Relation between Cortical Activation and Effort during Robot-Mediated Walking in Healthy People: A Functional Near-Infrared Spectroscopy Neuroimaging Study (fNIRS)

Figure 1. Atalante® exoskeleton (Wandercraft company, Paris, France). (a) Participant using the exoskeleton Atalante®; (b) mechanical design with ranges of motion.

Figure 2. Position of the optodes. Schematics of the optode locations among the EEG 10/20 system. (a) A total of 18 optodes, including 10 light source (in yellow) and 8 detectors (in blue), were arranged on the scalp to enable 20-channel measurement. There were two additional short channels (CH21 and CH22). (b) The anatomical locations of the optodes were superimposed onto the normalized brain surface in the MNI standard brain template.

Figure 3. Results of the hemodynamic response by level of assistance (A100%, A50%, A0%, A−25%) for each channel. The results are expressed by mean (average of the participants). Graph locations were organized according to the anatomical correspondence using the EEG 10/20 system. The time window analyzed was 45 s, from 10 s before the beginning of the task to 35 s after the task. The red traces indicate HbO2 levels and the blue traces indicate HbR levels. The red boxes indicate a significant difference between rest and task periods for HbO2 levels. The blue boxes indicate a significant difference between rest and task periods for HbR levels. * p < 0.05; ** p < 0.01 (Benjamini–Hochberg correction).

Figure 4. Mean activation maps of cerebral cortex for HbO2 and HbR during gait for each level of assistance (A100%, A50%, A0%, A−25%). The data are t values, t: statistical value of sample t-test with a significance level of p < 0.05 (Benjamini–Hochberg correction). The change from red to yellow indicates that the degree of activation is from low to high. The coordinates in the figure show the activation range of the cerebral cortex in each level of assistance. Only statistically significant responses were illustrated. The data and maps were calculated and generated by NIRS-SPM.

Figure 5. Two-by-two comparisons of HbO2 levels for each level of assistance (A100%, A50%, A0%, A−25%). The data are t values, t: statistical value of sample t-test with a significance level of p < 0.05 (Benjamini–Hochberg correction). The change from red to yellow indicates that the degree of difference is from low to high. Only statistically significant comparisons were illustrated. The data and maps were calculated and generated by NIRS-SPM.