title: Virtual Reality-Guided Motor Imagery Increases Corticomotor Excitability in Healthy Volunteers and Stroke Patients.
abstract: OBJECTIVE
  To investigate the effects of using motor imagery (MI) in combination with a virtual reality (VR) program on healthy volunteers and stroke patients. In addition, this study investigated whether task variability within the VR-guided MI programs would influence corticomotor excitability.
  
  
  METHODS
  The present study included 15 stroke patients and 15 healthy right-handed volunteers who were presented with four different conditions in a random order: rest, MI alone, VR-guided MI, and VR-guided MI with task variability. The corticomotor excitability of each participant was assessed before, during, and after each condition by measuring changes in the various parameters of motor-evoked potentials (MEPs) of the extensor carpi radials (ECR). Changes in intracortical inhibition (ICI) and intracortical facilitation (ICF) were calculated after each condition as percentages of inhibition (%INH) and facilitation (%FAC) at rest.
  
  
  RESULTS
  In both groups, the increases in MEP amplitudes were greater during the two VR-guided MI conditions than during MI alone. Additionally, the reductions in ECR %INH in both groups were greater under the condition involving VR-guided MI with task variability than under that involving VR-guided MI with regular interval.
  
  
  CONCLUSIONS
  The corticomotor excitability elicited by MI using a VR avatar representation was greater than that elicited by MI with real body observations. Furthermore, the use of task variability in a VR program may enhance neural regeneration after stroke by reducing ICI. The present findings support the use of various VR programs as well as the concept of combining MI with VR programs for neurorehabilitation.
authors.affiliation: Department of Rehabilitation Medicine, Eulji Hospital, Eulji University School of Medicine, Seoul, Korea.
authors.forename: Hyungjun
authors.identifier: 0000-0002-2360-7775
authors.initials: H
authors.lastname: Im
authors.affiliation: Department of Biomedical Engineering, Keimyung University, Daegu, Korea.
authors.forename: Jeunghun
authors.identifier: 0000-0002-9610-0078
authors.initials: J
authors.lastname: Ku
authors.affiliation: Department of Rehabilitation Medicine, Eulji Hospital, Eulji University School of Medicine, Seoul, Korea.
authors.forename: Hyun Jung
authors.identifier: 0000-0002-2198-5668
authors.initials: HJ
authors.lastname: Kim
authors.affiliation: Department of Rehabilitation Medicine, Eulji Hospital, Eulji University School of Medicine, Seoul, Korea.
authors.forename: Youn Joo
authors.identifier: 0000-0002-9938-5435
authors.initials: YJ
authors.lastname: Kang
keywords: Imagery (psychotherapy); Stroke; Transcranial magnetic stimulation; Upper extremity; Virtual reality exposure therapy