Reliable quantification of neural entrainment to rhythmic auditory stimulation: simulation and experimental...

Objective.Entrainment has been considered as a potential mechanism underlying the facilitatory effect of rhythmic neural stimulation on neurorehabilitation. The inconsistent effects of brain stimulation on neurorehabilitation found in the literature may be caused by the variability in neural entrainment. To dissect the underlying mechanisms and optimize brain stimulation for improved effectiveness, it is critical to reliably assess the occurrence and the strength of neural entrainment. However, the factors influencing entrainment assessment are not yet fully understood. This study aims to investigate whether and how the relevant factors (i.e. data length, frequency bandwidth, signal-to-noise ratio (SNR), center frequency, and the constant component of stimulus-response phase-difference) influence the assessment reliability of neural entrainment.Approach.We simulated data for 28 scenarios to answer above questions. We also recorded experimental data to verify the findings from our simulation study.Main results.A minimal data length is required to achieve reliable neural entrainment assessment, and this requirement critically depends on the bandwidth and SNR, but is independent of the center frequency and the constant component of stimulus-response phase-difference. Furthermore, changing of bandwidth is accompanied by the change of SNR.Significance.The present study has revealed how data length, bandwidth, and SNR critically affect the assessment reliability of neural entrainment. The findings provide a foundation for the parameter setting in experiment design and data analysis in neural entrainment studies. While this study is within the context of rhythmic auditory stimulation, the conclusions may be applicable for neural entrainment to other rhythmic stimulations.