Interaction among musical, cerebral and autonomous rhythms

Several studies have documented beneficial effects of music. There is considerable interest in determining how these effects come about. We have previously shown an overall increase in coherence between EEGs and autonomic variables such as heart rate, blood pressure and respiration when subjects listed to songs. In the present study we determined the coherence among different locations of EEG, heart rate and respiration with envelopes of the songs that the subjects listened to. The data used in this paper were ECG, EEGs (6 locations), finger plethysmograph blood pressure and respiration recorded from 14 healthy subject. To measure synchronization, coherence, i.e. magnitude squared coherence (MSC) was computed. In order to determine coherence of EEGs and songs with other variables with lower frequency content, we used the envelopes of the EEGs and songs, i.e. computed coherences in the low frequency components of these signals. Similar to coherencies between EEG and autonomic rhythms, we observed an overall increase in coherence among different locations of EEG. In addition, different levels of synchronization of heart rate, respiration, systolic and diastolic blood pressures and brain electrical response recorded by surface EEGs, were observed with different type of songs. Our results showed that slow tempo song had the largest impact in making all these variables synchronized to its envelope profile, and when the tempo of song was fast this level of synchronization was significantly smaller. During listening to music, the synchronization, among EEGs was more significant in T3 (with other EEGs), but the synchronization with songs' envelope profile was more significant in T4. Also, songs with expected similar cognitive effects produced higher synchronization levels of the all measured physiological variables with their envelope profiles. These results show the important role of tempo and cognition of songs in synchronizing different physiological variables with songs' envelopes and in suggesting interdependencies among multiple cortical areas.