Monitoring the motor cortex hemodynamic response function in freely moving walking subjects: a time-domain fNIRS pilot study

Fig. 1. (a) Sketch showing the experimental protocol used in the study. For each task (forward walking, backward walking, and stand still), five repetitions have been performed. (b) The probe was positioned following the electroencephalography (EEG) 10/20 map system and the position was C1 in the motor cortex area.

Fig. 2. Time course of hemodynamic parameters in the three tasks for subject #3: (a) finger tapping; (b) forward walking; and (c) backward walking. Data are for one subject and five repetitions. Round dots represent raw data of O2Hb (red) and HHb (blue) absolute concentration. Thicker lines show the fitted HRF for each repetition while gray shaded areas highlight the tasks’ periods.

Fig. 3. Time courses of O2Hb (red) and HHb (blue) for the three different subjects during the three different tasks. Plots report the mean (filled dots) and standard deviation (shaded area) over the five repetitions for each time point. Black asterisks are used to highlight significant activations with respect to the baseline (p<0.05). Solid lines represent the result of the adaptive HRF fit over the averaged repetitions.

Fig. 4. Mean over three subjects, performing five repetitions of three different tasks (see columns): standstill (control condition), forward walking, and backward walking. Round dots represent raw data of O2Hb (red) and HHb (blue) absolute concentration in time. Thicker lines show the fitted HRF for each repetition. Gray shaded areas highlight the task time periods, and shaded error bars represent the standard deviation resulting from the five repetitions average and three different subjects. Black asterisks are used to highlight significant activations (p<0.05).