Coherence spectra are most consistent between sessions when estimated using rectified EMG signals.

<p>The most left graphs (A,E,I) depict the coherence spectra within the 15–35 Hz frequency range for the three different sessions for a subject #2. The other graphs show the presence and magnitude of the coherence for all subjects. Here the coherence magnitude is indicated in a gray scale, where a darker rectangle indicates a higher coherence. Each grayscale graph is a different combination of session and processing settings. For easy comparison with the other processing settings, HP10-R is depicted in the middle row. The confidence limit was subtracted from all coherence values.</p

Coherence variables show considerable within-subject variability for HP10-R and even larger for different processing settings.

<p>Effect of processing settings on within and between subject variation in the area of coherence (A,C) and peak coherence (B,D) for slow (A,B) and normal (C,D) walking speeds. Each marker indicates the variable value of a single session. The different marker styles and colors depict different processing steps.</p

Area of coherence increases with number of segments used to calculate the cohernce spectrum.

<p>Influence of number of segments on the area of coherence (A) and peak coherence (B) for HP10-R. Data of subject #1 for the slow walking condition were used. Each marker indicates the value calculated from a subset containing the specified number of segments. These subsets were randomly taken from a total of 421 (additional session 1, AS1) or 418 (additional session 2, AS2) segments. The solid line indicates the mean value as a function of the number of segments for AS1. The dashed line shows the mean for AS2. The separate values for AS2 are not shown.</p

Rectifying and filtering of EMG signals has a large effect on power and coherence spectra.

<p>Representative data for a single subject (Subject #2) showing the effect of rectifying and filtering on the EMG activity (A,D), cumulant density function (B,E), power spectrum (C, F) and coherence spectrum(G).</p

The across subject average correlations (µ ± std) between coherence spectra from different sessions.

<p>The across subject average correlations (µ ± std) between coherence spectra from different sessions.</p

Coherence variables show within-session variation, which is about equal to observed between-session variation.

<p>Variation of area of coherence (A) and peak coherence (B) within a single 10-min walking trail at 2.5 km/h for subject #1 for the HP10-R processing. The values were calculated for consecutive subsets of 100 segments. The 10-min walking trail was performed in two additional sessions (AS) each indicated with a different line/marker style.</p

Mean onset latencies of prime movers of postural responses (SE) to backward (tibialis anterior muscle) and forward (gastrocnemius medialis muscle) perturbations.

<p>*significant difference between trials with and without a SAS (main effect). +significant difference between anodal-tDCS and sham-tDCS (main effect).</p

EMG signals of a representative subject from the tibialis anterior muscle during ankle dorsiflexion with the dominant leg.

<p>Grey lines represent trials after sham-tDCS, black lines after anodal-tDCS. Dotted lines represent trials with a SAS, solid lines trials without a SAS.</p

Mean onset latencies (SE) during the simple reaction time tasks involving voluntary ankle dorsiflexion and wrist flexion.

<p>*significant difference between trials with and without a SAS (main effect). +significant difference between anodal-tDCS and sham-tDCS (main effect).</p