title: Paced finger-tapping abnormalities in bipolar disorder indicate timing dysfunction.
abstract: OBJECTIVE
  Theoretical and empirical evidence suggests that impaired time perception and the neural circuitry contributing to internal timing mechanisms may contribute to severe psychiatric disorders, including mood disorders. The structures that are involved in subsecond timing, i.e., cerebellum and basal ganglia, have also been implicated in the pathophysiology of bipolar disorder. However, the timing of subsecond intervals has infrequently been studied in this population.
  
  
  METHODS
  Paced finger-tapping tasks have been used to characterize internal timing processes in neuropsychiatric disorders. A total of 42 bipolar disorder patients (25 euthymic, 17 manic) and 42 age-matched healthy controls completed a finger-tapping task in which they tapped in time with a paced (500-ms intertap interval) auditory stimulus (synchronization), then continued tapping without auditory input while attempting to maintain the same pace (continuation). This procedure was followed using the dominant index finger, then with alternating thumbs.
  
  
  RESULTS
  Bipolar disorder participants showed greater timing variability relative to controls regardless of pacing stimulus (synchronization versus continuation) or condition (dominant index finger versus alternating thumbs). Decomposition of timing variance into internal clock versus motor implementation components using the Wing-Kristofferson model showed higher clock variability in the bipolar disorder groups compared to controls, with no differences between groups on motor implementation variability.
  
  
  CONCLUSIONS
  These findings suggest that internal timing mechanisms are disrupted in bipolar disorder patients, independent of symptom status. Increased clock variability in bipolar disorder may be related to abnormalities in cerebellar function.
authors.affiliation: Department of Psychological and Brain Sciences, Indiana University, 1101 East Tenth Street, Bloomington, IN 47405, USA.
authors.forename: Amanda R
authors.initials: AR
authors.lastname: Bolbecker
authors.forename: S Lee
authors.initials: SL
authors.lastname: Hong
authors.forename: Jerillyn S
authors.initials: JS
authors.lastname: Kent
authors.forename: Jennifer K
authors.initials: JK
authors.lastname: Forsyth
authors.forename: Mallory J
authors.initials: MJ
authors.lastname: Klaunig
authors.forename: Emily K
authors.initials: EK
authors.lastname: Lazar
authors.forename: Brian F
authors.initials: BF
authors.lastname: O'Donnell
authors.forename: William P
authors.initials: WP
authors.lastname: Hetrick
mesh_terms: D000328:Adult; D001307:Auditory Perception / Q000502:physiology; D001714:Bipolar Disorder / Q000503:physiopathology*; D016022:Case-Control Studies; D002531:Cerebellum / Q000502:physiology* / Q000503:physiopathology; D005260:Female; D005385:Fingers / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D008959:Models, Neurological; D009068:Movement / Q000502:physiology*; D011597:Psychomotor Performance / Q000502:physiology*; D013998:Time Perception; D055815:Young Adult