Current sources of the brain potentials before rapid eye movements in human REM sleep

In a previous study, we reported that rapid eye movements (REMs) in REM sleep were not preceded by the presaccadic positivity commonly observed before saccades in wakefulness but by a slow negative potential we called pre-REM negativity. In the present study, we examined current sources of the presaccadic positivity and pre-REM negativity using low resolution brain electromagnetic tomography (LORETA). Fourteen young healthy volunteers participated in the study. Brain potentials were recorded from 26 scalp sites and time-locked to the onsets of saccades and REMs during a visually triggered saccade task and natural nocturnal sleep. Current sources of the presaccadic positivity were estimated to be in the bilateral medial frontal gyrus, whereas those of the pre-REM negativity were estimated to be in the right amygdala, right parahippocampal gyrus, and left orbital gyrus. Different sources of these potentials give further support to the idea that different neural processes are responsible for saccades and REMs. Moreover, the findings that current sources of the pre-REM negativity were estimated to be in the limbic part of the brain suggests that this negativity might be associated with memory and emotional processing in REM sleep. (C) 2004 Elsevier B.V. All rights reserved.