The infant EEG mu rhythm: Methodological considerations and best practices

• The EEG mu rhythm is reactive when performing and observing a specific action.
• Currently, methodological issues impede integrating infant mu rhythm findings.
• We outline methodological considerations for infant mu rhythm research.
• We propose guidelines to promote cross laboratory infant mu rhythm comparisons.
• Methodological topics include baseline, frequency bands, and experimental design.

The EEG mu rhythm, recorded from scalp regions overlying the sensorimotor cortex, appears to exhibit mirroring properties: It is reactive when performing an action and when observing another perform the same action. Recently, there has been an exponential increase in developmental mu rhythm research, partially due to the mu rhythm’s potential role in our understanding of others’ actions as well as a variety of other social and cognitive processes (e.g., imitation, theory of mind, language). Unfortunately, various methodological issues impede integrating these findings into a comprehensive theory of mu rhythm development. The present manuscript provides a review of the infant mu rhythm literature while focusing on current methodological problems that impede between study comparisons. By highlighting these issues and providing an in depth description and analysis we aim to heighten awareness and propose guidelines (when possible) that will promote rigorous infant mu rhythm research and facilitate between study comparisons. This paper is intended as a resource for developmental scientists, regardless of EEG expertise.