Functional near-infrared spectroscopy to probe sensorimotor region activation during electrical stimulation-evoked movement
This study used non-invasive functional near-infrared spectroscopy (fNIRS) neuroimaging to monitor bilateral sensorimotor region activation during unilateral voluntary (VOL) and neuromuscular electrical stimulation (NMES)-evoked movements. Methods. In eight healthy male volunteers, fNIRS was used to measure relative changes in oxyhaemoglobin (O2Hb) and deoxyhaemoglobin (HHb) concentrations from a cortical sensorimotor region of interest in the left (LH) and right (RH) hemispheres during NMES-evoked and VOL wrist extension movements of the right arm. Results. NMES-evoked movements induced significantly greater activation (increase in O2Hb and concomitant decrease in HHb) in the contralateral LH than in the ipsilateral RH (O2Hb: 0·44 ± 0·16 μM and 0·25 ± 0·22 μM, P = 0·017; HHb: −0·19 ± 0·10 μM and −0·12 ± 0·09 μM, P = 0·036, respectively) as did VOL movements (0·51 ± 0·24 μM and 0·34 ± 0·21 μM, P = 0·031; HHb: −0·18 ± 0·07 μM and −0·12 ± 0·04 μM, P = 0·05, respectively). There was no significant difference between conditions for O2Hb (P = 0·144) and HHb (P = 0·958). Conclusion. fNIRS neuroimaging enables quantification of bilateral sensorimotor regional activation profiles during voluntary and NMES-evoked wrist extension movements.