Altered orbitofrontal sulcogyral pattern in schizophrenia

Attentional Control and Intelligence: MRI Orbital Frontal Gray Matter and Neuropsychological Correlates

Attentional control is a key function of working memory that is hypothesized to play an important role in psychometric intelligence. To test the neuropsychological underpinnings of this hypothesis, we examined full-scale IQ, as measured by the Wechsler Adult Intelligence Scale-Third Edition (WAIS-III), and attentional control, as measured by Trails B response time and Wisconsin Card Sorting (WCS) test perseverative errors in 78 healthy participants, 25 of whom also had available magnetic resonance imaging (MRI) gray matter volume studies of the orbital frontal cortex (OFC) parcellated into three regions: gyrus rectus, middle orbital gyrus, and lateral orbital gyrus. Hierarchical regression indicated that Trails B response time specifically explained 15.13% to 19.18% of the variation in IQ and WCS perseverative errors accounted for an additional 8.12% to 11.29% of the variance. Full-scale IQ correlated very strongly with right middle orbital gyrus gray matter volume (r = 0.610, p = 0.002), as did Trails B response time with left middle orbital gyrus gray matter volume (r = −0.608, p = 0.003). Trails B response time and right middle orbital gyrus gray matter volume jointly accounted for approximately 32.95% to 54.82% of the variance in IQ scores. These results provided evidence of the unique contributions of attentional control and OFC gray matter to intelligence.

Orbitofrontal sulcal and gyrus pattern in human: an anatomical study

The anatomical characterization of the orbitofrontal cortex in human is limited in literature instead of many functional and clinical studies involving it. Objective Anatomically define the orbitofrontal region aiming to possible neurosurgical treatments and unify the scientific nomenclature as well. Method We analyze eighty four human hemispheres using a surgical microscope. Then we chose four hemispheres and dissect them according to Klinger’ technique. Results We found five main sulcus: olfatory sulcus, orbital medial sulcus, orbital lateral sulcus, orbital transverse sulcus and orbital intermediate sulcus. These sulcus, excluding the intermediate sulcus, delimit five gyrus: rectus gurys, orbital medial gyrus, orbital anterior gyrus, orbital lateral gyrus and orbital posterior gyrus. The main sulcal configuration can be divided on four more frequently patterns. Conclusion Orbitofrontal cortex is associated with many psychiatric disorders. Better anatomical and functional characterization of the orbitofrontal cortex and its connections will improve our knowledge about these diseases.

Modeling a model: Mouse genetics, 22q11.2 Deletion Syndrome, and disorders of cortical circuit development

Understanding the developmental etiology of autistic spectrum disorders, attention deficit/hyperactivity disorder and schizophrenia remains a major challenge for establishing new diagnostic and therapeutic approaches to these common, difficult-to-treat diseases that compromise neural circuits in the cerebral cortex. One aspect of this challenge is the breadth and overlap of ASD, ADHD, and SCZ deficits; another is the complexity of mutations associated with each, and a third is the difficulty of analyzing disrupted development in at-risk or affected human fetuses. The identification of distinct genetic syndromes that include behavioral deficits similar to those in ASD, ADHC and SCZ provides a critical starting point for meeting this challenge. We summarize clinical and behavioral impairments in children and adults with one such genetic syndrome, the 22q11.2 Deletion Syndrome, routinely called 22q11DS, caused by micro-deletions of between 1.5 and 3.0 MB on human chromosome 22. Among many syndromic features, including cardiovascular and craniofacial anomalies, 22q11DS patients have a high incidence of brain structural, functional, and behavioral deficits that reflect cerebral cortical dysfunction and fall within the spectrum that defines ASD, ADHD, and SCZ. We show that developmental pathogenesis underlying this apparent genetic "model" syndrome in patients can be defined and analyzed mechanistically using genomically accurate mouse models of the deletion that causes 22q11DS. We conclude that "modeling a model", in this case 22q11DS as a model for idiopathic ASD, ADHD and SCZ, as well as other behavioral disorders like anxiety frequently seen in 22q11DS patients, in genetically engineered mice provides a foundation for understanding the causes and improving diagnosis and therapy for these disorders of cortical circuit development.

The Disrupted-in-Schizophrenia-1 Ser704Cys polymorphism and brain neurodevelopmental markers in schizophrenia and healthy subjects

Increasing evidence has implicated the role of Disrupted-in-Schizophrenia-1 (DISC1), a potential susceptibility gene for schizophrenia, in early neurodevelopmental processes. However, the effect of its genotype variation on brain morphologic changes related to neurodevelopmental abnormalities in schizophrenia remains largely unknown. This magnetic resonance imaging study examined the association between DISC1 Ser704Cys polymorphism and a range of brain neurodevelopmental markers [cavum septi pellucidi (CSP), adhesio interthalamica (AI), olfactory sulcus depth, and sulcogyral pattern (Types I, II, III, and IV) in the orbitofrontal cortex (OFC)] in an all Japanese sample of 75 schizophrenia patients and 87 healthy controls. The Cys carriers had significantly larger CSP than the Ser homozygotes for both schizophrenia patients and healthy controls. The Cys carriers also exhibited a reduction in the Type I pattern of the right OFC in the healthy controls, but not in the schizophrenia patients. The DISC1 Ser704Cys polymorphism did not affect the AI and olfactory sulcus depth in either group. These results suggested a possible role of the DISC1 genotype in the early neurodevelopment of human brains, but failed to show its specific role in the neurodevelopmental pathology of schizophrenia.

