Figure 2

Oddball and heel-strike locked voltage amplitude responses for a single subject (1) plotted over epochs from 0.5 s before to 1 s after the time-locking event. The color mapped oddball, time-locked, voltage responses of all (a, d), clean/good (b, e), and bad (c, f) channels during standing (top row) and walking (bottom row) are shown. Clean channels are defined as those free of movement and EEG artifact, and bad channels are those omitted per the criteria discussed in methods. The standing cases show the cognitive dynamics that can be resolved time-locked to the oddball. The walking cases demonstrate that these dynamics are lost due to walking artifact. Panel (g) shows the voltage amplitude response locked to left heel-strike and how significant the walking artifact is. Each channel voltage color is normalized to its average voltage. Channels are sorted and numbered by their correlation to the mean voltage signal with higher correlated signals at the bottom. The black box around 300 ms in (b) shows a example component of the p300 negative deflection across clean channels. This deflection is not visible during walking (panel e).