Affiliations: Department of Biomedical Engineering, New Jersey
Institute of Technology, University Heights, Newark, NJ, USA | Department of Rehabilitation and Movement Sciences,
University of Medicine and Dentistry of New Jersey, Newark, NJ, USA | Department of Physical Therapy, New York University,
New York, NY, USA
Note: [] Corresponding author: Eugene Tunik, PhD, PT, Dept of
Rehabilitation and Movement Sciences, University of Medicine and Dentistry of
New Jersey, 65 Bergen St., Room 714, Newark, NJ 07103, USA. Tel.: +1 973 972
9535; E-mail: tunikeu@umdnj.edu
Abstract: Purpose: Emerging evidence shows that interactive virtual
environments (VEs) may be a promising tool for studying sensorimotor processes
and for rehabilitation. However, the potential of VEs to recruit action
observation-execution neural networks is largely unknown. For the first time, a
functional MRI-compatible virtual reality system (VR) has been developed to
provide a window into studying brain-behavior interactions. This system is
capable of measuring the complex span of hand-finger movements and
simultaneously streaming this kinematic data to control the motion of
representations of human hands in virtual reality. Methods: In a blocked fMRI design, thirteen healthy subjects
observed, with the intent to imitate (OTI), finger sequences performed by the
virtual hand avatar seen in 1st person perspective and animated by
pre-recorded kinematic data. Following this, subjects imitated the observed
sequence while viewing the virtual hand avatar animated by their own movement
in real-time. These blocks were interleaved with rest periods during which
subjects viewed static virtual hand avatars and control trials in which the
avatars were replaced with moving non-anthropomorphic objects. Results: We show three main findings. First, both observation
with intent to imitate and imitation with real-time virtual avatar feedback,
were associated with activation in a distributed frontoparietal network
typically recruited for observation and execution of real-world actions.
Second, we noted a time-variant increase in activation in the left insular
cortex for observation with intent to imitate actions performed by the virtual
avatar. Third, imitation with virtual avatar feedback (relative to the control
condition) was associated with a localized recruitment of the angular gyrus,
precuneus, and extrastriate body area, regions which are (along with insular
cortex) associated with the sense of agency. Conclusions: Our data suggest that the virtual hand avatars
may have served as disembodied training tools in the observation condition and
as embodied "extensions" of the subject's own body (pseudo-tools) in the
imitation. These data advance our understanding of the brain-behavior
interactions when performing actions in VE and have implications in the
development of observation- and imitation-based VR rehabilitation paradigms.
Keywords: Virtual environment, VR, motor control, imitation, hand
