Electrophysiological Evidence for Sentence Comprehension - Wings

software was used. The caps employed standard electrode mounting based on 10-20
system. Recordings were referential and an average reference was used as suggested by,
for example, Picton et al. (2000).
Continuous EEG signal was recorded from each participant. The A/D conversion rate
was set on 1000 Hz with the resolution of 22 bits (maximal values for the equipment).
Notch filter was used (50 Hz). High pass filter was set on 0.1 Hz with 6 dB/octave slope
(minimal values) while the low pass filter was usually set on 70 Hz. However, sometimes
this value was lowered down to 50 Hz to account for the electromagnetic noise. The slope
also varied from 6 dB/octave to 12 Db/octave, depending on the recording conditions in
that moment. NeuroScan eye-blink reducing software based on linear derivation was used
to reduce eye-blinks. Movement artifacts or parts of the recordings too contaminated with
noise were rejected in order to obtain a clear data set.
The continuous EEG signal was epoched off-line. The epoched interval was -100 to 1000
ms around the trigger. The epoched signal was then averaged. After averaging, baseline
correction was performed with the pre-stimulus interval taken as the baseline. Finally, a
smoothing function (available in the Edit software) was applied if necessary, depending
on the high frequency noise still present in the average.
84