Dr. Josephine Flockton of the FETAL-MIND research team demonstrates how a pregnant participant would rest on the fetal MEG machine for acquisition of fetal data.
How does the human brain develop? And when does the mind begin?
Fetal MEG is a tool for answering these questions. MEG = magnetoencephalography. That’s a long fancy word, but it basically means technology that reads magnetic fields generated by the brain. The brain has electrical currents, and each of these currents generates a very weak magnetic field. These magnetic fields give us information above sensory processing and perceptual processes. That’s what MEG is used for. Fetal MEG is the same technology, but applied to fetuses after 25 weeks’ gestation, mostly in the third trimester.
This is a tough problem. The brain’s magnetic fields are weak. About a billion times weaker than the magnetic field that moves a compass needle. And in the fetal brain, it’s even weaker.
The solution? Right now, it’s SQUIDs. No, not the sea animal. SQUID are superconducting quantum sensors. They are kept extremely cold by liquid helium. In this liquid helium bath, they are able to detect unbelievably weak magnetic fields, like those of the fetal brain. But they also detect the magnetic fields of the mother’s heart, and the fetus’s heart. These other magnetic fields, while also weak in absolute terms, are much “louder” than the magnetic field from the fetal brain, making the fetal brain hard to “hear”. Listening to the quiet fetal brain amidst this noise is a true engineering challenge.
There’s more to this challenge. SQUIDs have to be kept in a special shaped container, or dewar. When an MEG system is built, the dewar is generally shaped for the adult head, like a helmet. But for fetal MEG, that’s the wrong shape. The SQUIDs need to be kept in a shield, one that matches the shape of a pregnant woman’s abdomen.
The fMEG Center research team, overlooking Tübingen.
Because of this last challenge, fetal MEG is rare. Only two sites in the world have SQUID machines for fetal MEG. Both of these machines are called SARA. This stands for SQUID Array for Reproductive Assessment. The first one has been operating in Little Rock, Arkansas, since the year 2000, through the University of Arkansas for Medical Sciences. The second one has been operating in Tübingen, Germany, since 2008, through the University Hospital Tübingen and the Helmholtz Center Munich.
A long exposure photograph of a fetal MEG session using visual stimuli.