General guidelines

Maintenance of MEG laborator

Laundry

The MEG laboratory is equipped with non-magnetic grey clothing and light rubber shoes for the participants. The laundry is collected to a separate basket and washed and dried in the Kärki 2nd floor maintenance room. Washing machine instructions can be found right next to the machines. The laundry can be washed by anyone doing MEG measurements.

Washing EEG caps   

The MEG-compatible EEG caps are washed with tap water and can be scrubbed with an electric toothbrush found in the laboratory. Good place to leave the caps to dry is in the 2nd floor maintenance room. The user should return the caps in their correct place in the MEG lab storage cabinet after drying.

Cleaning the lab

The measurement room floor is sweeped by professional cleaners every week or few times per week. However, the floor of the shielded room is not. Instead that is cleaned only by the users and MEG personnel. Therefore, everyone is responsible on acting as tidy as possible when using the laboratory. All users are also responsible for the tidiness of all the cupboards they are using. Also users should clean all the tapes and their residues after use from the surfaces.

Supplies

Every user should report to support personne when some supplies are about to run out. Such supplies may include electrodes, gel, ear tips, tape, ...

Helium Recycling (IHR)

Helium recycling sets limitations to MEG lab usage time, because we have to allow sufficient time between measurements. Usually this is overnight, but sometimes it is not enough. Timing of recycling is controlled by a software on DACQ computer called Scheduler. MEG data cannot be acquired when recycling is on. During recycling, the MEG gantry should be in the recycling position (indicated by blinking green light; see “Gantry position”). Main risk with IHR is that helium tanks get full -- thereafter, evaporated helium will escape to outer space, and recycling of that is no longer possible.

Using the Helium Recycling Scheduler

  1. Open the application from the Neuromag menu
  2. Select the date for making changes by double-clicking
  3. Write the new starting and finishing times to the window
  4. Split the day to several sessions if there is a break between reservations

When you are making a normal measurement:

  1. Make sure there is a single solid green light on the Helium recycling cabinet
  2. If you need to stop on-going recycling, click "Start MEG session" on DACQ computer or make required changes directly to the Scheduler
  3. Confirm positioning of the MEG gantry
  4. Confirm the colors in the Scheduler for upcoming days - report if going to reddish colors
  5. Prepare and conduct your experiment as planned
  6. Read the notifications during the session, if any, and take actions accordingly

When you leave the laboratory:

Check the reservation calendar.

  1. If there will be other measurements soon, clean up and leave the system as is
  2. If there will be a long break, turn on recycling using the Scheduler
  3. If you are the last user of the day, turn the gantry to liquification position (blinking green light in the position indicator) and select “Finish MEG Session” in Scheduler

Warnings / Notices

  1. Read the boxes issued by Scheduler, and take corresponding action.

Problems

  1. Call for help 

Troubleshooting, recovering and some pitfalls

Data Acquisition

Sometimes it happens that the MEG data acquisition halts due to a strange-looking error. 

First thing to do then is to capture the error message -- phone camera is great for this. Also try to write down what happened before the halt. We need these to track the problem.

Thereafter, you have two ways to deal with the error, the soft way and the hard way.

  1. The soft way -- RAP

This is faster, but may not always be enough.

  1. Quit Acquisition, saving settings if can and needed
  2. Open Menu / Neuromag / Maintenance / Restart Acquisition Programs
  3. A terminal opens and asks you if you want to restart -- answer "y" and hit Enter
  4. Wait until restart finishes and close the terminal
  5. Open Acquisition again. If there are still error messages, continue with option 2, below.
  6. Open Tools / Tuner and select File / Load tunings. Click "Load other" (go to next point) or "Load Default" (skip next point)
  7. Among tuning files (*.tnp) starting with a date (format “yymmdd”), open the freshest one.
  8. After Tuner has finished applying the new tuning settings, exit Tuner
  9. Check signal quality. If not ok, continue with option 2, below.

 

2. The hard way -- SCC reset

  1. Quit Acquisition, saving settings if needed
  2. Go to Electronics cabinet behind shielded room and find "System Control Card SCC"
  3. Shortly press the “reset” button until red lights (“Fail”) start appearing
  4. Wait until every card (SQC, SCC, FCC, SAM) shows steady green light (“Run”) only.
  5. Close the door and get back to DACQ.
  6. Continue with RAP (option 1, above).

If this does not help, ask help. For example logging out from the acquicition computer rarely helps except on very special cases.

If there's still no help, re-do and/or call for help. 

 

Delays

- Measure the delays of all your stimuli – if possible – before your first real experiment. This way you will avoid or at least minimize the unknown effects of different delays.

- It is known that visual stimuli might cause unwanted time jitters to your trigger data if not treated and handled properly. This is due to the refresh rate of the projector. 

- There are more detailed instructions how to do delay measurements in the "Files"-section of these instruction pages as a separate pdf-file.

