Remapping in the ipsilesional motor cortex after VR-based training: a pilot fMRI study

Abstract

In a single case longitudinal study, a 70 year old female subject who has had a subcortical stroke 8 years prior, was tested three times in fMRI using an interactive MRI-compatible VR environment. The subject performed sequential finger movements with her right (unaffected) hand. Her hand motion (recorded with the data glove) animated either the ipsilateral (corresponding) or contralateral (mirrored) virtual hand model. In a visual feedback control condition, the virtual hand models were replaced with ellipsoids. In between the second and third session, the patient participated in an intensive, two-week long VR-based training of her affected upper extremity. When comparing activation in the mirrored versus the non-mirrored virtual visual feedback condition, no significant activation was noted in motor or premotor areas in the baseline 1 or baseline 2 sessions. However, increased activation in the ipsilesional motor cortex occurred as a result of training, despite the absence of active involvement of the ipsilesional motor cortex in this condition. The left motor cortex was also recruited in this condition (though weaker) despite the subtracted out ellipsoid condition (in which subjects also moved their hand). Thus, the contralateral (mirrored) visual feedback may have had a facilitory effect bilaterally. These findings might have some important implications for the development of novel therapies in the acute phase, when paresis and the potential for neural remapping are greatest.

Figures

Fig. 1

Top: The virtual environment used in the current paradigm. We extracted the essential component common to all of our virtual environments, the virtual hands, over a plane background. Bottom: picture of subject’s hands wearing 5DT data gloves that actuated motion of the virtual hand models.

Fig. 2

A chronic stroke patient performed a finger sequence with the less affected RIGHT hand. The panels show the activations that were significantly greater when viewing the corresponding finger motion of the LEFT virtual hand (i.e. activation related to ‘mirror’ viewing) than when viewing moving ellipsoids. The right panel shows that after two weeks of intensive training, viewing the LEFT virtual hand while moving the RIGHT hand led to significantly greater bilateral activation of the primary motor cortex, especially IPSILATERAL to the moving hand (i.e. contralateral to the observed virtual hand).