Increased parahippocampal and lingual gyrification in first-episode schizophrenia

Objective: Cerebral gyrification is attributed to a large extent to genetic and intrauterine/ perinatal factors. Hence, investigating gyrification might offer important evidence for disturbed neurodevelopmental mechanisms in schizophrenia. As an extension of recent ROI analyses of gyrification in schizophrenia the present study is the first to compare on a node-by-node basis mean curvature as a sensitive parameter for the identification of local gyrification changes of the whole cortex in first-episode schizophrenia. Methods: A group of 54 patients with first-episode schizophrenia according to DSM-IV and 54 age and gender matched healthy control subjects were included. All participants underwent high-resolution T1-weighted MRI scans on a 1.5 T scanner. Mean curvature was calculated dividing the sum of the principal curvatures by two at each point of the curved surface as implemented in the Freesurfer Software package. Statistical cortical maps were created to estimate gyrification differences between groups based on a clustering approach. Results: A significantly increased gyrification was observed in first-episode schizophrenia patients relative to controls in a right parahippocampal-lingual cortex area. The cluster encompassed a surface area of 750 mm². A further analysis of cortical thickness of this cluster demonstrated concurrent significant reduced cortical thickness of this area. Conclusions: This is the first study to reveal an aberrant gyrification of the medial surface in first-episode schizophrenia. This finding is in line with substantial evidence showing medial temporal lobe abnormalities in schizophrenia. The present morphometric data provide further support for an early disruption of cortical maturation in schizophrenia

Enhanced rostral anterior cingulate cortex activation during cognitive control is related to orbitofrontal volume reduction in unipolar depression

Objective: In patients with major depressive disorder (MDD), enhanced activation of the rostral anterior cingulate cortex (rACC) during conflict resolution has been demonstrated with the use of functional magnetic resonance imaging (fMRI), which suggests dysregulation of the affective compartment of the ACC associated with error monitoring and cognitive control. Moreover, several previous studies have reported disrupted structural integrity in limbic brain areas and the orbitofrontal cortex in MDD. However, the relation between structural and functional alterations remains unclear. Therefore, the present study sought to investigate whether structural brain aberrations in terms of grey matter decreases directly in the medial frontal regions or in anatomically closely connected areas might be related to our previously reported functional alterations. Methods: A sample of 16 female, drug-free patients with an acute episode of MDD and 16 healthy control subjects matched for age, sex and education were examined with structural high-resolution T 1 -weighted MRI; fMRI images were obtained in the same session. Results: Voxel-based morphometry (VBM) revealed grey matter decreases in the orbitofrontal and subgenual cortex, in the hippocampus-amygdala complex and in the middle frontal gyrus. The relative hyperactivation of the rACC in terms of inability to deactivate this region during the Stroop Color-Word Test showed an inverse correlation with grey matter reduction in the orbitofrontal cortex. Conclusion: The present study provides strong evidence for an association between structural alterations in the orbitofrontal cortex and disturbed functional activation in the emotional compartment of the ACC in patients with MDD during cognitive control. Objectif : Chez des patients atteints de trouble dépressif majeur (TDM), on a démontré au moyen de l'imagerie par résonance magné-tique fonctionnelle (IRMf) une plus grande activité du cortex cingulaire antérieur rostral (CCAr) pendant la résolution des différends, ce qui indique une dysrégulation du compartiment affectif du CCA associé à la surveillance des erreurs et au contrôle de la cognition. De plus, plusieurs études antérieures ont signalé une perturbation de l'intégrité structurelle dans des aires limbiques du cerveau et le cortex orbitofrontal dans les cas de TDM. Le lien entre les altérations structurelles et fonctionnelles demeure toutefois flou. C'est pourquoi l'étude visait à déterminer si les aberrations structurelles du cerveau en termes de diminutions de la matière grise survenant directement dans les régions frontales médiales ou dans les régions reliées étroitement sur le plan anatomique pourraient être reliées aux altérations fonctionnelles signalées antérieurement. Méthodes : On a examiné par IRM structurelle haute résolution à pondération T 1 un échantillon composé de 16 femmes ne prenant pas de médicament et ayant un épisode aigu de TDM et de 16 sujets témoins en bonne santé jumelés en fonction de l'âge, du sexe et de l'éducation. On a obtenu des images IRMf au cours de la même séance. Résultats : La morphométrie Voxel a révélé des diminutions de la matière grise dans le cortex orbitofrontal et subgénual, dans le complexe hippocampeamygdales et dans la circonvolution frontale médiane. L'hyperactivation relative du CCAr (incapacité de désactiver cette région au cours du test de Stroop sur les couleurs et les mots) a révélé une corrélation inverse avec la réduction de la matière grise dans le cortex orbitofrontal. Conclusion : L'étude démontre solidement l'existence d'un lien entre des altérations structurelles du cortex orbitofrontal et la perturbation de l'activation fonctionnelle dans le compartiment émotionnel du CCA, au cours du contrôle cognitif chez les patients atteints de TDM

Frequency domains of resting state default mode network activity in schizophrenia

a b s t r a c t Probabilistic independent component analysis was applied to identify the default mode network (DMN) in resting state data obtained with functional magnetic resonance imaging from 25 DSM-IV schizophrenia and 25 matched healthy subjects. Power spectrum analysis showed a significant diagnosis  -frequency interaction and higher power in one frequency band, indicating an alteration of DMN frequency spectrum in schizophrenia

Association Between Learning Capabilities and Practice-Related Activation Changes in Schizophrenia

The present functional magnetic resonance imaging study investigated the neural correlates of practice-associated activation changes in patients with schizophrenia and their association with symptom severity. A group of patients (n = 24) were divided into more successful and less successful learners and were asked to perform a verbal overlearning task in the scanner. We found that both patient groups profited from practice, showing significant decreases in mean response times as well as significant learning-related decreases in cerebral activation. Direct comparison between groups yielded a relative hyperactivation in the group of the less successful learners at the beginning of practice, which showed a reduction with increasing practice. This was reflected by relatively stronger signal decreases in a predominantly fronto-parieto-cerebellar network. In the group of less successful learners, there was a negative correlation between general symptom scores and learning-related signal decreases in a task-relevant network involving cerebellar, inferior and middle frontal (BA 45/47, 46), superior parietal (BA 31), and superior temporal (BA 39) regions. Present data indicate that hyperactivity under high task demands might serve to identify those patients with less potential to profit from practice. However, at least in the context of moderate– to low–working memory demands, this activation abnormality seems to constitute a state rather than a trait characteristic, which patients manage to reduce by successful short-term learning. The findings also suggest that successful learners can better compensate potentially interfering effects exerted by disorder-related psychopathology

Association between schizophrenia and common variation in neurocan (NCAN), a genetic risk factor for bipolar disorder

A recent study found genome-wide significant association between common variation in the gene neurocan (NCAN, rs1064395) and bipolar disorder (BD). In view of accumulating evidence that BD and schizophrenia partly share genetic risk factors, we tested this single-nucleotide polymorphism for association with schizophrenia in three independent patient-control samples of European ancestry, totaling 5061 patients and 9655 controls. The rs1064395 A-allele, which confers risk for BD, was significantly over-represented in schizophrenia patients compared to controls (p=2.28×10(-3); odds ratio=1.11). Follow-up in non-overlapping samples from the Schizophrenia Psychiatric GWAS Consortium (5537 patients, 8043 controls) provided further support for our finding (p=0.0239, odds ratio=1.07). Our data suggest that genetic variation in NCAN is a common risk factor for BD and schizophreni