Motor cortical beta activity (13-30 Hz) is a hallmark signature of healthy and pathological movement, but its behavioural relevance remains unclear. One reason for this is that slow, sustained changes in beta amplitude pre- and post-movement may not sufficiently summarize trial-wise dynamics in beta activity.
I will discuss recent approaches developed in the lab using high SNR magnetoencephalography (MEG) for laminar-specific analyses of beta signals including new approaches for obtaining better anatomical priors for MEG source reconstruction. I will present recent data on the laminar profile of average beta changes using some of these approaches, which support proposals about frequency specific channels for feedback and feedforward processing. However, the nature of high-power beta changes is transient, and dominated by punctate high-power beta events (bursts). Biophysical models and improved source reconstruction hints at a more complex laminar profile of transient beta events, with possible implication for theories of the laminar organization of these signals and their role in feedback/feedforward processing. These results indicate a necessary reappraisal of the functional role of sensorimotor beta activity in human cortex.