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ABSTRACT: The increased occurrence of obstetric complications (OCs) in patients with schizophrenia suggests that alterations in neurodevelopment may be of importance to the aetiology of the illness. Abnormal cortical folding may reflect subtle deviation from normal neurodevelopment during the foetal or neonatal period. In the present study, we hypothesized that OCs would be related to cortical folding abnormalities in schizophrenia patients corresponding to areas where patients with schizophrenia display altered cortical folding when compared with healthy controls.
In total, 54 schizophrenia patients and 54 healthy control subjects underwent clinical examination and magnetic resonance image scanning on a 1.5 T scanner. Information on OCs was collected from original birth records. An automated algorithm was used to calculate a three-dimensional local gyrification index (lGI) at numerous points across the cortical mantle.
In both schizophrenia patients and healthy controls, an increasing number of OCs was significantly related to lower lGI in the left pars triangularis (p<0.0005) in Broca's area. For five other anatomical cortical parcellations in the left hemisphere, a similar trend was demonstrated. No significant relationships between OCs and lGI were found in the right hemisphere and there were no significant case-control differences in lGI.
The reduced cortical folding in the left pars triangularis, associated with OCs in both patients and control subjects suggests that the cortical effect of OCs is caused by factors shared by schizophrenia patients and healthy controls rather than factors related to schizophrenia alone.
Psychological Medicine 10/2011; 42(6):1329-37. · 6.16 Impact Factor
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ABSTRACT: This article aims to validate the schizotypal personality questionnaire in a sample of French speaking adolescents. Because early schizotypal manifestations are predictive of psychosis-proneness, reliable self-report measures are crucial for early detection of vulnerability to schizophrenia during adolescence. Unlike most existing self-reports, the questionnaire de personnalité schizotypique (SPQ) assesses individual differences in all nine feature of DSM-IV schizotypal personality (i.e. ideas of reference, excessive social anxiety, odd beliefs, unusual perceptual experience, odd behaviour, no close friends, odd speech, constricted affect and suspiciousness). Furthermore, it yields dimensional scores concerning the main schizotypal factors, which represent valuable information for the clinician's case formulation and can be used as a screening instrument in the general population.
Our sample consisted of 174 adolescents (98 girls) between 12 and 17 years old. All completed the SPQ 74-item self-report. Participants were recruited in secondary schools in Switzerland, and through the child and adolescent community outpatient psychiatric service (office médico-pédagogique) affiliated to the University of Geneva's Psychiatry Department and to the Canton of Geneva Education Department. A confirmatory factorial analysis was conducted on our sample to test nine competing models of SPQ. The 3-factor model of Raine et al. was compared to concurrent 2, 3, and 4-factor models. Simple structure models of Raine et al. and Stefanis et al. were also tested.
The following observations were highlighted in our results: (1) goodness-of-fit indices are better for structures allowing cross loadings than for simple structures; (2) amongst the simple structures, the best goodness-of-fit index was obtained for the Raine model and (3) the fit between our data and the Raine model is improved by a cross loading for suspiciousness subscale. The latter seems problematic for the global data fitting. This led us to test simple structures models of Siever and Gunderson, Raine et al., and Stefanis et al., based on eight subscales rather than nine. Without suspiciousness subscale, goodness-of-fit indices are enhanced in these three models. The 3-factor model yields the clearest and most reliable results in comparison with other competing models. In summary, the best goodness-of-fit indices were obtained for the 3-factor Raine model. Goodness-of-fit indices could be improved by the exclusion of the suspiciousness scale.
Consistent with earlier analyses by Raine et al. and Dumas et al., our data confirm the 3-factor model of the SPQ (cognitive-perceptive; interpersonal; disorganized) in a sample of French speaking adolescents. Our analyses confirm that two dimensions are insufficient to explain the structure of schizotypy during adolescence. These results further suggest the stability of a 3-factor structure during lifespan. We note that the inclusion of the suspiciousness subscales engenders statistical issues. Most studies to date have dealt with these issues by performing a cross-loading with this subscale, or by the inclusion of a paranoid factor which is linked with the negative and the cognitive-perceptive factors. We found that the most statistically sound strategy was reached without the inclusion of the suspiciousness subscale. Future studies with larger samples could investigate the SPQ structure at an item-level, which carries the benefit of reduced restrictions on the factorial analysis. In conclusion, the current study shows that the French version SPQ constitutes a reliable self-report questionnaire for the assessment of schizotypal trait expression during adolescence that may assist in the evaluation of psychosis proneness in youths.
