Update Reference Channel

This section will guide you through the process of updating the reference channel in your EEG data using MNE-Python. The DSI-24 system uses Pz as the hardware reference point, but it is often beneficial to re-reference to a more common standard, such as Linked Ears (average of A1 and A2 electrodes).

The raweegdata object is assumed to be your loaded EEG data, as shown in the previous sections. See MNE Load for more details on loading EEG data.

Re-Referencing EEG Data

This code will change the reference to a more commonly used Linked Ear Reference, which is calculated as the average of the A1 and A2 electrodes.

Update Reference Channel

ref_channels_for_average = ['EEG A1-Pz', 'EEG A2-Pz'] # Insert in this List the Channels you want to reference
raweegdata.set_eeg_reference(ref_channels=ref_channels_for_average)
print('Available channels (After Re-Referencing):', raweegdata.ch_names)

This code sets the original EEG Data to a new reference which is Linked Ears (Average of A1 and A2). Make sure the channels are spelled correctly and exist in your EEG Data.

Renaming Channel References to Reflect Linked-Ears (LE) Average

Even after the EEG Data has been Re-Referenced to the average of the A1 and A2 electrodes (Linked Ears, or LE), the channel names ending with ‘-Pz’ still persist. The next part of the code will change such names ending with ‘-Pz’ to ‘-LE’ and reflect the changes visually.

Rename Reference Channels

# For loop that renames every channel ending with '-Pz' to '-LE' (Linked Ears, '-A1/A2 Average')
renamed_channels = {}
for ch_name in raweegdata.ch_names:
    if '-Pz' in ch_name:
        renamed_channels[ch_name] = ch_name.replace('-Pz', '-LE')
    elif ch_name == 'Pz': # Assuming 'Pz' was the channel that was originally being referenced
        renamed_channels[ch_name] = 'Pz-LE' # Now 'Pz' is referenced to Linked Ears (LE)

# Apply the new channel names to the object
raweegdata.rename_channels(renamed_channels)
print('Available channels (After Renaming):', raweegdata.ch_names)

It may be preferable to rename the channels as the base channel name, regardless of reference as several methods in MNE will require valid 10-20 channel names. This code will rename the channels ending with ‘-Pz’ to ‘-LE’ (Linked Ears) and reflect the changes visually.