a1 Faculty of Psychology and Neuroscience, Department of Neuropsychology and Psychopharmacology, Maastricht University, Maastricht, The Netherlands
Learned irrelevance (LIrr) refers to a reduction in associative learning after pre-exposure of the conditioned and unconditioned stimulus in a non-contingent fashion. This paradigm might serve as a translational model for (pre)attentive information processing deficits in schizophrenia. This is the first study to investigate the event-related potentials (ERPs) of a within-subject LIrr paradigm in humans. Furthermore, the effects of the muscarinic M1 antagonist biperiden on LIrr were assessed. As expected, LIrr was found to be intact in young healthy volunteers after placebo. Furthermore, in the placebo condition P3b latency was decreased for target stimuli, which were pre-cued. This suggests that the predictability of the occurrence of these stimuli is mainly reflected by this ERP component. Biperiden had no effect on the behavioural LIrr measures, although prolonged reaction times were evident. Biperiden increased the N1 amplitude of the pre-exposed predictor letters, suggesting an effect of this drug on early perceptual processing. In conclusion, the within-subject paradigm used in the current study in combination with electroencephalography can reveal brain mechanisms involved in LIrr. M1 antagonism did not affect LIrr performance but seemed to influence early information processing.
(Received July 19 2011)
(Reviewed August 23 2011)
(Revised August 25 2011)
(Accepted September 30 2011)
(Online publication November 18 2011)
c1 Address for correspondence: I. Klinkenberg, M.Sc., Faculty of Psychology and Neuroscience, Department of Neuropsychology and Psychopharmacology, Maastricht University, PO Box 616, 6200 MD Maastricht, The Netherlands. Tel.: +31 (0)43 3884217 Fax: +31 (0)43 3884560 Email: email@example.com