Probabilistic learning and reversal deficits in patients with Parkinson's disease or frontal or temporal lobe lesions: possible adverse effects of dopaminergic medication.
Three groups of patients with Parkinson's disease (PD) - mild, unmedicated (UPD), mild, medicated (MPD) and severe, medicated (SPD) - and patients with lesions of the frontal lobe (FLL) or temporal lobe (TLL) were compared with matched controls on the learning and reversal of probabilistic and two-pair concurrent colour discriminations. Both of the cortical lesion groups showed reversal deficits, with no increase in perseverative responding. The UPD group, although impaired on a spatial recognition task, showed intact discrimination learning and reversal; the MPD and SPD patients showed non-perseverative reversal impairments on both reversal tasks. Two hypotheses - based on disease severity and possible deleterious effects of medication - are offered to explain the reversal impairments of the PD patients and the results are discussed in terms of the role of dopamine in reward-based learning.
Swainson
R
R
Department of Experimental Psychology, University of Cambridge, Downing Street, Cambridge, UK. rs211@cus.cam.ac.uk
Rogers
R D
RD
Sahakian
B J
BJ
Summers
B A
BA
Polkey
C E
CE
Robbins
T W
TW
D000328:Adult; D000978:Antiparkinson Agents / Q000009:adverse effects* / Q000627:therapeutic use; D004192:Discrimination, Psychological / Q000502:physiology; D004827:Epilepsy / Q000601:surgery; D005260:Female; D005625:Frontal Lobe / Q000502:physiology* / Q000601:surgery; D006801:Humans; D007859:Learning Disabilities / Q000523:psychology*; D007980:Levodopa / Q000009:adverse effects* / Q000627:therapeutic use; D008297:Male; D015233:Models, Statistical; D017072:Neostriatum / Q000473:pathology; D010300:Parkinson Disease / Q000188:drug therapy / Q000523:psychology*; D010364:Pattern Recognition, Visual / Q000502:physiology; D012193:Reversal Learning / Q000502:physiology*; D013028:Space Perception / Q000502:physiology; D013702:Temporal Lobe / Q000502:physiology* / Q000601:surgery; D014796:Visual Perception / Q000502:physiology
D000978:Antiparkinson Agents; D007980:Levodopa