Extraction of low and high frequency components (LFC and HFC) from the ECoG recordings.

<p>Recordings in every channel were first re-referenced using the common average over all recording channels that do not show epileptic activity. To get the LFC, the re-referenced signal was low-pass filtered using a Savitzky-Golay filter (symmetric, 2^nd order, 250 ms window length). To get the HFC, the re-referenced signal is transformed to the time-frequency space using short-time Fourier transform. The amplitudes of the transformed signal were then divided by the average baseline amplitude for every frequency bin separately. The HFC was defined as the average normalized amplitudes across all bins within the HFC frequency range (see Methods for a definition of the frequency ranges).To correct for movement related neuronal activity, MRNRs were subtracted.