Monday, February 10th, 2014, 3pm, KL 232

Groove is in the motor system, and other rhythmic musings

Michael Hove, Ph.D. Harvard Medical School

In this talk, I will present some recent work on rhythm and timing. The perception of rhythm and timing relies on motor system activity. Auditory-motor links could explain some music’s ability to induce movement – a musical quality called Groove. Using Transcranial Magnetic Stimulation (TMS), we examined the effects of groove music on motor system activity. Passive listening to high-groove music modulated motor system excitability, whereas low-groove music and a noise control had no effect. High-groove songs had more spectral flux (i.e., energy) in bass frequencies. By musical convention, bass-instruments often carry rhythmic or timing information (whereas higher pitches typically carry the melody). We examined the connection between bass-frequencies and timing in a follow-up EEG study. Mismatch negativity (MMN) responses were larger for unexpected timing changes of lower-pitched than higher-pitched tones, indicating better timing encoding for lower-pitched tones. Results from a model of the auditory periphery suggest that dynamics of the cochlea in the inner ear contribute to this effect, and that these musical conventions likely arise from basic auditory physiology. I will conclude with projects on applications of rhythmic stimulation. We showed that an interactive metronome improves gait in Parkinson’s Disease. Finally, rhythmic drumming has long been used to induce trance states of consciousness. Using fMRI, we examined the brain network configurations of shamans who used repetitive drumming to enter a trance.