Basal ganglia, dopamine and temporal processing: performance on three timing tasks on and off medication in Parkinson's disease.
A pervasive hypothesis in the timing literature is that temporal processing in the milliseconds and seconds range engages the basal ganglia and is modulated by dopamine. This hypothesis was investigated by testing 12 patients with Parkinson's disease (PD), both 'on' and 'off' dopaminergic medication, and 20 healthy controls on three timing tasks. In a seconds range (30-120 s) time production task, patients tested 'on' medication showed a significantly different accuracy profile compared to controls and when tested 'off' medication. However, no group or on vs off medication differences in accuracy were found on a time reproduction task and a warned reaction time task requiring temporal processing within the 250-2000 ms range. Variability was measured using the coefficient of variation, with the performance of the patient group on the time reproduction task violating the scalar property, suggesting atypical temporal processing mechanisms. The data suggest that the integrity of the basal ganglia is necessary for 'typical' time production in the seconds range as well as for time reproduction at shorter intervals. Exploratory factor analysis suggested that the time production task uses neural mechanisms distinct from those used in the other two timing tasks. The dissociation of the effects of dopaminergic medication and nature of task on performance in PD raises interesting questions about the pharmacological mediation and task-specificity of deficits in temporal processing.
Jones
Catherine R G
CR
Sobell Department of Motor Neuroscience and Movement Disorders, UCL Institute of Neurology, Queen Square, London, UK.
Malone
Tim J L
TJ
Dirnberger
Georg
G
Edwards
Mark
M
Jahanshahi
Marjan
M
D000161:Acoustic Stimulation / Q000379:methods; D000368:Aged; D000704:Analysis of Variance; D000978:Antiparkinson Agents / Q000627:therapeutic use; D001288:Attention / Q000187:drug effects / Q000502:physiology; D001479:Basal Ganglia / Q000503:physiopathology*; D003071:Cognition / Q000187:drug effects / Q000502:physiology; D004192:Discrimination, Psychological / Q000187:drug effects / Q000502:physiology; D004298:Dopamine / Q000378:metabolism; D005260:Female; D006801:Humans; D008297:Male; D008568:Memory / Q000187:drug effects / Q000502:physiology; D008875:Middle Aged; D009483:Neuropsychological Tests / Q000706:statistics & numerical data; D010300:Parkinson Disease / Q000188:drug therapy / Q000378:metabolism / Q000503:physiopathology*; D011597:Psychomotor Performance / Q000187:drug effects / Q000502:physiology*; D011930:Reaction Time / Q000187:drug effects / Q000502:physiology*; D013647:Task Performance and Analysis; D013998:Time Perception / Q000187:drug effects / Q000502:physiology*
D000978:Antiparkinson Agents; D004298:Dopamine