In the dystopian world of my novel, the government forces people to have annual scans in machines that read their memories. In the real world that isn’t possible yet, but it is possible to ‘read’ brain function by magnetoencephalography (MEG). MEG machines are like a giant helmet containing around 300 little tiles that directly measure magnetic fields coming from the brain. These tiles are called SQUIDS (superconducting quantum interference devices) and can pinpoint where brain activity is occurring down to the nearest millimetre.
MEG works because an electrical current is produced when neurons fire, and this in turn generates a magnetic field. Electroencephalography or EEG directly measures the brain’s electrical activity, but this is obscured by the skull so to get accurate measurements an electrode must be poked into the brain. MEG, on the other hand, is non invasive.
The magnetic fields created by the brain are tiny in comparison with that of the earth or of the man made electrical currents that surround us. So the MEG machines and the rooms they are in have shields to protect against the noise created by these larger fields.
One of the coolest things about MEG is that it can measure millisecond changes in brain activity. This can be combined with magnetic resonance imaging (MRI) to work out which areas of the brain are active. So scientists can essentially look at how the brain is functioning in real time. They can ask someone to perform a task and see exactly which part of the brain is controlling that task. In fact MEG was recently used to ‘read’ the minds of babies and work out that they are trying to talk well before they actually say their first words.
Heres’s a video of an MEG machine in action.
The Scientific Papers:
Hari and Salmelin. Magnetoencephalography: From SQUIDs to neuroscience: Neuroimage 20th Anniversary Special Edition. NeuroImage. 2012
Kuhl et al. Infants’ brain responses to speech suggest Analysis by Synthesis. PNAS. 2014.