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Key Words: schizo phre nia, thought dis or ders, lan guage, con text pro cess ing, N400, late pos i tive com po nentCan J Psy chi a try, Vol 48, No 9, Oc to ber 2003 W 615Ob jec tive: The aim of this study was to test the hy poth e sis that re in forc ing the struc tur ing of ver bal ma te rial may bring about an im prove ment in contextualization pro cesses in patients with for mal thought-disordered schizo phre nia. Method:A to tal of 38 schizo phre nia pa tients with for mal thought dis or ders and 24 matched healthy con trol sub jects per formed 2 lex i cal de ci sion tasks, in volv ing 2 lev els of con tex tual struc tur ing (with 16.7% and 33% of re lated words, re spec tively). The eventre lated po ten tials, N400 and late pos i tive com po nent (LPC), and be hav ioural vari ables ( reaction times and er ror per cent ages) were an a lyzed. Re sults:A con text-structuring ef fect was ob served on LPC, but not on N400. In sub jects with schizo phre nia, the N400 anom a lies (that is, in crease in am pli tude for the re lated words and re duc tion of the N400 ef fect) per sisted in both con text-structuring con di tions. Sim i larly, a re duc tion in LPC am pli tude for the un re lated word cat e gory, as well as a decrease in the LPC ef fect, was ob served in these pa tients. Con clu sions:The schizo phre nia pa tients with for mal thought dis or ders did not ben e fit from the struc tur ing of the con text to im ple ment con text in te gra tion strat e gies. This def i cit ap pears to be sta ble. The re sults are dis cussed within the frame work of a pre vi ously published model of lan guage com pre hen sion.(Can J Psy chi a try 2003;48:615-623) In for ma tion on au thor af fil i a tions ap pears at the end of the ar ti cle. Clin i cal Im pli ca tions· The im pair ment of the in te gra tive pro cesses that are in volved in the pro cess ing of con text is con firmed in pa tients with thought-disordered schizo phre nia. · This def i cit ap pears to be sta ble and does not ben e fit from any cog ni tive remediation. · The hy poth e sis pro posed in this ar ti cle-that the pre dic tive pro cesses are pre served while the in te gra tive contextualization pro cesses are im paired-makes ef forts at cog ni tive re ha bil i ta tion con ceiv able. Lim i ta tions· The pro posed hy poth e sis; namely, that there is a def i cit in the in te gra tive con text-pro cess ing strat e gies in schizo phre nia patients and that the pre dic tive strat e gies are pre served will have to be tested di rectly. · The ecologic na ture of the in ves ti gated pro cesses will have to be con firmed in sit u a tions closer to that of nat u ral lan guage (for ex am ple, us ing a phrasal con text).

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