Fig. 1

Schematic diagram of the ankle tracking system and experimental setting during testing and learning. A The IMU sensor module used in testing and learning. B Examples of the 72-s-long repeated (six cycles of the same sequence) and random sequences generated by the interface software of the system and used in the baseline and retention tests. C An illustration of the target and ankle locations displaying on the screen to serve as real-time visual feedback to the participant. D A diagram of the experimental setting. The participant sat in front of a computer screen in a standard position, with the IMU sensor module worn on the non-dominant foot, and tracked the target cursor as accurately as possible with ankle dorsi- and plantar-flexion of the non-dominant foot. The x-axis of the IMU sensor was aligned to the mediolateral direction of the non-dominant foot, with the positive x, y, and z values on their corresponding axes pointing in the left, posterior, and superior directions, respectively. IMU: inertial measurement unit; MRI: Magnetic Resonance Imaging