Trigger channel 16

When using trigger channel 16, it might cause a peculiar effect to the STI101 collection channel in DACQ.  Instead of a positive trigger, it might show as a large negative trigger. This is due to how DACQ treats large binary values. This is a known bug in the data acquisition program which has been invetigated by experts. It can be corrected during data analysis (ask for instructions of how) or cheaply by avoiding the use of this channel.

SQC## (or something similar) connection problems

Every now and then Data Acquisition program might complain about connection issues to sqc## or something similar. This implies that the Data Acquisition cannot make connection to the Squid Controller cards. Often the only way to fix this is to reset SCC card in the machine area behind the shield room.  After resetting one has to run “Restart Acquisition Programs” routine which can be found in the Acquisition program folder. Also, afterwards one might have to load tunings in the Tuner.

Tuner hidden

Is the tuner hidden and DACQ complains about it when you try to start the program? Try pressing Alt+TAB to screen through the running programs. One might be the Tuner. If this does not help, next option might be doing RAP.

Camera surveillance

Screen showing the MEG participant looks funny

- If zoomed in, press right mouse button of the surveillance computer. Change screen settings and change them back. This should correct the situation. Hard way to do the same is to unplug and plug the surveillance camera electricity cable from the stimulus cabin.

- If the screen complains about connection issues, it might be that the power cord is not connected properly. Check that there is a green led glowing on the power cord's transformer.

Projector

The projector does not want to turn off? There should be an instruction sheet lying around on how to operate the projector. Normally, when the projector is turned "off", it actually goes to a standby mode. This is usually enough. When the standby mode starts, the fans might be running quite hard still for some time. If it is necessary to fully turn off the projector, let the machine run in standby mode for at least two minutes. Only then, remove the power cord from the wall to fully turn the machine off.

There has been couple of cases, when it has not been possible to change the input source from DVI2 to HDMI with the remote controlled. And not even from the projector directly. During this event, there might have been "No signal from DVI2" - or something similar - visible on the projected screen, although the stimulus computer screen has been in reality visible. In this case, the only solution so far to fix it has been to turn down the projector, after couple of minutes to remove the power cord and after that run the projector back up again.

HPI digitation

Remember to save HPI digitation in case the DACQ program freezes. Also record the save time when you did the saving. This will help you to find the correct digitation after possible restarting of the data acquisition program.

Disk space

To check how much room is left in the hard drive there is a specific program for it in the menu of the Acquisition program. However, this might not take in to account that the setup has an external data storage installed, also. So make sure you are measuring the space of the correct space.

He recycling on or not

Turn on if more than 3h break between experiments. One should also turn/flip the He dewar for recycling position during daytime breaks. Especially for overnight it is mandatory to flip it.

He recycling can also be turned on for shorter than 3h breaks. Then the dewar is not absolutely necessary to turn to recycling position, but it is recommended.

Can I disconnect the trigger cables inside stimulus cabin?

Only those cables coming from 4-button response device (input channels 11-14) should be always connected. All else can be disconnected if they are not part of your experiment.

How to use the internal communication system

The comm system has two different operation modes:

  1. Tangent mode. In this mode you keep “T” pressed down to speak to the shielded room. “T” is not pressed when you want to hear the sound from the shield room. This mode is turned on by pressing “T” for several seconds.
  2. Always on mode. In this mode you can hear what the sounds from the shield room and you can speak to the communication system without pressing anything. Note that in this mode the participant can hear everything you speak in the measurement room – albeit not necessarily very well. This mode is turned on by pressing “T” for only a short while.

When starting your experiment, the communication system should be turned to channel 11 by pressing “1” twice. The comm system is turned off by pressing “X”.

Ventilation effects

It is known that shielded-room ventilation will create artifacts to the MEG data. If they are a problem, turn off the ventilation for the duration of the experiment. But do remember to turn it back on, also. The ventilation machine is situated behind the MSR. There is a clear sign indicating the correct button for turning the ventilation on and off.

MEG chair doesn’t rise even after vigorous pumping

The chair is broken. Contact support personnel. If you see water on the floor below the chair, start drying it as soon as possible to prevent more mishaps.

Cibr-srv1 or cibr-srv2 does not work

During Summer and Autumn 2020 the cibr servers named cibr-srv1 and cibr-srv2 have been brought down. They have been replaced with servers named cibr1 and cibr2. Methods of accessing the servers have not changed, only the name.

Buzzing noise from the panel speakers

When using the panel speakers, there might be unwanted buzzing, electric noise in them. There are possibly some slight problems with the grounding of this audio system. But no clear fix for this has been found yet. However, the noise can be brought considerably down by playing with the audio cables going to and from the cleaning box (next to the stimulus computer) or sometimes the audio cables going to the panel speaker power supplies/amplifiers inside the stimulus cabin. Call support, if these don't help.

Measurement logs

The MEG lab has a log book where every user should mark what project and who has used the laboratory. Additionally, mark down all problems you had with the device. This way the support personnel can more easily follow the trend of problems people have had. Also, remember to use a good measurement log of your own. One example for a log can be found in https://cibr.jyu.fi/en/intranet/meg-lab-instructions/preparing-the-subject.