Schizophrenia Research Trends

In: Schizophrenia Research Trends ISBN 13: 978-1-60021-746-3Editor: Konstance V. Almann, pp. 137-161© 2008 Nova Science Publishers, Inc.Chapter VLATENT INHIBITION AND LEARNEDIRRELEVANCE PARADIGMS: A CONVENIENTWAY TO ASSESS INFORMATION PROCESSINGDEFICITS IN SCHIZOPHRENIAA. Orosz 1,2 , K. Cattapan-Ludewig 2 , G. Gal 3 , J. Feldon 11 Laboratory of Behavioral Biology, ETH Zürich, Switzerland2 University Hospital of Psychiatry, Bern, Switzerland3 Mental Health Epidemiology and Psychosocial Aspects of Illness, Gertner Institute forEpidemiology and Health Policy Research, Sheba Medical Center, Tel Hashomer, IsraelABSTRACTOne of the key features of schizophrenia is the inability to filter out irrelevant stimuliwhich consequently leads to stimulus overload. There are different paradigms which aim atinvestigating these deficient filter mechanisms; one of these is latent inhibition (LI). LI refersto the retardation of associative learning that normally occurs when the to-be-conditionedstimulus (CS) is previously preexposed without reinforcement. It is based on a form ofselective attention and reflects the ability of normal individuals to ignore irrelevant externaland internal stimuli. In schizophrenia, the LI effect is disrupted. This LI disruption is due tofaster learning of the CS-US (unconditioned stimulus) association which results in betterperformance of preexposed schizophrenic subjects compared to healthy controls. Because ofthis, attenuated LI has become an important tool to model cognitive and attentional deficits inschizophrenia.In recent studies a newly developed visual learned irrelevance (LIrr) paradigm has beenapplied. Learned irrelevance is yet another attentional paradigm related to latent inhibition. Incontrast to LI, in a LIrr test procedure both the CS and the US are preexposed in an unrelatedmanner. LIrr has been shown to retard associative learning even more than LI.