The phase of slow wave oscillations couples with high gamma power in human electrocorticography during performed and imagined repetitive movements

Abstract High Gamma Band (HGB) and Slow Wave Oscillations (SWOs) have been identified as significant features in movement neurophysiology. HGB reflects local neuronal activity, while SWOs inform on the temporal characteristics of movement, especially during repetitive tasks. However, to date, they have mostly been studied separately, leaving details on their interaction largely unknown. Here, we looked at Phase Amplitude Coupling (PAC) to assess interactions between SWO phase and HGB power. We use a publicly-available electrocorticography (ECoG) dataset recorded during repetitive motor execution (ME) and motor imagery (MI) of hand and tongue movements. We found channels with significant SWO-HGB PAC for all subjects and tasks, distributed across multiple brain regions. In the sensorimotor cortex PAC occurred at specific coupling phases and was primarily observed during ME, while frontal and temporal regions exhibited similar PAC levels across ME and MI but lacked distinct preferred coupling phases. When training decoders for movement detection, PAC underperformed compared to SWOs or HGB; however, it showed a strong correlation with accuracy when single-channel SWOs were used as decoding feature, highlighting its potential for channel selection. Weaker correlations were found when PAC was compared to task-related HGB power increases, suggesting that these represent distinct neural features.