Sign In

A subscription to JoVE is required to view this content. Sign in or start your free trial.

In This Article

  • Summary
  • Abstract
  • Introduction
  • Protocol
  • Representative Results
  • Discussion
  • Acknowledgements
  • Materials
  • References
  • Reprints and Permissions

Summary

The goal was to design, build, and pilot a novel virtual reality task to detect and characterize unilateral spatial neglect, a syndrome affecting 23-46% of acute stroke survivors, expanding the role of virtual reality in the study and management of neurologic disease.

Abstract

Unilateral spatial neglect (USN) is a syndrome characterized by inattention to or inaction in one side of space and affects between 23-46% of acute stroke survivors. The diagnosis and characterization of these symptoms in individual patients can be challenging and often requires skilled clinical staff. Virtual reality (VR) presents an opportunity to develop novel assessment tools for patients with USN.

We aimed to design and build a VR tool to detect and characterize subtle USN symptoms, and to test the tool on subjects treated with inhibitory repetitive transcranial magnetic stimulation (TMS) of cortical regions associated with USN.

We created three experimental conditions by applying TMS to two distinct regions of cortex associated with visuospatial processing- the superior temporal gyrus (STG) and the supramarginal gyrus (SMG) - and applied sham TMS as a control. We then placed subjects in a virtual reality environment in which they were asked to identify the flowers with lateral asymmetries of flowers distributed across bushes in both hemispaces, with dynamic difficulty adjustment based on each subject's performance.

We found significant differences in average head yaw between subjects stimulated at the STG and those stimulated at the SMG and marginally significant effects in the average visual axis.

VR technology is becoming more accessible, affordable, and robust, presenting an exciting opportunity to create useful and novel game-like tools. In conjunction with TMS, these tools could be used to study specific, isolated, artificial neurological deficits in healthy subjects, informing the creation of VR-based diagnostic tools for patients with deficits due to acquired brain injury. This study is the first to our knowledge in which artificially generated USN symptoms have been evaluated with a VR task.

Introduction

Unilateral spatial neglect (USN) is a syndrome characterized by inattention to or inaction in one side of space that affects between 23-46% of acute stroke survivors, most commonly involving injury to the right cerebral hemisphere and resulting in a tendency to ignore the left side of space and/or the survivor's body1,2. Although the majority of patients with USN experience significant recovery in the short term, subtle USN symptoms often persist3. USN can increase patient risk for falls and impede activities of daily living2,4

Protocol

This study was approved by the local Institutional Review Board and meets all criteria set forth by Good Clinical Practice Guidelines. All participants provided informed consent before any study procedures began. Study participants were expected to participate in three separate sessions (outlined in Table 1). The elements of the experiment are described in stepwise fashion below. Session order was randomized.

Representative Results

Data were collected from healthy individuals using the protocol outlined above to demonstrate how the different variables that can be extracted from the virtual reality task can be analyzed to detect subtle differences between groups.

In this study, 7 individuals (2 male) with an average age of 25.6 and an average of 16.8 years of education each underwent three separate sessions of TMS. These subjects were broken into two groups.......

Discussion

We successfully induced and measured USN symptoms with TMS and VR, respectively. While we did not have significant results when compared to sham trials, we were able to compare multiple metrics of egocentric neglect (average head angle, time spent looking at flowers in either hemispace) and allocentric neglect (performance in selecting flowers with asymmetric petals on the left vs. the right side) between the different experimental groups, and found significant differences in average head angle between subjects stimulate.......

Acknowledgements

This work was supported by the University Research Fund (URF) from the University of Pennsylvania, and the American Heart Association's Student Scholarships in Cerebrovascular Disease & Stroke. Special thanks to the researchers, clinicians and staff of the Laboratory for Cognition and Neural Stimulation for their ongoing support.

....

Materials

NameCompanyCatalog NumberComments
AirFilm Coil (AFC) Rapid VersionMagstimN/AAir-cooled TMS coil
Alienware 17 R4 LaptopDellN/ANVIDIA GeForce GTX 1060 (full specs at https://topics-cdn.dell.com/pdf/alienware-17-laptop_users-guide_en-us.pdf)
BrainSight 2.0 TMS Neuronavigation SoftwareRogue Research IncN/ATMS neural targeting software
CED 1902 Isolated pre-amplifierCambridge Electronic Design LimtedN/AEMG pre-amplifier
CED Micro 401 mkIICambridge Electronic Design LimtedN/AMulti-channel waveform data acquisition unit
CED Signal 5Cambridge Electronic Design LimtedN/ASweep-based data acquisition and analysis software. Used to measure TMS evoked motor responses.
HTC Vive Binocular Add-onPupil LabsN/AHTC Vive, Vive Pro, or Vive Cosmos eye tracking add-on with 2 x 200Hz eye cameras.
Magstim D70 Remote CoilMagstimN/AHand-held TMS coil
Magstim Super Rapid 2 plus 1MagstimN/ATranscranial Magnetic Stimulation Unit
Unity 2018UnityN/Across-platform VR game engine
Vive ProHTC ViveN/AVR hardware system with external motion sensors; 1440x1600 pixels per eye, 90 Hz refresh rate, 110° FoV

References

  1. Heilman, K. M., Bowers, D., Coslett, H. B., Whelan, H., Watson, R. T. Directional Hypokinesia: Prolonged Reaction Times for Leftward Movements in Patients with Right Hemisphere Lesions and Neglect. Neurology. 35 (6), 855-859 (1985).
  2. Paolucci, S., Antonucci, G., Grasso, M. G., Pizzamiglio, L.

Explore More Articles

Virtual RealityUnilateral Spatial NeglectData CollectionAssessment ToolsLine BisectionBells TestStar CancellationOtas Circle CancellationTMSNeuronavigation3D Brain ModelingOptical Tracking

This article has been published

Video Coming Soon

JoVE Logo

Privacy

Terms of Use

Policies

Research

Education

ABOUT JoVE

Copyright © 2024 MyJoVE Corporation. All rights reserved