title: Beat Keeping in a Sea Lion As Coupled Oscillation: Implications for Comparative Understanding of Human Rhythm.
abstract: Human capacity for entraining movement to external rhythms-i.e., beat keeping-is ubiquitous, but its evolutionary history and neural underpinnings remain a mystery. Recent findings of entrainment to simple and complex rhythms in non-human animals pave the way for a novel comparative approach to assess the origins and mechanisms of rhythmic behavior. The most reliable non-human beat keeper to date is a California sea lion, Ronan, who was trained to match head movements to isochronous repeating stimuli and showed spontaneous generalization of this ability to novel tempos and to the complex rhythms of music. Does Ronan's performance rely on the same neural mechanisms as human rhythmic behavior? In the current study, we presented Ronan with simple rhythmic stimuli at novel tempos. On some trials, we introduced "perturbations," altering either tempo or phase in the middle of a presentation. Ronan quickly adjusted her behavior following all perturbations, recovering her consistent phase and tempo relationships to the stimulus within a few beats. Ronan's performance was consistent with predictions of mathematical models describing coupled oscillation: a model relying solely on phase coupling strongly matched her behavior, and the model was further improved with the addition of period coupling. These findings are the clearest evidence yet for parity in human and non-human beat keeping and support the view that the human ability to perceive and move in time to rhythm may be rooted in broadly conserved neural mechanisms.
authors.affiliation: Long Marine Laboratory, Institute of Marine Sciences, University of California Santa Cruz Santa Cruz, CA, USA.
authors.forename: Andrew A
authors.initials: AA
authors.lastname: Rouse
authors.affiliation: Department of Psychology, Emory University Atlanta, GA, USA.
authors.forename: Peter F
authors.initials: PF
authors.lastname: Cook
authors.affiliation: Department of Psychological Sciences, University of Connecticut Storrs, CT, USA.
authors.forename: Edward W
authors.initials: EW
authors.lastname: Large
authors.affiliation: Long Marine Laboratory, Institute of Marine Sciences, University of California Santa Cruz Santa Cruz, CA, USA.
authors.forename: Colleen
authors.initials: C
authors.lastname: Reichmuth
keywords: music cognition and perception; neural oscillators; non-human models; rhythmic entrainment; sea lions; sensorimotor synchronization