HEARING THOUGHTS:
University of Toronto graduate student Sarah Power
models ultrasound
headgear that could see the difference between two brain tasks.
Ultrasound transducers could make
a better brain-computer interface
(September 21, 2011) Ultrasound is good for more than monitoring
fetuses and identifying heart defects. According to engineers in Canada, it can
help tell what people are thinking as well. Their research suggests that
ultrasound-based devices could lead to a new kind of brain-computer interface.
Brain-computer interface
technology allows users to control devices with brain activity alone.
Researchers have focused primarily on clinical applications for people with
severe disabilities who would otherwise have difficulty interacting with the
outside world.
In addition to brain-computer interfaces
that involve electronics inserted directly into a patient’s head, researchers
are also developing a number of noninvasive methods. For instance,
electroencephalography (EEG) relies on electrodes attached to a person’s head;
functional magnetic resonance imaging (fMRI) uses powerful magnetic fields to
measure blood flow in the brain that telegraphs brain activity;
magnetoencephalography (MEG) detects the magnetic fields generated by clusters
of thousands of neurons; and near-infrared spectroscopy (NIRS) uses light to
scan for changes in blood hemoglobin concentrations.
Yet practical use of these
methods has so far been limited due to a number of drawbacks. For instance, EEG
faces "noise" from electrical signals sent by the muscles and eyes;
fMRI and MEG are very expensive and require large equipment; and NIRS, while
still early in development as a brain-computer interface technology, has a low
data-transmission rate.
Now biomedical engineer Tom Chau
and his colleagues at the University of Toronto reveal that ultrasound can also
monitor brain activity, suggesting that it could be used for brain-computer
interfaces.