Similar Sensorimotor Activations with and without Virtual Limbs During Action Execution and Observation in Neurorehabilitation Systems

Virtual reality rehabilitation systems often represent actions through virtual limbs. However, previous observation-only studies suggest that frontoparietal networks involved in action observation and execution may also be engaged by simpler virtual effectors. In the present fMRI study, we examined whether the visual presence of a virtual limb modulates brain activity during both action execution and action observation in a virtual neurorehabilitation task. Twenty-four healthy right-handed volunteers performed a cancellation task under four conditions: dot execution, hand execution, dot observation, and hand observation. Analyses showed similar frontoparietal and sensorimotor activations across hand and dot conditions in both runs, and direct hand-versus-dot comparisons did not reveal significant corrected differences. Under the visuomotor conditions tested here, the visual presence of a virtual limb was not associated with substantial differences in overall frontoparietal/sensorimotor activations. These findings support the development of more flexible virtual rehabilitation tasks and broaden the range of visual effectors that may be considered in future system design.