From neural activity to behavioral engagement: temporal dynamics as their "common currency" during music

The human cortex is highly dynamic as manifest in its vast ongoing temporal repertoire. Similarly, human behavior is also variable over time with, for instance, fluctuating response times. How the brain's ongoing dynamics relates to the fluctuating dynamics of behavior such as emotions remains yet unclear, though. We measure median frequency (MF) in a dynamic way (D-MF) to investigate the dynamics in both electroencephalography (EEG) neural activity and the subjects' continuous behavioral assessment of their perceived emotional engagement changes during five different music pieces. Our main findings are: (i) significant differences in the frequency dynamics, e.g., D-MF, of the subjects' behavioral engagement ratings between the five music pieces, (ii) significant differences in the, e.g., D-MF, of the music pieces' EEG-based neural activity, and (iii) there is a unidirectional relationship from neural to behavioral during the five music pieces as measured through correlation and Granger causality between their respective D-MF's. Together, we demonstrate that neural dynamics relates to behavioral dynamics through the shared fluctuations in their dynamics. This highlights the key role of dynamics in connecting neural and behavioral activity as their "common currency."