case_images: PMC3819641_01
case_images: Motor-training. Four targets "center-out" task (A) with an example of a trajectory and some assisted-force-feedback vectors (orange arrows); physical representation (B) of the reaching task. The trajectory is shown for clarity, but during the motor task was never present.
case_images: fneur-04-00173-g001.jpg
case_images: PMC3819641_01_fneur-04-00173-g001.jpg
case_images: F1
case_images: E, S, and W) target positions was randomly selected in each trial for the ME (see Figure 1). Each target was represented by a white square of 18 mm. The patient was asked to move the cursor, controlling the end-effector from the center to the target in a pre-defined time window (0.5/0.7 s) and to perform the task as accurate as possible (see Figures 1 and 2).
case_images: Experimental procedure. Timing of self-paced trials with and without assisted-force-feedback (the force applied to the robotic arm was continuously updated every 16 ms). A self-paced trials starts by entering the center box, after 1.5 s a target appears (one out of four possible directions), thus the user plans the movement execution and initiates the movement toward the target; as soon as the target was reached (i.e., at the end of the trial) both visual and auditory feedback inform the user about the task completion; then the user comes back to the center position to start another trial. During BMI-training an assisted-force-feedback was provided according to the algorithm explained in Section "On-Line BMI Assisted-Force-Feedback."
case_images: fneur-04-00173-g002.jpg
case_images: PMC3819641_01_fneur-04-00173-g002.jpg
case_images: F2
case_images: The patient was asked to move the cursor, controlling the end-effector from the center to the target in a pre-defined time window (0.5/0.7 s) and to perform the task as accurate as possible (see Figures 1 and 2). Table 1). The MEM analysis window started 0.5 s before a movement interval onset, continued through this interval as a sliding window with steps of four samples to replicate the on-line settings (see Figure 2), and ended 0.5 s before a valid interval offset. This external program, referred as "robotic interface," is characterized by two concurrent processes: the first one controls the robotic arm and performs kinematic measurements (servo-loop rate equal to 1000 Hz); the second one handles the graphic interface adjusting the cursor position and scheduling each trial phase according to the timing of the task (see Figure 2).
case_images: Experimental protocol. Interval between blocks consisted of 2 days.
case_images: fneur-04-00173-g003.jpg
case_images: PMC3819641_01_fneur-04-00173-g003.jpg
case_images: F3
case_images: The robot training was performed on both healthy and paretic arms in daily sessions during 2 weeks, 3 days a week, resulting in 18 runs for each arm (see Figure 3). This configuration remained unchanged during on-line feedback BMI-training (see Figure 3).