# Figure 5—figure supplement 1. | On cross-frequency phase-phase coupling between theta and gamma oscillations in the hippocampus

# On cross-frequency phase-phase coupling between theta and gamma oscillations in the hippocampus

## Figure 5—figure supplement 1.

- Robson Scheffer-Teixeira
- Adriano BL Tort

Federal University of Rio Grande do Norte, Brazil

Download figureOpen in new tabFigure 5—figure supplement 1. Lack of evidence for cross-frequency phase-phase coupling between theta and gamma oscillations using alternative phase-locking metrics.(**A**) The left plots show the mean radial distance (R) computed for gamma phases in different theta phase bins, as described in Sauseng et al. (2009). The lines denote the mean ± SD over all channels across animals (n = 16 channels per rat x seven rats); 300 1 s long epochs were analyzed for each channel. Note that original and surrogate R values overlap. The variations of R values within a theta cycle are explained by the different number of theta phase bins (right bar plot), which leads to different number of analyzed samples; the higher the number of analyzed samples, the lower the R (see also Figure 2C). (**B**) The first column shows the mean pairwise phase consistency (PPC) between gamma and accelerated theta phases as a function of the number of $\mathrm{\Delta}{\phi}_{nm}$ samples (dashed lines denote SD over individual PPC estimates; n = 112 channels x 1000 PPC estimates per channel). Since PPC requires independent observations (Vinck et al., 2010), $\mathrm{\Delta}{\phi}_{nm}$ was randomly sampled to avoid the statistical dependence among neighboring data points imposed by the filter (Figure 2—figure supplement 1; see also Figure 5—figure supplement 7). The second column shows mean PPC as function of n:m ratio (individual PPC estimates were computed using 1000 $\mathrm{\Delta}{\phi}_{nm}$ samples); the boxplot distributions show PPC values at selected n:m ratios, as labeled. PPC values are very low for all analyzed frequency pairs and not statistically different from zero.

**DOI:** http://dx.doi.org/10.7554/eLife.20515.014