Facilities

Synchronized cortical activity generates a the very weak magnetic field outside the scalp, that can be measured with MEG. These emerging magnetic fields are measured by means of superconducting quantum interference devices or SQUIDs. SQUIDs, consist of superconductive coils with a very small interruption (Josephson junction), which can be crossed by electrons because of quantum effects. Liquid helium maintains the system at -269ºC, ensuring that the SQUIDs are working in a superconducting state. The MEG system is contained in a magnetically shielded room, so that it remains isolated from external noise (e.g. the Earth’s magnetic field is about 100 million times higher than brain’s one).

Our MEG system is a 306-channel Elekta Neuromag® (Elekta Oy, Helsinki, Finland) contained in a magnetically shielded room provided by Vacuumschmelze, (Hanau, Germany). The system has 102 magnetometers and 204 planar gradiometers in a helmet-shaped array covering the entire scalp. A 3D-digitizer (FASTRACK; Polhemus, Colchester, Vermont, US) and four HPI coils enable the continuous monitoring of the head position inside the MEG system. Additionally, our MEG device has an integrated EEG-system consisting on 60 single-ended channels and 4 differential channels, so that EEG, EOG, EMG, and ECG signals can be recorded. This EEG-System includes non-magnetic, MEG-compatible EEG caps. Auditory, visual and somatosensory stimulation is also possible. The participant’s behavior inside the MEG can be video-recorded, as well as their online responses by using two independent optical-fiber-based digit-response pads.