067 Causal Communication Across the Electrode Manifold During Slow Oscillations

Abstract

Abstract Introduction The slow oscillation (0.5-1Hz, SO) is the most studied sleep waveform and reflects sleep homeostasis and is crucial for memory consolidation. It is not clear how SO causally affects brain networks. We used the effective connectivity technique to investigate causal information flow across the electrode manifold during the SO. Methods Night sleep EEG signals of 59 adult participants were recorded and visually scored into five sleep stages. We used three EEG channels for each region including frontal, central, parietal, and occipital. SOs were detected automatically and signals from one second before to one second after the SO’s troughs were used for estimating effective connectivity in SO and non-SO windows. Windowing technique and generalized partial directed coherence were employed to estimate causal information flow (CIF) between selected brain regions. The Linear mixed-effect (LME) method was used to model the peaks of the CIF based on different predictors including SO channel, source and sink of CIF, and distance between each of SO channel, source and sink regions. Results The results of CIF estimation showed two peaks of CIF about 250ms before and after the SO’s trough, but no difference between CIF in SO’s trough and non-SO windows. We found no effect of source and sink regions, and their distance on CIF (p-value > 0.05). However, distance between SO channel to source and sink region (p-value < 0.05) significantly predicted CIF. The coefficients of the LME model showed a direct effect of distance between SO channel to sink region and opposite effect of distance between SO channel to source region on CIF peaks. Conclusion The results showed there were significant changes of brain regions causal communication during SOs and these changes were affected by the distance of SO channel to sink and source region of CIF. Channels that are closer to the SO send more information and regions farther from the SO channel receive more information. Based on the results, we hypothesize that the SO brain networks are optimized to facilitate communication between regions that are far apart. Support (if any):