NEURAL AND COGNITIVE STUDIES OF THOUGHT DISORDER IN SCHIZOPHRENIA

AUTOR(ES)
DATA DE PUBLICAÇÃO

2002

RESUMO

Thought Disorder (TD) is one of the most striking features of schizophrenia and is manifested clinically as abnormal speech. Despite being a core feature of the illness very little is known of its pathophysiology. One model based on a series of word-pair priming studies formulates TD as a consequence of hyper activation of the semantic network. However, as word-pair paradigms might not engage all the processes relevant to normal conversational speech, the use of sentences may be a more appropriate means of investigating language dysfunction in schizophrenia. Another model of thought disorder implicates impairments in executive functions. In this thesis the performance of patients with and without TD and healthy controls was compared on a battery of semantic priming tasks employing sentences (rather than word pairs). Executive Functions were also examined using a battery of computerised tasks. Finally, the neural correlates of a semantic decision task were investigated Functional Magnetic Resonance imaging. Results from the semantic tasks showed that although schizophrenic patients performed worse than controls there was no evidence that TD was associated with a hyperactivation of the semantic network. However, TD appeared to be associated with impairments in executive functions, although these were also evident to a lesser extent in patients who did not have TD. The FMRI data revealed that patients with TD showed differential activation relative to controls and patients without TD in brain language areas when processing sentences. These findings are discussed in relation to contemporary models of TD and with respect to schizophrenia. Overall the data confirm previous findings implicating impaired frontal lobe and executive functions in the pathophysiology of thought disorder in schizophrenia. However, the data did not support the idea that thought disorder is associated with is a fundamental problem in the semantic network.

ASSUNTO(S)

psiquiatria event-related fmri neuropsicologia experimental executive functions cognition psicologia cognitiva automatic and controlled attentional processes language schizophrenia event-related fmri técnicas de neuroimagem transtorno do pensamento em esquizofrenia thought disorder semantic processing

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