Orbitofrontal cortex volume and intrinsic religiosity in non-clinical psychosis

Research indicates that religiosity plays a complex role in mental illness. Despite this link, little work has been done to clarify the role of religiosity in persons exhibiting non-clinical psychosis (NCP, individuals experiencing fleeting psychotic-like symptoms in the absence of a formal psychotic disorder). Further, there are no NCP investigations into whether abnormalities exist in brain structures that are associated with religiosity. Understanding these relationships in NCP is important to clarify the role of religiosity and brain structural anomalies in psychosis. Twenty individuals experiencing NCP and twenty controls were assessed for intrinsic religiosity (IR; motivation/commitment to religious beliefs and/or practices) using a well-validated self-report scale. Structural magnetic resonance imaging was used to determine volumes of the orbitofrontal cortex (OFC), a critical region that has been associated with increased religiosity. Results indicate that IR is elevated in the NCP group, and that these individuals exhibit bilateral volume reduction in both the lateral and medial OFC. Sample-wide correlations are non-significant, but show notable relationships between smaller OFC regions and increased IR. Significant negative relationships were found between OFC volume and depressive and negative symptoms. Overall, results suggest that brain abnormalities associated with NCP may also confer a heightened susceptibility for religiosity.

The polymorphism of YWHAE, a gene encoding 14-3-3epsilon, and orbitofrontal sulcogyral pattern in patients with schizophrenia and healthy subjects

An altered sulcogyral pattern in the orbitofrontal cortex (OFC) has been implicated in schizophrenia as a possible marker of abnormal neurodevelopment, while its genetic mechanism remains unknown. This magnetic resonance imaging study investigated the relationship between the polymorphism of YWHAE (rs28365859), a gene encoding 14-3-3epsilon that is a Disrupted-in-Schizophrenia 1 (DISC1)-interacting molecule associated with neuronal development, and the OFC subtypes of the 'H-shaped' sulcus (Types I, II, and III) in a Japanese sample of 72 schizophrenia patients and 86 healthy controls. The schizophrenia patients had significantly increased Type III (p = 0.004) and decreased Type I (p = 0.013) expression on the right hemisphere compared to the controls. The subjects carrying the protective C allele showed a decrease in Type III (p = 0.005) and an increase in Type I (p = 0.017) compared to the G allele homozygotes, especially for the healthy subjects in the left hemisphere. These results suggest a possible role for the YWHAE genotype in the early development of the OFC sulcogyral pattern, but its effect alone is not likely to explain the altered sulcogyral pattern in schizophrenia.

Altered orbitofrontal sulcogyral patterns in adult males with high-functioning autism spectrum disorders

Functions of the orbitofrontal cortex include diverse social, cognitive and affective processes, many of which are abnormal in autism spectrum disorders (ASDs). Recently, altered orbitofrontal sulcogyral patterns have been revealed in several psychiatric conditions, such as schizophrenia, indicating a possibility that altered orbitofrontal sulcogyral morphology reflects abnormal neurodevelopment. However, the presence of sulcal alterations in ASD remains unexplored. Using structural magnetic resonance imaging, subtypes of the 'H-shaped' sulcus (Type I, II and III, in order of frequency), posterior orbital sulcus (POS) and intermediate orbital sulcus were identified in each hemisphere of adult males with ASD (n = 51) and matched normal controls (n = 55) based on the study by Chiavaras and Petrides. ASD showed a significantly altered distribution of H-shaped sulcal subtypes in both hemispheres, with a significant increase of Type III. A significant alteration in the distribution of sulcal subtypes was also identified in the right hemisphere POS of ASD. Categorical regression analysis revealed that Type I and II expressions predicted a reduced total Autism-Spectrum Quotient score. Furthermore, Type I expression was associated with a reduced 'attention to detail' subscale score. The results demonstrate that altered sulcogyral morphology can be a marker for abnormal neurodevelopment leading to the increased risk of developing autism.

