Reportage at the Neuroimaging research centre in Piti?Salp皻ri鋨e hospital in Paris, France. Magnetoencephalography (MEG) platform. MEG detects variations in the brain's magnetic field during various types of cerebral activity. It studies normal and abnormal brain function. Recording the magnetic field produced by neuronal currents requires ultra sensitive sensors called SQUIDs (Superconducting Quantum Interference Device). The 306 sensors spread over 102 areas allow both near and far magnetic fields to be measured, and the brain's deep structures to be 'seen'. The healthy patient wears an EEG (electroencephalography) cap allowing MEG and EEG to be combined.