Objective This work tests the specific role of the basal ganglia in the perceptual timing of auditory events. Previous studies of the perception of acoustically presented time intervals and rhythms at and above the millisecond level implicate areas distinct from auditory cortex (Cope et al, 2011). Recent studies investigating the effects of cerebellar degeneration (Grube et al, 2010a) and transcranial magnetic stimulation (Grube et al, 2010b) imply an obligatory role for the cerebellum in absolute, duration-based timing of perceptual events, but not in relative timing based on a regular beat. Functional imaging studies support the cerebellum as one constituent of a central timing network, but demonstrate preferential activation of the striatum for relative, beat-based timing (Grahn and Brett, 2007; Teki et al, 2011).

Method Six perceptual timing tasks were carried out to assess absolute duration discrimination for sub- and supra-second time intervals; detection of beat-based regularity and irregularity, detection of a delay within an isochronous sequence, and the discrimination of sequences with metrical structure. Test groups comprised of individuals with Multiple System Atrophy, a disorder in which similar pathology can produce clinical deficits associated with dysfunction of the cerebellum (MSA-C) or striatum (MSA-P (Burn and Jaros, 2001)), early symptomatic Huntington's disease (HD), and a control group of individuals with chronic autoimmune peripheral neuropathy.

Results All three patient groups exhibited impairments in performance in comparison with the control group for all of the timing tasks, and severity of impairment was overall associated with disease duration.

Conclusion Patients with Multiple System Atrophy and HD display global impairments in their ability to perform tasks of perceptual timing. These difficulties correlate with duration of symptoms and, in HD, severity of motor disease. HD caused the most striking deficit in both absolute and relative timing despite being a pure striatal disorder, unlike MSA which also affects the cerebellum. The study therefore demonstrates that the basal ganglia form an obligatory part of the brain timing network, and are necessary for both absolute and relative timing, irrespective of duration.