Schizophrenia Research Trends

150A. Orosz, K. Cattapan-Ludewig, G. Gal and J. FeldonLIrr retards associative learning more than LIBaker and Mackintosh (91) conditioned rats to lick water in the presence of a tone aftervarious types of preexposure: water alone (US), tone alone (CS), and uncorrelatedpresentations of tone and water. They found that the effect of unpaired CS and USpresentation was dramatically stronger in retarding subsequent conditioning than thepreexposure of either CS or US alone (92). There are further studies showing that theretardation of learning resulting from LIrr is stronger than that produced by LI (35;90;94;97).A potential explanation for the stronger learning retardation by LIrr is based on the theory ofcontext dependence of LI (92;96). It has been shown that the LI effect is context dependent(70). This means that if the preexposure and the conditioning take place in different contexts,LI might be reduced or even abolished (98). These contexts can be spatial (test room,environment) or temporal (time of day) (30). In a basic LI procedure the context changesbetween the preexposure and the conditioning phase, as in the latter phase the US ispresented, while in the former it is not (19). This change of context might contribute to LIreduction. In contrast, in LIrr paradigms the US is part of the context in which thepreexposure takes place (19) and it is also presented during conditioning. Thus, there is nocontext change what might produce a stronger LI effect. However, this would mean that LIrrand LI are the same phenomenon (19;99).LIrr paradigms might be more sensitive for individual variablesRegardless of whether LIrr constitutes a separate phenomenon, it is definitivelyworthwhile to introduce LIrr in psychiatric research. It is assumed that LIrr might producestronger effects than LI in humans as well (35) and can be therefore useful in situations whereLI tasks have produced results which are difficult to interpret (19). Moreover, Young et al.(97) revealed in a fMRI study that brain activity during a LIrr paradigm overlaps the regionswhich are activated by a LI paradigm. These findings indicate that results obtained by LIrrparadigms can be compared with those produced with LI paradigms (19) and might deliversupplementary or complementary insights into the underlying mechanisms.A NOVEL CONTINUOUS WITHIN-SUBJECT LIRR PARADIGMThe essential in a nutshellIn a handful recent studies (97;100) a new within-subject LIrr paradigm (developed byA.M. Young and coworkers) has been applied. The paradigm has been further adapted by G.Gal (101; 102). It is a short and simple computerized visual letter recognition task and istherefore manageable even for pathological groups. The pioneering properties of this new testare: first, it does not require a masking task, second, it is continuous, i.e. preexposure andconditioning have not to be performed separately, and third, it allows repeated measurements(102).