L Encéphale 09/2011; 37(4):299-307. · 0.63 Impact Factor
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ABSTRACT: Velocardiofacial syndrome (VCFS) is a neurogenetic disorder caused by a microdeletion on chromosome 22q11. Among other cognitive impairments and learning difficulties, affected individuals show difficulties in estimating time intervals (Debbané et al., 2005). Interestingly, neuroimaging studies have found an increased volume of the basal ganglia of people with VCFS (Eliez et al., 2002; Kates et al., 2004; Campbell et al., 2006). Given that the caudate nucleus represents a central component of the cerebral network underlying temporal perception skills, the present report proposes to examine potential relationships between cerebral alteration to the caudate nucleus and time estimation in individuals with VCFS.
A group of 30 patients with VCFS and 38 age-matched healthy individuals participated in time perception and time reproduction tasks. In the time perception task, individuals listened to two sequential stimuli and had to choose the longer of both stimuli by pressing a button. In the time reproduction task, subjects listened to a succession of sounds and once this succession had stopped they had to reproduce the same rhythm with their dominant index. Cerebral MRI images were also obtained for each participant. A manual tracing procedure was performed to measure the basal ganglia volume.
Participants with VCFS demonstrated significantly poorer performances during the time perception and time reproduction tasks in comparison to the control participants. Further, increased volume of the caudate nucleus was found in individuals with VCFS. Correlational analyses revealed a significant relationship between the caudate nucleus's volume and the performances obtained in the time perception task for control participants. This correlation was not found for individuals with VCFS.
The present results suggest that cerebral alterations to the caudate nucleus in VCFS may alter the temporal perception function it sustains.
L Encéphale 05/2011; 37 Suppl 1:S42-9. · 0.63 Impact Factor
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ABSTRACT: Source monitoring consists in identifying the origin of mental events. Recent research suggests that confusions over internally generated mental events may represent a cognitive marker for increased proneness to psychotic symptoms and disorders. We have examined source monitoring for actions in adolescents with the 22q11.2 deletion syndrome (22q11DS), a neurogenetic disease associated with high rates of schizophrenia during adulthood, and expected to observe source monitoring deficits in comparison to IQ-matched and typically developing controls.
Eighteen adolescents with 22q11DS, 17 adolescents matched for age and IQ, and also 17 adolescents matched for age participated in this study. Our adapted action monitoring paradigm asked subjects to visualize a series of actions in three different conditions: (1) visualize themselves performing the action; (2) visualize the experimenter performing the action; or (3) simply repeat the action statements without visualization of the action performer.
The adolescents with 22q11DS performed adequately in terms of recognition (hits), but in comparison to both control groups, they committed more source confusions on correctly recognized items. Further examination revealed that the adolescents were more likely to demonstrate confusions between exterior sources in which the self was not involved.
Source monitoring deficits can be observed in adolescents with 22q11DS, a syndrome putting them at high risk for developing schizophrenia. These deficits are discussed in terms of early cognitive processes associated with genetic risk for schizophrenia.
Psychological Medicine 07/2008; 38(6):811-20. · 6.16 Impact Factor
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ABSTRACT: Velo-cardio-facial syndrome (VCFS, 22q11.2 deletion) is characterized by severely delayed language development. The current study explored the integrity of verbal short-term memory (STM), a cognitive function critically involved in language development, in eight children with VCFS.
Using a multiple case study design, we presented a series of STM tasks exploring immediate serial recall for word and non-word lists to eight children with VCFS (aged 8-12 years) and to chronological-age-matched control groups. A first task assessed the integrity of phonological coding in verbal STM by comparing recall for phonologically similar and dissimilar words. Subsequently, the interaction between verbal knowledge and STM capacity was investigated by comparing recall for high- and low-imageability words, for high- and low-frequency words, and for words and non-words. A final task assessed short-term serial order recognition for digit sequences.
When computing the number of items recalled in the word recall tasks, independently of their serial position, only one child presented consistent difficulties. Short-term recall of non-words was normal in each child. Phonological similarity and verbal knowledge influenced STM performance to a similar extent in children with VCFS and controls. On the other hand, when applying a strict serial recall criterion, difficulties with the word and non-word recall tasks were observed in most children. Half of the patients were also impaired in the serial order recognition task.
