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. 2014 May 21;82(4):872–886. doi: 10.1016/j.neuron.2014.04.007

Figure 5.

Figure 5

Activity of Bistratified and O-LM Cells during SWRs

(A) Bistratified cells increased their firing rate strongly around and during SWRs (red asterisks). Top: LFP measured by an extracellular glass electrode in stratum pyramidale; middle: LFP band-pass filtered (130–230 Hz); bottom: action potentials of the recorded and labeled bistratified cell.

(B) O-LM cells were silent during the majority (left), but not all (right), SWRs (blue asterisks, both periods during sleep).

(C) Comparison of mean spike count per SWR of bistratified and O-LM cells recorded during sleep and wakefulness. The difference in spike counts between cell types depended on the behavioral state during which the SWRs occurred (p = 0.0396 for the interaction; repeated-measures ANOVA).

(D and E) Raster plots and average firing probability densities (top) of bistratified (D) and O-LM (E) cells relative to SWRs (w, wakefulness; s, sleep). Bistratified, but not O-LM cells, fired with higher probability during SWRs (colored bars in histogram) compared to the ±0.5 s (gray) surrounding the peak of SWR events. Overall, the firing probability of O-LM cells did not change during SWRs (blue bars in histogram); they decreased or rarely increased their firing probability. Raster plots were aligned to the peak SWR-power. Colored lines delineate the beginnings and ends of SWRs.

(F and G) Examples of SWR-related firing rates of bistratified (F) and O-LM (G) cells, during sleep and wakefulness. The distributions of measured firing rates per individual SWRs are displayed as cumulative distribution functions (CDFs). The distribution of bistratified cell firing rates (red) was significantly different from the median (black) of the surrogate sets (p < 0.05; two-sample KS test), and the right shift demonstrates an increase over the full range of firing rates. Surrogate sets of 1,000 firing rate-distributions are shown (gray; median, solid black line; 95% confidence intervals, broken lines). Insets: comparison of mean SWR-related firing rate (colored lines) with the distribution of surrogate mean SWR-related rates (black lines). The bistratified cell (red) was always strongly activated by SWRs (p < 0.05 for sleep; p < 0.05 for wakefulness, relative to the surrogate CDF). The measured distribution of the O-LM cell was also significantly different from the median (black) of the surrogate set (p < 0.05; two-sample KS test). The shift to the left or right of the measured CDF over part of the surrogate firing rate range indicates decreased or increased firing of the O-LM cell, respectively. Insets: during sleep, the mean firing rate of the O-LM cell (blue) was not different (p = 0.137, relative to the surrogate CDF) from the surrogate distribution (black). In contrast, during the awake condition, the measured mean firing rate of the O-LM cell was significantly increased during SWRs (p = 0.035, relative to the surrogate CDF). See also Figure S4.