Les réseaux du langage et des hallucinations

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Spécialisation hémisphérique pour le langage dans la schizophrénie (étude en imagerie par résonance magnétique fonctionnelle)

PARIS-BIUSJ-Thèses (751052125) / SudocPARIS-BIUSJ-Physique recherche (751052113) / SudocSudocFranceF

Social cognition in schizophrenic patients: The effect of semantic content and prosody in the comprehension of emotional discourse

International audienceBACKGROUND The recognition of the emotion expressed during conversation relies on the integration of both semantic processing and decoding of emotional prosody. The integration of both types of elements is necessary for social interaction. No study has investigated how these processes are impaired in patients with schizophrenia during the comprehension of an emotional speech. Since patients with schizophrenia have difficulty in daily interactions, it would be of great interest to investigate how these processes are impaired. We tested the hypothesis that patients present lesser performances regarding both semantic and emotional prosodic processes during emotional speech comprehension compared with healthy participants. METHODS The paradigm is based on sentences built with emotional (anger, happiness, or sadness) semantic content uttered with or without congruent emotional prosody. The study participants had to decide with which of the emotional categories each sentence corresponded. RESULTS Patients performed significantly worse than their matched controls, even in the presence of emotional prosody, showing that their ability to understand emotional semantic content was impaired. Although prosody improved performances in both groups, it benefited the patients more than the controls. CONCLUSION Patients exhibited both impaired semantic and emotional prosodic comprehensions. However, they took greater advantage of emotional prosody adjunction than healthy participants. Consequently, focusing on emotional prosody during carrying may improve social communication

A shared neural substrate for mentalizing and the affective component of sentence comprehension.

Using event-related fMRI in a sample of 42 healthy participants, we compared the cerebral activity maps obtained when classifying spoken sentences based on the mental content of the main character (belief, deception or empathy) or on the emotional tonality of the sentence (happiness, anger or sadness). To control for the effects of different syntactic constructions (such as embedded clauses in belief sentences), we subtracted from each map the BOLD activations obtained during plausibility judgments on structurally matching sentences, devoid of emotions or ToM. The obtained theory of mind (ToM) and emotional speech comprehension networks overlapped in the bilateral temporo-parietal junction, posterior cingulate cortex, right anterior temporal lobe, dorsomedial prefrontal cortex and in the left inferior frontal sulcus. These regions form a ToM network, which contributes to the emotional component of spoken sentence comprehension. Compared with the ToM task, in which the sentences were enounced on a neutral tone, the emotional sentence classification task, in which the sentences were play-acted, was associated with a greater activity in the bilateral superior temporal sulcus, in line with the presence of emotional prosody. Besides, the ventromedial prefrontal cortex was more active during emotional than ToM sentence processing. This region may link mental state representations with verbal and prosodic emotional cues. Compared with emotional sentence classification, ToM was associated with greater activity in the caudate nucleus, paracingulate cortex, and superior frontal and parietal regions, in line with behavioral data showing that ToM sentence comprehension was a more demanding task

Disentangling the brain networks supporting affective speech comprehension.

International audienceAreas involved in social cognition, such as the medial prefrontal cortex (mPFC) and the left temporo-parietal junction (TPJ) appear to be active during the classification of sentences according to emotional criteria (happy, angry or sad, [Beaucousin et al., 2007]). These two regions are frequently co-activated in studies about theory of mind (ToM). To confirm that these regions constitute a coherent network during affective speech comprehension, new event-related functional magnetic resonance imaging data were acquired, using the emotional and grammatical-person sentence classification tasks on a larger sample of 51 participants. The comparison of the emotional and grammatical tasks confirmed the previous findings. Functional connectivity analyses established a clear demarcation between a "Medial" network, including the mPFC and TPJ regions, and a bilateral "Language" network, which gathered inferior frontal and temporal areas. These findings suggest that emotional speech comprehension results from interactions between language, ToM and emotion processing networks. The language network, active during both tasks, would be involved in the extraction of lexical and prosodic emotional cues, while the medial network, active only during the emotional task, would drive the making of inferences about the sentences' emotional content, based on their meanings. The left and right amygdalae displayed a stronger response during the emotional condition, but were seldom correlated with the other regions, and thus formed a third entity. Finally, distinct regions belonging to the Language and Medial networks were found in the left angular gyrus, where these two systems could interface

Language lateralization in left-handed patients with schizophrenia.

International audienceWe evaluated hemispheric lateralization of language production in non-right-handed (NRH) patients with schizophrenia compared with matched right-handed (RH) patients, NRH control, and RH control subjects. First, the ability to generate verbs during overt training trials was checked in 78 subjects. They were then evaluated with functional magnetic resonance imaging (fMRI) while performing a covert verb generation task. No significant interactions between illness and handedness and no illness effect were observed in functional asymmetry. There was significantly less leftward asymmetry of the inferior frontal, precentral, and supramarginal gyri as well as the intra-parietal sulcus in non-right-handers compared to right-handers taking into account the task performances. Our findings suggested that decreased lateralization for language production was more closely related to handedness than to schizophrenia

Reproducibility of fMRI activations during a story listening task in patients with schizophrenia.

International audienceA prerequisite to longitudinal fMRI studies in schizophrenia is the knowledge on fMRI signal reliability in schizophrenia patients. We assessed the reproducibility of activations elicited by two fMRI sessions, which were 21 months apart, of a story listening paradigm in 10 schizophrenia patients and 10 healthy subjects. In both groups, we observed a high degree of spatial overlap of activation maps as well as a good reproducibility of signal variations assessed on a voxel-wise basis in temporal areas underlying early stages of language processing. Task performance, assessed through a comprehension questionnaire, had no impact on the activation reproducibility

Functional hemispheric lateralization for language in patients with schizophrenia

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Reduced functional cerebral lateralization: a biomarker of schizophrenia?

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Functional and white matter abnormalities in the language network in patients with schizophrenia: A combined study with diffusion tensor imaging and functional magnetic resonance imaging

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