Figure 5—figure supplement 7. | On cross-frequency phase-phase coupling between theta and gamma oscillations in the hippocampus

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

Figure 5—figure supplement 7.

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Federal University of Rio Grande do Norte, Brazil
Figure 5—figure supplement 7.
Download figureOpen in new tabFigure 5—figure supplement 7. The bump in the Rn:m curve of hippocampal LFPs highly depends on analyzing contiguous phase time series data.

Average Rn:m curves computed for theta- and gamma-filtered hippocampal LFPs. The green curves were obtained using 1 s (top) or 10 s (bottom) continuous epochs of the phase time series, sampled at 1000 Hz (same analysis as in Figure 5A). The blue curves were obtained by analyzing 1000 data points subsampled from the phase time series at 20 Hz (i.e., 50 ms sampling period, longer than a gamma cycle). The red curves were obtained by analyzing 1000 (top) or 10000 (bottom) data points randomly sampled from the phase time series. These plots show that the prominent bump in the Rn:m curve of actual LFPs only occurs for continuously sampled data (1000 Hz sampling rate), and therefore probably reflects the ‘sinusoidality’ imposed by the filter (see also Figure 2—figure supplement 1). But notice that a small Rn:m bump remains for θ−γS (see Figure 10—figure supplement 2). Due to limitation of total epoch length, we could not perform the 20 Hz subsampling analysis for 10000 points, but notice that the blue and red curves coincide for 1000 points.

DOI: http://dx.doi.org/10.7554/eLife.20515.020