3 to 30 mW, and the blockade of evoked LFPs (at 30 mW) by the epipial infusion of bicuculline (GABA_A receptor antagonist). Right: time constants of the rising and decay phases of evoked LFPs are shown (at 30 mW; n = 25 recordings in 7 mice).

(C) Top: trace of averaged resonant activity in LFPs under the 5-Hz stimulation of 1-ms blue laser pulses to ChR2-expressing SOM cells. Bottom: averaged power spectrum of LFPs during the baseline and the 5- and 40-Hz stimulation of laser pulses is shown.

(D) Average LFP’s power changes (power_light/power_baseline) induced by rhythmic activation of ChR2-expressing SOM cells with blue laser pulses at frequencies ranging from 1 to 200 Hz. Note that power values are normalized to the maximum power change in all tested frequency conditions (n = 9 recordings in 3 SOM::Ai27 and 3 SOM::Ai32 mice). Error bars, SEM.

(E–H) Similar to (A)–(D), respectively, except for the data of optogenetic activation of ChR2-expressing PV cells from the PV::Ai27 (or Ai32) mice (n = 30 PV cells in 21 mice in E; n = 12 recordings in 9 mice in F; n = 10 recordings in 7 PV::Ai27 and 2 PV::Ai32 mice in H). See also Figure S6.