Figure 6.

Spectral changes with velocity. A, The PSD across low to high velocities for frequency ranges up to 500 Hz. The power of θ and its associated harmonics increases with faster running velocities. This increase in θ and harmonic power is associated with a decrease in the power in the inter-θ/harmonic frequency bands at higher running speeds. B, The PSD across the 25- to 240-Hz frequency ranges. At higher velocities, power in the 25–50 range decreases. Compare to Ahmed and Mehta (2012; Fig. 2).