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 (O2 Hb) 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 O2 Hb and concomitant decrease in HHb) in the contralateral LH than in the ipsilateral RH (O2 Hb: 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 μΜ and 0·34 ± 0·21 μM, P = 0·031; HHb: -0·18 ± 0·07 μΜ and -0·12 ± 0·04 μΜ, P = 0·05, respectively). There was no significant difference between conditions for O2 Hb (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.