Authors:

Slabosz, A., Lewis, S. J. G., Smigasiewicz, K., Szymura, B., Barker, R.A. & OWEN, A. M.

Reference:

Year of publication:

2006

CBU number:

6395

Abstract:

In this study, the cognitive and neurochemical factors underlying learned irrelevance, one of the mechanisms thought to be responsible for attentional set-shifting deficits in Parkinson’s disease (PD), were investigated. In a visual discrimination learning task, the extent to which a target dimension was irrelevant prior to an extra-dimensional shift was varied. Twenty patients with PD and twenty-two healthy volunteers performed the task twice, with patients tested ‘on’ and ‘off’ L-dopa. The patients made more errors than controls in the condition where the target dimension was completely irrelevant prior to the extra-dimensional shift, but not where it was partially reinforced. Moreover, L-dopa had no effect on the patients’ task performance, despite improving their working memory. These results confirm that learned irrelevance is a significant factor in accounting for attentional set-shifting deficits in patients with PD, although unlike other executive impairments in this group, the phenomenon appears to be unrelated to their central dopaminergic deficit.