Table of Contents

EEG Preprocessing Pipeline for 7T/BrainMechR01

Concurrent EOG and high-impedance EEG was recorded with a Biosemi ActiveTwo with Actiview software (Minimitter, Bend, OR) 64-channel EEG system, in accordance with the international 10–20 system (Neymotin et al., 2020), located in an electromagnetically shielded room while participants performed the MGS task (described above). The task stimuli were presented on a computer 80 cm from the subject, and head position was maintained using a chin rest. Initial data were sampled at 512 Hz and down sampled to 150 Hz during preprocessing. Data were referenced to external electrodes corresponding to the mastoids due to their proximity to the scalp and low signal recording. An initial bandpass filter was set to 0.5–75 Hz. We used a revised version of an established protocol (Makoto Pipeline) for preprocessing compatible with EEGLAB (Delorme and Makeig, 2004). This protocol removes flatline channels (maximum tolerated flatline duration: 8 s), low-frequency drifts, noisy channels (defined as more than 5 standard deviations from the average channel signal), large amplitude artifacts, and incomplete segments of data (Jung et al., 2000; Hipp and Siegel, 2013). Deleted channels were replaced with interpolated data from surrounding electrodes. Continuous signals were divided into epochs, time-locked to stimulus onset (∼1–3 s). Data epochs were cleaned with an amplitude threshold of −500 to 500µV to exclude eye blinks. The resulting data were referenced to the average of all electrodes. As a final preprocessing step, independent component analysis (ICA) was performed to identify eye-blink artifacts and remove their contribution to the data. We confirm that gamma bursts are not present due to eye movement by plotting the spectrograms from the EOG channels.

Instructions to run preprocessing on 7T EEG data

Please refer to the LNCD Github Repository
Note: you need the hera function for the pipeline to run


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