Tempo mediates the involvement of motor areas in beat perception.

Increasing evidence shows that the neural circuits involved in beat perception overlap with motor circuitry even in the absence of overt movement. This study investigated effects of tempo on beat-based processing by combining functional magnetic resonance imaging with a perceptual timing paradigm where participants made simple temporal judgments about short rhythmic sequences. Of central interest were judgments about ambiguous test rhythms where the perceived direction of a timing deviation ("speeding up" vs. "slowing down") depended on the induction of an implied beat. Successful beat induction was reduced when the implied beat was at a slower tempo (1,500 ms) than when it was at a faster tempo (600 ms). Decreased beat induction was accompanied by decreased functional activity in the basal ganglia, premotor and supplementary motor regions, and thalamus. Findings support the conclusion that rhythms presented at a slow tempo reduce involvement of a striato-thalamo-cortico network in beat-based processing.