PMC5601955_01
Sketch of the three electrode configurations. (A) Untargeted monopolar configuration, (B) targeted bipolar configuration, (C) targeted monopolar configuration, (D) common circumferential electrode, and (E) reference electrode.
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F1
UMC (Figure 1A): a circumferential electrode made of conductive fabric (silver-plated knitted fabric) was dampened with a small amount of water to decrease skin-electrode impedance and tied around the most proximal third of the thigh. Differential measurements were recorded between each of the electrodes and the common circumferential electrode (CCE) (Figure 1D). TBC (Figure 1B): eight pairs of pre-gelled electrodes were placed over the following eight muscles at an inter-electrode distance of 4 cm: sartorius, tensor fasciae latae, vastus medialis, rectus femoris, vastus lateralis, gracilis, the long head of the biceps femoris, and semitendinosus. In a different session, an untargeted monopolar configuration (UMC) was used (Figure 1).
Photographs depicting the trained motions (A) knee extension and flexion, (B) femoral rotation outwards and inwards, (C) ankle plantar flexion and dorsiflexion, and (D) and tibial rotation outwards and inwards.
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F2
The participants were instructed to follow a graphical user interface showing the movements to be performed (Figure 2), along with a progress bar signaling the duration of each contraction.
PMC5601955_02
Representation of the phantom limb pain location in the lower-limb amputee subject treated with phantom motor execution.
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F3
The subject described his phantom leg as of the same length as his normal leg and located the phantom pain in the foot (Figure 3, location 5).
Example of targeted monopolar configuration used for the phantom motor execution treatment of the patient with lower-limb amputation.
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F4
Figure 4 shows an example of the TMC configuration used.
Box plots presenting the results of the comparison of the three electrode configurations in terms of real-time metrics relative [i.e., (A) completion percentage, (B) completion time, (C) selection time, (D) real-time accuracy] and (E) offline accuracy. The boxplots represent only the data relative to non-amputated subjects. The line in the center of the boxes indicates the location of the median, the upper edge indicates the third quartile, the bottom edge represents the first quartile, and the whiskers indicate the data range. Along with every boxplot, it is possible to the mean value for each subject. Red dots represent non-amputees, while the square and a star marker represent the data points for the transtibial and the transfemoral amputee subject, respectively. Statistical significance (p < 0.05) is marked by the *.
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F5
The subject described his phantom leg as of the same length as his normal leg and located the phantom pain in the foot (Figure 3, location 5).