Magnetoencephalography (MEG) scans (top row) of 'slices' of a human brain, and comparison scans using Functional Magnetic Resonance Imaging (fMRI). Both sets of scans show network activity in the resting or 'default-mode' state. This network is only found at rest and disappears when the subject is given a task. The 'default-mode' network and its connection to various neurologial diseases and disorders is currently being intensively researched.The MEG scanner images the magnetic fields produced by the electrical currents resulting from neural activity within the brain. fMRI scanning measures the changes in blood flow resulting from the neural activity caused by brain stimulation or tasking.