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Updated: Mar 26, 2026
Functional Transcranial Doppler Ultrasound for Monitoring Cerebral Blood Flow
Published on: March 15, 2021
An online three-class Transcranial Doppler ultrasound brain computer interface
Anuja Goyal1, Ali-Akbar Samadani1, Anne-Marie Guerguerian2
1Bloorview Research Institute, Holland Bloorview Kids Rehabilitation Hospital, 150 Kilgour Road, Toronto, Ontario M4G 1R8, Canada; Institute of Biomaterials and Biomedical Engineering, University of Toronto, 164 College Street, Toronto, Ontario M5S 3G9, Canada.
This study introduces a novel brain-computer interface (BCI) using transcranial Doppler ultrasound (TCD). The vision-independent TCD BCI enables communication for individuals with motor disabilities, achieving higher information transfer rates than previous systems.
Area of Science:
- Neuroscience
- Biomedical Engineering
- Rehabilitation Technology
Background:
- Brain-computer interfaces (BCI) offer communication solutions for individuals with severe motor impairments.
- Transcranial Doppler (TCD) ultrasound measures cerebral blood flow velocities, enabling BCI development.
- Previous TCD BCIs relied on visual cues, which can be distracting for users.
Purpose of the Study:
- To investigate vision-independent, right-lateralized tasks for a TCD BCI system.
- To enhance user attention and improve BCI performance by removing visual task dependencies.
- To evaluate the efficacy of verbal fluency and motor imagery/3D-shape tracing tasks in a TCD BCI.
Main Methods:
- A bilateral TCD BCI was used with ten participants.
- Participants controlled an on-screen keyboard using verbal fluency, fist motor imagery, 3D-shape tracing, or rest.
- A linear discriminant classifier distinguished between the three distinct tasks.
Main Results:
- 3D-shape tracing proved more distinct than fist motor imagery.
- The system achieved a mean agreement of κ=0.43±0.17 for distinguishing between verbal fluency, 3D-shape tracing, and rest.
- The online communication system reached a mean information transfer rate (ITR) of 1.08±0.69 bits/min, with peaks up to 2.46 bits/min.
Conclusions:
- A three-class online TCD BCI is feasible without requiring visual task cues.
- The developed TCD BCI system demonstrates improved performance and information transfer rates compared to prior online systems.
- This approach holds significant potential for enhancing communication accessibility for individuals with motor disabilities.
