Magnetoencephalographic (MEG) recordings are a rich source of information about the neural dynamics underlying cognitive processes in the brain, with excellent temporal and good spatial resolution. In recent years there have been considerable advances in MEG hardware developments and methods. Sophisticated analysis techniques are now routinely applied and continuously improved, leading to fascinating insights into the intricate dynamics of neural processes. However, the rapidly increasing level of complexity of the different steps in a MEG study make it difficult for novices, and sometimes even for experts, to stay aware of possible limitations and caveats. Furthermore, the complexity of MEG data acquisition and data analysis requires special attention when describing MEG studies in publications, in order to facilitate interpretation and reproduction of the results. This manuscript aims at making recommendations for a number of important data acquisition and data analysis steps and suggests details that should be specified in manuscripts reporting MEG studies. These recommendations will hopefully serve as guidelines that help to strengthen the position of the MEG research community within the field of neuroscience, and may foster discussion in order to further enhance the quality and impact of MEG research.

How does acoustic degradation affect the neural mechanisms of working memory? Enhanced alpha oscillations (8–13 Hz) during retention of items in working memory are often interpreted to reflect increased demands on storage and inhibition. We hypothesized that auditory signal degradation poses an additional challenge to human listeners partly because it draws on the same neural mechanisms. In an adapted Sternberg paradigm, auditory memory load and acoustic degradation were parametrically varied and the magnetoencephalographic response was analyzed in the time–frequency domain. Notably, during the stimulus-free delay interval, alpha power monotonically increased at central–parietal sensors as functions of memory load (higher alpha power with more memory load) and of acoustic degradation (also higher alpha power with more severe acoustic degradation). This alpha effect was superadditive when highest load was combined with most severe degradation. Moreover, alpha oscillatory dynamics during stimulus-free delay were predictive of response times to the probe item. Source localization of alpha power during stimulus-free delay indicated that alpha generators in right parietal, cingulate, supramarginal, and superior temporal cortex were sensitive to combined memory load and acoustic degradation. In summary, both challenges of memory load and acoustic degradation increase activity in a common alpha-frequency network. The results set the stage for future studies on how chronic or acute degradations of sensory input affect mechanisms of executive control.

Significance: Attending and ignoring play fundamental roles in our everyday behavior in spatially and temporally fast-varying environments. Does focused attention to a specific stimulus adapt to these spatiotemporal dynamics? Using magnetoencephalography, we investigated the differential time courses of sensory encoding of two simultaneous, bottom-up rhythmic speech streams versus neural signatures of top-down spatial attention to one of the two streams. As expected, spatial attention modulated the power of ∼10-Hz (alpha) oscillations and their lateralization across the two cerebral hemispheres. Critically, this lateralization of alpha activity was modulated in temporal synchrony with the speech rate and predicted participants’ speech comprehension. Our results demonstrate that alpha activity acts as a spatiotemporal filter to control the read-out of attended and ignored sensory content.