Figure 6. Granule cells coordinate neuronal activities on a fast timescale.

(a) Spectral density estimate for odor period normalized by that for baseline period (“evoked power”) averaged over all recordings (n = 10 recordings from 10 animals). Black = odor only, green = odor + LED. Mean and one standard deviation shown. Example spectrograms with odor only (top) and with additional GCL silencing (yellow bar; bottom). Hotter colors indicate greater power. Spectrograms are the average from 17 trials each. (c) Summary of evoked power averaged over gamma frequencies (40-100 Hz). Mean ± s.e.m. shown. (d-f) Gamma range activities on a single cell level. (d) Example of excitatory response evoked in an example TC (top). Gray bar indicates time of odor presentation. Scale bars = 20 mV, 0.4 s. (middle) Spike raster where timings of evoked APs are shown relative to a selected evoked spike (spike_ref) for 40 randomly chosen spike_ref. Spike autocorrelogram for this example cell is shown at the bottom (see methods). (e) as in (d) but with additional GCL silencing (yellow bar, top). Scale bars = 20 mV, 0.4 s. (f) Power spectra were obtained from the spike autocorrelogram for all TCs that showed excitatory responses (n = 9 cells from 8 animals) and averaged. Mean ± s.e.m are shown for odor only (black/gray) and with LED (green/pale green) conditions. Odors used = isoamylacetate, salicylaldehyde, eugenol, methylsalicylate and cinnamaldehyde at 2-5 % saturated vapor.