Acquisition tips
Averaging data
The acquisition software can average your data in real time and show the results as the experiment is running. The online averaged data will also be saved in a separate file. This option isn't as useful as you would think, as active shielding interferes with the results and makes them almost unusable. Therefore it is much better to average you data offline, using the saved raw data. However, to do so requires you to have specified all necessary details at the time of the recording. Changing or adding averaging details is difficult. For that reason it is highly recommended to fully specify all averaging information before running any experiment, and checking that everything is working correctly by using the online averager, even if its output is irrelevant.
HPI measurements
Before any recording can be made the locations of the HPI coils have to be measured by the MEG machine and compared to the locations measured by the 3D digitiser. This process requires the machine to be well tuned, as any noise at this point will result in unreliable locations. Therefore, this can be seen as a good test for the whole setup.
When the acquisition software doesn't recommend to accept the HPI locations, it is usually best to have a look at the raw sensor signal and see if any of the sensors is behaving badly.
Using continuous HPI
If using continuous head position indication (cHPI), acquire and save ~20s of data before turning on cHPI (ie before first stimulus). Otherwise MaxFilter has problems detecting bad channels (info from Matti Kajola).
Acoustic insulation of the MSR
At the moment the MSR is still quite leaky, acoustically. This means that the volunteer inside can hear a conversation going on in the control room, unless everyone is speaking very quietly. We hope that this issue will be solved soon, but for the time being we will just have to be careful.