Despite mild intellectual disability, it is possible for short-term retention capacities for verbal item information to be at an age-appropriate level in VCFS. However, STM for serial order information could be impaired more specifically.
Journal of Intellectual Disability Research 07/2006; 50(Pt 6):457-69. · 1.88 Impact Factor
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ABSTRACT: We present a segmentation method for fetal brain tissues of T2w MR images, based on the well known Expectation Maximization Markov Random Field (EM- MRF) scheme. Our main contribution is an intensity model composed of 7 Gaussian distribution designed to deal with the large intensity variability of fetal brain tissues. The second main contribution is a 3-steps MRF model that introduces both local spatial and anatomical priors given by a cortical distance map. Preliminary results on 4 subjects are presented and evaluated in comparison to manual segmentations showing that our methodology can successfully be applied to such data, dealing with large intensity variability within brain tissues and partial volume (PV).
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ABSTRACT: Development of technologies in the field of neuroimaging brought an increase interest in the quantification of cortical folding (gyrification), notably for neurogenetic and psychiatric disorders that may result from an early abnormal cortical development. For example, gyrification has been reported altered in schizophrenia (Kulynych, 1997; Harris, 2004), autism (Hardan, 2004), and Williams syndrome (Schmitt, 2002). Algorithms traditionally used to quantify gyrification measure the cortical perimeter on two-dimensional coronal sections of the brain, as first proposed by Zilles (Zilles, 1988). We propose here a new method inspired of the classical equation that takes into account the inherent 3-dimensional nature of the cortex. Brain MRI images were acquired for 30 typically developing individuals (6-30 years old) using a 1.5T scanner. Images were subsequently imported into the software Freesurfer (http://surfer.nmr.mgh.harvard.edu/), for removal of extra-cerebral structures, tissue segmentation and reconstruction of the cortical surface. Resulting cortical surfaces were analyzed using Matlab (http://www.mathworks.com/). For each brains lobe, 3D Gyrification Index (3D-GI) was defined as the ratio of the area of the total folded cortical surface over its convex hull. 3D-GI were then analyzed on two bases. First, we compared 3D-GI to those obtained with classical 2D algorithms for each subject. Then, we analyze the relationship between 3D-GI with variables that are known not to be correlated with GI, like age, weight, gender (Armstrong, 1995). We propose that the three-dimensional method will better detect small change in gyrification. Ultimately, such tools may improve our comprehension of cortical complexity in neurogenetic and psychiatric disorders.
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ABSTRACT: Normal course of cortical maturation has been evidenced for many years through gray matter volume measurements and abnormal gray matter volumes have frequently been reported as a part of a pathological brain development in neurogenetic or psychiatric disorders. The pathogenic processes underlying abnormal gray matter volume are not yet well understood, as either altered cortical thickness or a defect in cortical expansion may decrease cortical volume. Resolving this issue may provide clues for localizing the timing of the alteration. Indeed, expansion of the cortical surface is allowed by both increase in brain perimeter and folding of the cortical sheet (gyrification) during early brain development. Conversely, alteration of cortical thickness may occur at different developmental stage. Here, we aimed to identify the respective contribution of these processes to cortical volume in the parietal lobe, in a cohort of typically developing young individuals compared to patients affected by 22q11 Deletion Syndrome (22q11DS). 22q11DS is a common neurogenetic condition in which parietal gray matter (Eliez, 2000) and gyrification (Schaer, in press) are specifically altered early in development.
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ABSTRACT: In this work we present a method for the image analysis of Magnetic Resonance Imaging (MRI) of fetuses. Our goal is to segment the brain surface from multiple volumes (axial, coronal and sagittal acquisitions) of a fetus. To this end we propose a two-step approach: first, a Finite Gaussian Mixture Model (FGMM) will segment the image into 3 classes: brain, non-brain and mixture voxels. Second, a Markov Random Field scheme will be applied to re-distribute mixture voxels into either brain or non-brain tissue. Our main contributions are an adapted energy computation and an extended neighborhood from multiple volumes in the MRF step. Preliminary results on four fetuses of different gestational ages will be shown.
