Figure 1:
SWR LFP in a pyramidal population model. A. Top: Distribution of excitatory (blue) and inhibitory (red) synapses in apical dendrites and perisomatic regions, respectively, in two example pyramidal cells; one strongly-driven by numerous Schaffer-collateral excitatory synapses (blue dots) and one weakly-driven by fewer synapses (cyan dots). Traces depict average SWR IPSCs (mean ± SD, red) and EPSCs (blue and cyan), summed over all corresponding synapses. Inhibitory inputs are high-frequency (ripple) modulated. Stronger excitation leads to higher depolarization and larger IPSCs. Bottom: Somatic membrane potential of the two neurons during a series of SWR. B. Average wideband LFP during SWR (n = 165) in a population of 25 cells (green disks indicate somatic locations) consisting of negative deflections at the dendritic layer (sharp waves) and high-frequency perisomatic oscillations (ripples). Each trace represents the average LFP at the respective location. Layers, corresponding to stratum oriens (so), pyramidale (sp) and radiatum (sr), are in different colors. C. Average wideband (left) and 150–200 Hz filtered CSD (right) along the dashed axis in B. D. Wideband (black), 150–200 Hz filtered LFP segment (blue) and its amplitude (red) from the dotted location in B. Solid and dashed lines mark ripple-detection and ripple-edge thresholds, respectively. Detected ripple segments are highlighted in grey. Time segment is the same as in A. E. Aligned ripples (grey) and average wideband (top) and filtered ripple (bottom, black lines). F. Normalized power spectrum of the LFP from the dotted location in B. Ripples produce a peak at ~150–200 Hz. G. Spike histogram of all neurons, correlated with the average ripple, and spike phase distribution vector (right). Spikes are strongly correlated with ripple troughs (0o; p < 0.001 circular V-test).