The Elekta Neuromag Vectorview System
Below you'll find a short description of magnetometers and gradiometers, as well as our MEG sensor and EEG electrode layouts.
Technical description
Our Vectorview systems contains 102 magnetometers and 204 planar gradiometers. Magnetometers consist of a single coil which measures the magnetic flux perpendicular to its surface. Planar gradiometers consist of a "figure-of-eight"-type coil configuration. The measured signal is the difference between the two loops of the "eight", or the spatial gradient. There are two orthogonal planar gradiometers at each location. This arrangement is illustrated in the following figure (black: magnetometer; grey and white: two gradiometers).
attachment:MagsGrads.jpg
This is the whole sensor layout, including the sensor labels used by the Neuromag software:
attachment:SensorLayout.jpg
We routinely use a 70-electrode EEG set-up. This is the electrode layout:
attachment:ElectrodeLayout.jpg