MEG

Checking The MEG Before Recording

The importance of checking BEFORE the subject arrives

Once you have reserved a time slot for an experiment, it is FUNDAMENTAL that you plan to check the set-up of the lab for your experiment BEFORE (e.g. 30 min) the subject arrives. This will let you have the time to solve any problem by yourself or to call the MEG staff to solve it, and still have the possibility to carry on the experiment. Also, it will avoid involving the subject in troubleshooting operations, which may make her/him not feeling safe because something is not under control.

Preparations before each measurement session

  • Make sure that the MEG gantry is in the good position for your recording and that the LED on the back wall of the MSR is well green. If one of the LEDs are yellow, MEG gantry is not locked in secured position !!! This is dangerous for the MEG and for the subject. In this case, move again the MEG until the LED turns green again. See this slide on Gantry Movement operations for help. Do not hesitate to call the MEG staff for these operations if you never did them and/or you feel unsecure. Please note that every time the position of the gantry is changed between supine and upright (and viceversa), it will take at least 30 minutes for the sensors to work optimally again.
  • Make sure that all devices needed for your experiment are in place and ready to be used (e.g. eye tracker).
  • Load all the parameters of your experiment for data acquisition (see Chapter 4 'Experiment Preparation' in the Acquisition Software Manual). To check the signal in this phase, you do not need to load a subject (usually you do not have the subject's data yet).
  • Check the quality of the signals by browsing through all channels. See Chapter 5 'Acquisition' in the Acquisition Software Manual to get acquainted with the visualization options (channel selection, scales, filters etc.). See the Sensor Tuner User's Guide (also in the MEG room) for tuning the sensors if they are noisy. See the Troubleshooting Signal Quality page to read supplementary tips on how to cope with noisy sensors. You should spend some time with an experienced MEG user before your first pilot to get a sense of the quality of the signal and learn how to improve it.
  • Fill in the MEG notebook with key informations on your experiments that are crucial for tracking the daily use of the machine.