Enhanced frontal function in Parkinson's disease.
We investigated the role of dopamine in working memory by examining effects of withdrawing dopaminergic medication in patients with Parkinson's disease. Resistance to distraction during a delayed response task was abnormally enhanced in Parkinson's disease patients OFF medication relative to controls. Conversely, performance on a backward digit span test was impaired in these same Parkinson's disease patients OFF medication. Dopaminergic medication reinstated susceptibility to distraction and backward digit span performance, so that performance of Parkinson's disease patients ON medication did not differ from that of controls. We hypothesize that the enhanced distractor resistance and impaired backward digit span in Parkinson's disease reflects low dopamine levels in the striatum, and perhaps upregulated frontal dopamine levels. Dopaminergic medication may reinstate distractibility by normalizing the balance between striatal and prefrontal dopamine transmission.
Cools
R
R
Donders Institute for Brain, Cognition and Behaviour, Centre for Cognitive Neuroimaging, Radboud University Nijmegen Medical Centre, Department of Psychiatry, The Netherlands. roshan.cools@donders.ru.nl
Miyakawa
A
A
Sheridan
M
M
D'Esposito
M
M
D000368:Aged; D000369:Aged, 80 and over; D003072:Cognition Disorders / Q000150:complications / Q000503:physiopathology / Q000523:psychology; D005260:Female; D005625:Frontal Lobe / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D010300:Parkinson Disease / Q000150:complications / Q000503:physiopathology* / Q000523:psychology*; D011597:Psychomotor Performance / Q000502:physiology; D011930:Reaction Time / Q000502:physiology