Dopamine dependency of cognitive switching and response repetition effects in Parkinson's patients

Neuropsychologia. 2005;43(14):1990-9. doi: 10.1016/j.neuropsychologia.2005.03.024.


A group of people with Parkinson's disease and a group of matched controls were tested on a task involving a switch between perceptual dimensions. Patients were tested both 'on' and 'off' their normal medication cycles. Stimuli appeared in pairs for each trial, with each stimulus consisting of a color and a shape. One dimension of color and one of shape were mapped to each of two response keys. A cue was presented concurrently with each stimulus to indicate whether to respond on the basis of color or shape, following procedures developed by Hayes et al. [Hayes, A.E., Davidson, M.C., Keele, S.W., and Rafal, R.D. (1998). Toward a functional analysis of the basal ganglia. Journal of Cognitive Neuroscience, 10, 178-198]. Replicating previous literature, abnormally large switch costs were observed in patients who were off their normal medication cycles. A novel finding was that patients in the 'on' state demonstrated a slight reversal of switch costs. Also novel, reaction time (RT) costs associated with switching between response keys, and interactions between response switching and task switching were influenced predominantly by on-off dopamine manipulations. It is concluded that abnormal task switching costs and response repetition effects likely reflect impairments of activation and inhibition, and both effects are dopamine-dependent.

Publication types

  • Clinical Trial
  • Comparative Study
  • Research Support, N.I.H., Extramural

MeSH terms

  • Case-Control Studies
  • Cognition / drug effects*
  • Cognition / physiology
  • Discrimination Learning / drug effects
  • Dopamine / metabolism*
  • Dopamine Agents / administration & dosage
  • Female
  • Humans
  • Male
  • Middle Aged
  • Neuropsychological Tests
  • Parkinson Disease / drug therapy
  • Parkinson Disease / metabolism
  • Parkinson Disease / physiopathology*
  • Photic Stimulation / methods
  • Problem Solving / drug effects*
  • Problem Solving / physiology
  • Psychomotor Performance / drug effects
  • Reaction Time / drug effects


  • Dopamine Agents
  • Dopamine