Does Motor Imagery Task Alter H-Reflex in FCR Muscle of The Human Hand?

Movement is one of the most important abilities of the human being. Neurological disorders, such as spinal cord injury, stroke and Parkinson's disease can change all aspects of a patient's life, from self-care to social behavior. One of the theories, which has a very strong evidence in rehabilitation, works on recovery of reflexes in order to treat patients. On the other hand, there has been a great deal of evidence that cerebrum has a very important role in recovery of functions. However, one open question is how these two views work together. In this research, change in the Hoffmann reflex (H-reflex) due to cortical activities was studied. The amplitude and delay of H-reflex before and after the motor imagery task were compared. Twelve healthy subjects participated in this study. Subjects were requested to imagine flexion and extension of wrist, and H-reflex was recorded during the imagery task. The EMG was recorded from flexor carpi radialis (FCR) muscle. There was a statistically significant difference between the H-reflex amplitude in the wrist flexion imagery and no-imagery condition (p-value = 0.002). However, there was no significant difference in the wrist extension imagery and no-imagery condition (p-value = 0.622). Thus, results can guide researchers to the conclusion that the motor imagery task may affect spinal reflexes.