EEG Remarking Status Channel

“Remarking” is part of the preprocessing pipeline. For more see EEG Preprocessing Pipeline for 7T/BrainMechR01

The BioSemi device used in EEG at Loeffler records in 24-bits on the Status Channel (16 available for task). Matlab and python read in 32-bits. Task “trigger”/“TTL” values in the Status channel are read in offset from what is sent/intended-to-be-recorded. More info about the BDF format on fieldtriptoolbox's page, and for more on bit masking, see mne python's read_bdf documentation. Also see BESA's note on "negative logic" (maybe why our status channel has negative values).

Additionally, tasks may send more information than desired for analsyis. E.g. we may want to group all prep events into a single type but the task sends different triggers for various types of prep events. Remarking would collapse all of these (say values 100-150) into a single event code (say 100).

TODO: example matlab code? link to github functions (fix_stim_channel).