Comparison of brain areas for executed and imagined movements after motor training: An fNIRS study

In this paper, we investigate active brain regions for motor execution and motor imagination tasks after training with a rehabilitation robot. Functional near-infrared spectroscopy (fNIRS) is used to measure the hemodynamic responses in the motor cortices of five subjects. An assistive robot (IMT 2.0, connected to the right hand) is used during the training session to make the subject to reach a target point displayed on a computer screen. During the training, the subjects have to reach the target point in two directions (left and right) using right arm movement. Our intention is to investigate the differences between brain signals generated from left and right movements of the right hand. It was found that the same brain region was activated for both left- and right-directional motions. During the testing, we asked the subjects to imagine the executed movement. We found that although the imagined movement activity is weak but it appears in the same region as that of motor execution during the reach task. The results show that executed and imagined movements can be discriminated using fNIRS. However, for brain-computer interface it is difficult to generate two commands using only one arm movement signals.