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Debra Titone

Publications and source records attributed to Debra Titone.

7 recordsLinked to original sources
PubMed2006

The misattribution of salience in delusional patients with schizophrenia.

INTRODUCTION: Delusions may arise from abnormalities in emotional perception. In this study, we tested the hypothesis that delusional schizophrenia patients are more likely than non-delusional schizophrenia patients and healthy participants to assign affective meanings to neutral stimuli. METHODS: Unpleasant, pleasant, and neutral words were randomly presented to three subject groups--patients with schizophrenia with prominent delusions, patients with schizophrenia without delusions, and healthy participants. Participants performed three tasks: one in which they decided whether a letter string was a word or a non-word (lexical decision) and two affective classification tasks in which they judged whether words were 1) neutral or unpleasant, or 2) neutral or pleasant. RESULTS: While there were no significant between-group differences in lexical decision performance, patients with delusions showed selective performance deficits in both affective classification tasks. First, delusional patients were significantly more likely than non-delusional patients and healthy participants to classify words as unpleasant. Second, delusional patients took significantly longer than both other groups to correctly classify neutral words in both affective classification tasks. CONCLUSIONS: Taken together, these findings suggest that delusions are associated with the explicit misattribution of salience to neutral stimuli.

Adult↗
PubMed2005

Hippocampal activation during processing of previously seen visual stimulus pairs.

Activity in the hippocampus is modulated by novelty detection, and by the processing of conjunctions between two stimuli. We investigated whether the hippocampus is activated by discrimination of stimulus-stimulus relationships in novel versus familiar pairs of visual stimuli in 15 healthy subjects using functional magnetic resonance imaging. Subjects were asked to recognize the previously rewarded stimulus in each case. We found significantly greater activation of the right hippocampus when discriminating previously seen compared with novel pairs of visual stimuli. This activation was evident in individual subjects and was not related to stimulus novelty, reward contingency, or task instruction. Right hippocampal activation during discrimination of previously seen pairs of objects was correlated with activity in the anteromedial thalamus, cingulate cortex, and contralateral hippocampus.

Adult↗
PubMed2004

Transitive inference in schizophrenia: impairments in relational memory organization.

Transitive inference (TI) describes a fundamental operation of relational (e.g., explicit) memory organization [Eichenbaum, H., Cohen, N.J., 2001. From Conditioning to Conscious Recollection: Memory Systems of the Brain. Oxford Univ. Press]. Here we investigate TI in schizophrenia (SZ), a neurocognitive disorder associated with explicit but not implicit memory dysfunction. SZ patients and healthy controls were trained on a series of learned discriminations that were hierarchically organized (A>B, B>C, C>D, and D>E). They were then tested on each training pair and two novel "inference" pairs: AE, which can be evaluated without consideration of hierarchical relations, and BD, which can only be evaluated by hierarchical relations. SZ patients and controls successfully learned the training pairs and correctly responded to the nonrelational AE pairs. However, SZ patients were less accurate than controls in responding to the relational BD pairs, consistent with the hypothesis that higher-level memory processes associated with relational memory organization are impaired in SZ. The results are discussed with respect to the relational memory model and candidate neuro-cognitive mechanisms of TI.

Adult↗
PubMed2004

Lexical competition and spoken word identification in schizophrenia.

Schizophrenia (SZ) is a disorder associated with dysfunction of the neural substrate involved in lexical processing, the superior temporal lobe (STL). We examined whether the detrimental effects of lexical competition on word identification are exaggerated in SZ. The results showed that SZ patients were less able than controls to identify words coming from high lexical competitor environments (i.e., high density and high frequency lexical neighborhoods). They did not differ from controls, however, in identifying words coming from low lexical competitor environments (i.e., low density and low frequency lexical neighborhoods). Further, when SZ patients misidentified high competitor words, the erroneously reported words were of a significantly higher frequency than those reported by controls when they misidentified high competitor words (i.e., the HF misidentification bias). Identification accuracy for high competitor words negatively correlated with amount of thought disorder, and the HF misidentification bias positively correlated with the lifetime frequency and severity of auditory hallucinations, the latter of which serving as presumed independent measures of STL dysfunction in SZ.

Adult↗
PubMed2004

Hippocampal activation during transitive inference in humans.

Studies in rodents have demonstrated that the integration and flexible expression of memories, necessary for transitive inference, depend on an intact hippocampus. To test this hypothesis in humans, we studied brain activation during the discrimination of a series of overlapping and non-overlapping arbitrary visual stimulus pairs. We report that transitive inference about overlapping pairs is associated with right anterior hippocampal activation, whereas recognition of non-overlapping stimulus pairs is associated with bilateral medial temporal lobe activation centered in the anterior parahippocampal gyrus. We conclude that immediate access to simple stimulus-stimulus relationships is mediated via the parahippocampal gyrus, whereas the flexible representation of memory requires the recruitment of the hippocampus.

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PubMed2002

Idiom processing in schizophrenia: literal implausibility saves the day for idiom priming.

Schizophrenia patients have difficulty processing nonliteral forms of discourse such as idiomatic expressions. We hypothesized that schizophrenia patients would show impaired idiom processing for literally plausible idioms (e.g., kick the bucket) but not for literally implausible idioms (e.g., be on cloud nine). Thirty-two patients and 36 controls listened to sentences containing literally plausible and implausible idioms and made lexical decisions about idiom-related or literal-related targets. Schizophrenia patients showed reduced priming for literally plausible idioms but intact priming for literally implausible idioms compared with controls. Both groups showed evidence of literal word priming. These results are consistent with the notion that schizophrenia patients make normal use of context under conditions that minimize the need for controlled processing.

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