MEG Session Checklist

Step by step MEG Session checklist

Author: Maitha Al Shaali ma6895@nyu.edu

Scheduling A Session

• Confirm the session date and time with the participant using your preferred method (e.g., Sona, Calendly), and cross-check CTPSS to avoid conflicts with other MEG sessions.
• Create and send a Google Calendar invite to the participant.
• Book the session on CTPSS, including a ~30-minute buffer before and after. Do not include the participant in this booking.
• Email the participant the study requirements, consent form, and any pre-experiment surveys (if applicable).

Before Participant Arrival

• Disinfect surfaces (bed, helmet), HPI-coils (gently), and earphones using disinfectant wipes.
• Place clean bedsheet, pillow cover and new earphone covers.
• Cut 15 pieces of tape (~3-inches in length) for attaching HPI coils.
• Switch on EyeLink and Eye-tracking computer (if applicable).
• Test speakers, microphones, response boxes, and screen inside Magnetically Shielded Room (MSR).
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• Call security to request switching off all devices until the session is completed.
• If the participant wears hijab:
  • Request all male researchers to leave the lab for the session duration.
  • Put up the “ladies only” sign on the outside of the lab door.
  • Set up the divider near the door.

MSR Preparation

• Ensure that the Marker Box is switched on.
• Switch on the ProPixx screen from the stimulus computer.
• Test the speaker and microphone by asking the participant if they are able to hear you.
• Test the eye-tracker calibration (if applicable).
• SWITCH OFF THE HEATER

Participant Preparation

• Welcome the participant to the lab and confirm their name and/or NetID.
• Confirm or remind the participant about the consent form and any pre-experiment surveys (if applicable).
• Briefly explain the process and requirements for their participation.
• Confirm that the participant does not have any non-removable metal on their body.
• If the participant wears glasses, ask for their prescription and provide MEG-compatible glasses.
• Ask the participant to change into the scrubs provided and remove all metals (smart watches, jewelry, hair accessories, etc.).
• Set all devices to Airplane Mode (phones, smart watches).
• Briefly explain the laser scan process.
• Equip the participant with a tight-fitting cap to smooth their head shape.
• Place brace around participant's neck covered with paper towel for hygiene
• Draw the Marker points on the participants head with a felt-tip marker.
• Ask the participant to close their eyes and remain still during the laser scan.
• Conduct the laser scan (sweeps and points).
• Guide the participant to the MSR.
• Explain the process of attaching HPI coils and the study setup (bed, screen, eye-tracker).
• Attach the coils to the participant’s head using the guide on the wall and the cable labels.
• Help the participant lie down carefully on the bed, ensuring the coils do not detach or shift.
• Equip the participant with earphones.
• Provide the participant with the leg pillow and blanket for comfort.
• Switch off the lights and shut the MSR door.

MEG Recording

At the MEG Main Computer:

• Open MEGLaboratory: click Acquire > Autotuning > OK and wait for the autotuning process to complete.
• Click Acquire > MEG Measurement > Sensor Check and perform for 30 secs to 1 minute.
• While waiting, fill in subject details (e.g., “sub-007”).
• Create the subject folder and copy/paste the folder path so that the data is saved correctly.
• Disable Sensor Check button
• Once signals are stable, click Lock.
• Wait for Lock to complete and for the signals to stabilise again.
• Take a marker measurement: click MEG Measurement > Marker Measurement > Start.
• After the process is complete, ensure accuracy values are around 99.90% or above.
• Ensure the screen is displaying the experiment instructions and that the participant is ready to begin the task.
• Start recording: click Continuous Mode > Start > Start Acquisition.
• During the session, take note of any signal abnormalities, participant movement, or interruptions with timestamps.

After MEG Session

• Stop recording: click Continuous Mode > Abort.
• Save the .con file to the participant folder.
• Take a second marker measurement: click Acquire > MEG Measurement > Marker Measurement.
• Once the MEG measurement is complete, click Unlock.
• Switch on the lights and open the MSR door.
• Assist the participant in sitting up and carefully remove the HPI coils.
• Guide the participant back to the laser scan room and instruct them to change back into their clothes and collect all belongings.
• Switch the heater back on.
• Provide the participant with compensation (if applicable).

After Participant Leaves

• Switch Marker Box off.
• Remove and stow used bedsheets and pillow covers in the laundry basket, and used earphone covers in the bin.
• Disinfect MSR surfaces (bed, helmet), HPI coils (gently), and earphones using disinfectant wipes.
• Call security to inform them that the session is complete (if finished early).
• Replace the 15 pieces of tape - ready for the next experiment

Saving The Data

Experiment Data

• At the Stimulus Computer, use the hard drive “EXTREME SSD” to save the data and transfer to the Laser Scan computer.
• Open the project folder, select and upload the following files to the hard drive:
  • sub-007.edf
  • trigger_log_s011_YYYYMMDD_000000.txt
  • sub-007-vcp.mat

Laser Scan Data

• At the laser scan computer, create a folder with the participant ID (e.g. “sub-007”).
• Save raw laser scan data as “sub-007_laser-scan”.
• Apply the smoothing filter: View > Basic Surface > Save as: “sub-007_basic-surface”
• Save files to the subject folder: Export > Basic Surface > Export stylus points as well. Save as: “sub-007_stylus-points”
• At the Laser Scan Computer, open the project folder, select and upload the following files to the hard drive:
  • sub-007_laser-project
  • sub-007_basic-surface
  • sub-007_stylus-points

MEG Data

• Use the hard drive “EXTREME SSD” to save the data and transfer from MEG Main PC to the Laser Scan computer.
• At the MEG Main PC, open the “sub-007.con” file and click Edit > Noise Reduction (R) > save as “sub-007_denoised.con”.
• At the MEG Main PC, open the project folder, select and upload the following files to the hard drive:
  • YYMMDD-1.mrk
  • YYMMDD-2.mrk
  • sub-007.con
  • sub-007_denoised.con

• Safely eject EXTREME SSD.

Uploading Data to NYU Box:

• In the project folder on NYU Box, create 3 sub-folders, name them:
  • "derivatives" for Experiment Data
  • "laserscan" for Laser Scan Data
  • "meg" for Experiment Data

• From the hard drive, select and upload all files to their respective folders.

The “derivatives” folder should contain the following files:

• sub007.edf
• trigger_log_s011_YYYYMMDD_000000.txt
• sub-007-vcp.mat

The “laserscan” folder should contain the following files:

• sub-007_laser-project
• sub-007_basic-surface
• sub-007_stylus-points

The “meg” folder should contain the following files:

• YYMMDD-1.mrk
• YYMMDD-2.mrk
• sub-007.con
• sub-007_denoised.con