Article

Several neurorehabilitation strategies have been introduced over the
last decade based on the so-called simulation hypothesis. This hypothesis states
that a neural network located in primary and secondary motor areas is activated
not only during overt motor execution, but also during observation or imagery of
the same motor action. Based on this hypothesis, we investigated the combination
of a virtual reality (VR) based neurorehabilitation system together with a
wireless functional near infrared spectroscopy (fNIRS) instrument. This
combination is particularly appealing from a rehabilitation perspective as it may
allow minimally constrained monitoring during neurorehabilitative training.
METHODS: fNIRS was applied over F3 of healthy subjects during task performance in
a virtual reality (VR) environment: 1) 'unilateral' group (N = 15), contralateral
recording during observation, motor imagery, observation & motor imagery, and
imitation of a grasping task performed by a virtual limb (first-person
perspective view) using the right hand; 2) 'bilateral' group (N = 8), bilateral
recording during observation and imitation of the same task using the right and
left hand alternately. RESULTS: In the unilateral group, significant
within-condition oxy-hemoglobin concentration Delta[O2Hb] changes (mean +/- SD
mumol/l) were found for motor imagery (0.0868 +/- 0.5201 mumol/l) and imitation
(0.1715 +/- 0.4567 mumol/l). In addition, the bilateral group showed a
significant within-condition Delta[O2Hb] change for observation (0.0924 +/-
0.3369 mumol/l) as well as between-conditions with lower Delta[O2Hb] amplitudes
during observation compared to imitation, especially in the ipsilateral
hemisphere (p < 0.001). Further, in the bilateral group, imitation using the
non-dominant (left) hand resulted in larger Delta[O2Hb] changes in both the ipsi-
and contralateral hemispheres as compared to using the dominant (right) hand.
CONCLUSIONS: This study shows that our combined VR-fNIRS based
neurorehabilitation system can activate the action-observation system as
described by the simulation hypothesis during performance of observation, motor
imagery and imitation of hand actions elicited by a VR environment. Further, in
accordance with previous studies, the findings of this study revealed that both
inter-subject variability and handedness need to be taken into account when
recording in untrained subjects. These findings are of relevance for
demonstrating the potential of the VR-fNIRS instrument in neurofeedback
applications.

Langue : ANGLAIS