Posterior insular activity contributes to the late laser-evoked potential component in EEG recordings

Abstract

ObjectiveNociceptive activity in some brain areas has concordantly been reported in EEG source models, such as the anterior/mid-cingulate cortex and the parasylvian area. Whereas the posterior insula has been constantly reported to be active in intracortical and fMRI studies, non-invasive EEG and MEG recordings mostly failed to detect activity in this region. This study aimed to determine an appropriate inverse modeling approach in EEG recordings to model posterior insular activity, assuming the late LEP (laser evoked potential) time window to yield a better separation from other ongoing cortical activity. MethodsIn 12 healthy volunteers, nociceptive stimuli of three intensities were applied. LEP were recorded using 32-channel EEG recordings. Source analysis was performed in specific time windows defined in the grand-average dataset. Two distinct dipole-pairs located close to the operculo-insular area were compared. ResultsOur results show that posterior insular activity yields a substantial contribution to the latest part (positive component) of the LEP. ConclusionsEven though the initial insular activity onset is in the early LEP time window,modelingthe insular activity in the late LEP time window might result in better separation from other ongoing cortical activity. SignificanceModeling the late LEP activity might enable to distinguish posterior insular activity.