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Neuropsychologia. 2000;38(5):596-612.

Probabilistic learning and reversal deficits in patients with Parkinson's disease or frontal or temporal lobe lesions: possible adverse effects of dopaminergic medication.

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Department of Experimental Psychology, University of Cambridge, Downing Street, Cambridge, UK.


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.

[Indexed for MEDLINE]

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