A human brain, on an average, is made up of 100 billion neurons, which frequently communicate with each other. Such neuronal talking is generally monitored, studied and mapped through a routinely used magnetoencephalography (MEG). When neurons interact, their electrical activity produces a small magnetic field, which is recorded using highly sensitive magnetometers used in MEG.
The current setup of the MEG equipment consists of a fixed bulky apparatus weighing about 450kgs and requires the subject to sit very still under the scanner relative to the sensors. This makes it cumbersome to be used on children as well as patients with disorders who find it difficult to sit still.
To measure it with conventional MEG, scientists have people stick their heads inside a scanner like an “old-style hair dryer at a salon,” explains physicist Richard Bowtell of the University of Nottingham in the United Kingdom.
In an attempt to map brain activity while simulating a real-life situation, Bowtell has designed a portable MEG device called Optically Pumped Magnetometer (OPM), which can be worn like a mask to allow free movement of people during their scan. This is very convenient for all patient groups and definitely more useful since it involves studying brain activity while doing different tasks such as drinking, talking, walking etc. For instance, the researchers scanned volunteers while drinking tea or playing a ball game – neither of which is possible in a normal MEG scanner. Thus brain activity can be monitored in a more natural setting, doing their chores rather than just sitting idly under the scanner.
OPM was first tested on Elena Boto, a physicist at the University of Nottingham. She performed a series of tasks- including bending and pointing her finger, drinking from a cup, and bouncing a ball on a paddle using both devices. Interestingly, the brain activity recorded in both cases.
What is different about OPM?
The new portable sensor is equipped with miniature sensors to detect magnetic field replacing the traditional ones with heavy and bulky cooling system. These sensors detect the magnetic field in a different way and can be attached to the scalp using a 3D-printed helmet that can fit any sized head.
One limitation of this device is that the scanner works inside a specially designed room that can offset the influence Earth’s magnetic field. So the subject is not free to wander outside. Additionally, the cost of this device is extremely high. With the advancement of technology it is likely that the cost of these devices might come down.
Timothy Roberts, a neuroradiologist who works with children with autism at the Children’s Hospital of Philadelphia in Pennsylvania, says MEG masks like this one would be worth it.
Such a portable system opens the door for neuroscientists to study brain development in infants or study how brain activity of the patient varies in different neurological and movement disorders. It can also study natural interactions between subjects, each wearing a scanner while doing a group activity.
This article can be found at: https://www.nature.com/articles/nature26147