Six measures descriptive of frequency distribution characteristics. Top row: (A) Frequency of the spectral peak, (B) Full-width half-max, and (C) Distribution skewness. Bottom row: (D) Amplitude of the spectral peak, (E) ALFF between 0.01 and 0.073 Hz, and (F) fractional ALFF between 0.01 and 0.073 Hz. Actually tested range was 0.009–0.0736 Hz due to discretization of the frequencies. Statistical significance: *p < 0.05. All six measures were derived from spectra smoothed with Gaussian filter (σ = 2). Open circles signify data-points that fell outside the whiskers. ALFF, amplitude of low-frequency fluctuation.