Designing a new brain scanner (MEG)


All brain cells communicate with each other
by passing tiny little electrical currents. Those electrical currents
generate magnetic fields and those fields exist
outside the head. So in MEG what we try to do,
is measure the magnetic fields that occur outside the head that are
generated by currents in your brain and by measuring those magnetic fields we can then infer what your brain
is doing at any one time. There are three main limitations of
the current generation of technology. One is that the signals
we measure are very low Two, you have to keep incredibly still
whilst you’re being scanned And three, it doesn’t really work for children. The quantum sensors that we’re working with, they’re very light and their external surface
is at room temperature. So unlike the traditional sensors,
which have to be cryocooled, these things can be mounted
directly onto the scalp surface so we can bring them into much
closer proximity to the brain. That increases the amount
of signal that we get; increased signal-to-noise,
and therefore greater sensitivity. They’re also very light, which means that we can put
them on the scalp surface and the subjects who are being scanned can move their head around
whilst they’re being scanned. So they don’t have to keep still anymore. That opens up lots of new avenues, in particular scanning patients who
find it harder to keep still or scanning children. Now, the other advantage for
scanning children, of course, is it’s no longer a one-size-fits-all helmet, instead we can build a
bespoke helmet to fit anyone. So we could have a two-year-old,
three-year-old, four-year-old and we can get the same sensitivity
as we would do for an adult. So we can get a full
three-dimensional picture of what the magnetic field looks like
outside somebody’s head. Once we’ve measured
that magnetic field, then we can use that to infer what
the currents were in the brain that were generating
those magnetic fields. So we can work out exactly what
the brain electrophysiology is that’s supporting ongoing cognition,
ongoing control in our subjects. The main UCL interest in this project is that
it gives us a new kind of brain scanner, that allows us to study things that
we’ve never been able to study before, and people who have never been able to be scanned
in a neuroimaging environment before – different patient groups,
like children for example. We’re right opposite the
National Hospital for Neurosurgery and we’re right next to
Great Ormond Street Hospital and the patient’s we hope to recruit from
these centers are suffering with epilepsy. And what we think these sensors will do, they’ll help the surgeons
better target where they operate and speed up the process, so they remove
the need for some unnecessary operations and result in earlier treatments
and earlier diagnosis.

4 thoughts on “Designing a new brain scanner (MEG)

  1. Fantastic. What's the signal to noise ratio? MEG isn't needed for surgery. EEG is sufficient and has a higher SNR.

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