Blood flow velocity in middle cerebral artery during visuo-motor tasks using a mirror: a transcranial Doppler study

Mirror illusion means that standing in front of a mirror placed in sagittal plane, with the head tilted on one side and one arm stretched forward, one side of the body is reflected as if it were the other side by mirror visual feedback. The aim of this study was to monitor blood flow changes in middle cerebral artery (MCA) by use of transcranial Doppler (TCD) in individuals during motor tasks and tasks using mirror visual feedback. Eight young healthy volunteers (four male and four female) were included in the study. TCD recording in MCA was done during each task consisting of various motor and visuomotor activities using mirror illusion. Both MCA mean blow flow velocity (MBFV) was measured while the subjects were seated in a comfortable chair. The MCA MBFV recordings are presented as baseline values. During the illusion of motor hand activation, when the subject was making right hand flexions and watching its reflection in the mirror, with the left hand immobile, an increase was observed the contralateral MCA MBFV (task 3, +4.5% baseline value; P = 0.017). Furthermore, when the subject made left hand flexions while watching the reflection of the immobile right hand in the mirror, there was an increase in the right MCA MBFV (+5.6% baseline value; P = 0.044), which was more pronounced than during the illusion of motor hand activation (task 3) and less than during direct vision of hand flexion (task 2, +6.3% baseline value; P = 0.005). Our data showed that visual illusion of action, as well as direct action observation could increase the MCA MBFV, which brings forward the possible usage of mirror illusion as a tool in motor neurorehabilitation.