3.1 Sensorimotor timing/synchronization
Motor timing (Mauk2004.pdf)
Because movements involve changes in muscle length over time, motor control and timing are inextricably related. Most movements involve the coordinated activation of agonist muscles to initiate motion and antagonist muscles as a brake. These activations require accurate timing on the order of tens of ms. Indeed, pathologies that disrupt the timing between agonist and antagonist actions lead to dysmetric or inaccurate movements. Lesions of the cerebellum, for example, tend to delay the activation of antagonist muscles, which causes movements to be hypermetric or to overshoot (e.g., Hore et al. 1991). Cerebellar patients often display oscillating- like tremors during movements as they make a series of overshoots and corrections.
Numerous studies focusing on timing have made use of repetitive movements as their readout. In particular, Keele, Ivry, and others have used such movements as rhythmic tapping of the finger to pursue the hypothesis that the cerebellum is a general-purpose timer in the tens-to- hundreds-of- ms range (e.g., Ivry & Keele 1989). In the prototypical experiment, subjects are first asked to tap their finger in time with a metronome (say at 400-ms intervals). After a brief training period, the subject continues tapping without the metronome. The main dependent measure is variability in the intertap intervals. This and similar paradigms have been used as screens to find brain regions for which damage disturbs the timing of the taps. These and related findings are discussed in more detail below in the section on the cerebellum.
..... the failure of a neurological disorder — such as cerebellar injury — to affect the scalar property is taken to indicate that the affected structures are not essential for proper interval timing. Instead, the cerebellum might contain an internal model of the motor–effector system, so cerebellar damage could increase variability in motor and perceptual timing.