Cortical activations during paced finger-tapping applying visual and auditory pacing stimuli

In order to study neural systems which are involved in motor timing we used whole-brain functional resonance imaging while subjects performed a paced finger-tapping task (PFT) with their right index finger. During one conditi on, subjects were imaged while tapping in synchrony with tones separated by a constant interval (auditory synchronisation, AS), followed by tapping wi thout the pacing stimulus (auditory continuation, AC). In another condition , subjects were imaged while tapping in synchrony with a visual stimulus pr esented at the same frequency as the tones (visual synchronisation,VS) foll owed by a tapping sequence without visual pacing (visual continuation, VC). The following main results were obtained: (1) tapping in the context of vi sual pacing was generally more variable than tapping in the context of audi tory stimuli; (2) during all conditions, a fronto-parietal network was acti ve including the dorsal lateral premotor cortex (dPMC), M1, S1, inferior pa rietal lobule (LPi), supplementary motor cortex (SMA), the right cerebellar hemisphere, and the paravermial region; (3) stronger activation in the bil ateral ventral premotor cortex (vPMC), the left LPi, the SMA, the right inf erior cerebellum, and the left thalamus during both auditory conditions (AS and AC) compared to the visual conditions (VS and VC); (4) stronger activa tion in the right superior cerebellum, the vermis, and the right LPi during the visual conditions (VS and VC); (5) similar activations for the AS and AC conditions; but (6) marked differences between the VS and VC conditions especially in the dorsal premotor cortex (dPMC) and LPi areas; and (7) fina lly, there were no activations in the auditory and visual cortices when the pacing stimuli were absent. These findings were taken as evidence for a ge neral difference between the motor control modes operative during the audit ory and visual conditions. Paced finger tapping in the context of auditory pacing stimuli relies more on brain structures subserving internal motor co ntrol while paced finger-tapping in the context of visual pacing stimuli re lies on brain structures relying on the subserving processing or imaginatio n of visual pacing stimuli. (C) 2000 Elsevier Science B.V. All rights reser ved.