Sulcogyral pattern and sulcal count of the orbitofrontal cortex in individuals at ultra high risk for psychosis

Three types of orbitofrontal cortex (OFC) sulcogyral patterns have been identified in the general population. The distribution of these three types has been found to be altered in individuals at genetic risk of psychosis, and in patients with first episode psychosis (FEP) and chronic schizophrenia. This study aims at establishing whether altered OFC sulcogyral patterns were present in a large cohort of individuals at ultra high risk (UHR) for psychosis. OFC pattern type was classified and the number of posterior and intermediate sulci present on the surface of the OFC was counted. OFC sulcogyral type and the number of sulci were compared between controls (n=58) and UHR participants who transitioned (n=49) versus those who did not transition (n=77) to psychosis. Finally, the relationship between sulcogyral type and number of sulci with intellectual quotient (IQ), symptom severity and social functioning of UHR individuals was explored. In line with other studies conducted in chronic schizophrenia and FEP, UHR individuals who later transitioned to psychosis showed a reduced incidence of the Type I OFC on the right hemisphere compared to controls (χ(2)=19.847, p<0.001). These highly consistent results point towards the protective effect of possessing a Type I OFC in the right hemisphere. Furthermore, OFC sulcus counts revealed that controls presented with a higher number of posterior (right hemisphere; χ(2)=11.658, p=0.003) and intermediate sulci (left: χ(2)=6.643, p=0.036; right: χ(2)=11.726, p=0.020) when compared to UHR individuals. However, no associations between OFC types or sulcus count and IQ, symptoms and functioning were observed.

The effect of odor valence on olfactory performance in schizophrenia patients, unaffected relatives and at-risk youth

Given the presence of odor identification impairment in individuals with schizophrenia and recent evidence of aberrant odor hedonic processing, the aim of this investigation was to examine the influence of valence and intensity on odor identification in schizophrenia patients, their first-degree family members, and young persons at clinical risk for psychosis. Participants completed the 16-item Sniffin' Stick Odor Identification Test. A logistic regression was conducted to assess the influence of valence and intensity on odor identification accuracy. Identification performance in the schizophrenia patients and youths at clinical risk for psychosis was significantly influenced by odor valence, but not intensity. Identification accuracy in first-degree family members was not influenced by valence or intensity. These data suggest that abnormalities in odor valence perception may represent an environmentally-mediated marker for hedonic disturbance that could have predictive utility in future conversion to psychosis. Further research examining the utility of odor valence measures as markers for psychosis risk is warranted.

Sulcogyral patterns and morphological abnormalities of the orbitofrontal cortex in psychosis

Three types of OFC sulcogyral patterns have been identified in the general population. The distribution of these three types has been found altered in individuals at genetic risk of psychosis, first episode psychosis (FEP) and chronic schizophrenia. The aim of this study was to replicate and extend previous research by additionally investigating: intermediate and posterior orbital sulci, cortical thickness, and degree of gyrification/folding of the OFC, in a large sample of FEP patients and healthy controls. OFC pattern type was classified based on a method previously devised, using T1-weighted magnetic resonance images. Cortical thickness and local gyrification indices were calculated using FreeSurfer. Occurrence of Type I pattern was decreased and Type II pattern was increased in FEP patients for the right hemisphere. Interestingly, controls displayed an OFC pattern type distribution that was disparate to that previously reported. Significantly fewer intermediate orbital sulci were observed in the left hemisphere of patients. Grey matter thickness of orbitofrontal sulci was reduced bilaterally, and left hemisphere reductions were related to OFC pattern type in patients. There was no relationship between pattern type and degree of OFC gyrification. An interaction was found between the number of intermediate orbital sulci and OFC gyrification; however this group difference was specific to only the small subsample of people with three intermediate orbital sulci. Given that cortical folding is largely determined by birth, our findings suggest that Type II pattern may be a neurodevelopmental risk marker while Type I pattern may be somewhat protective. This finding, along with compromised orbitofrontal sulci thickness, may reflect early abnormalities in cortical development and point toward a possible endophenotypic risk marker of schizophrenia-spectrum disorders.

Altered depth of the olfactory sulcus in first-episode schizophrenia

A shallow olfactory sulcus has been reported in chronic schizophrenia, possibly reflecting abnormal forebrain development during early gestation. However, it remains unclear whether this abnormality exists at the early illness stage and/or develops progressively over the course of the illness. This magnetic resonance imaging (MRI) study investigated the length and depth of the olfactory sulcus in 64 first-episode schizophrenia patients and 64 controls, of whom longitudinal MRI data (mean inter-scan interval=2.6 years) were available for 20 patients and 21 controls. In the cross-sectional comparison at the baseline, the schizophrenia patients had a significantly shallower olfactory sulcus compared with the controls bilaterally, but there was no group difference in its anterior-posterior length. A longitudinal comparison demonstrated that the sulcus length and depth did not change over time in either group. The olfactory sulcus measures of the patients did not significantly correlate with clinical variables such as onset age, medication or symptom severity. These findings suggest that the olfactory sulcus depth, but not length, may be a static vulnerability marker of schizophrenia that reflects early neurodevelopmental abnormality.

Orbitofrontal sulcogyral patterns are related to temperamental risk for psychopathology

There are marked individual differences in the pattern of cortical (sulcogyral) folding in the orbitofrontal cortex (OFC), and there is a growing literature suggesting that these individual differences are associated with risk for psychotic disorders. To date, however, no study has investigated whether OFC folding patterns are associated with broader risk factors relevant to a range of psychopathology. This study helps address this knowledge gap by examining whether OFC sulcogyral folding patterns are associated with putative risk factors, specifically affective temperament and psychiatric symptoms, in a large community sample (N = 152) of adolescents. Results showed that the most common pattern of folding ('Type I', marked by discontinuity of the medial orbital sulcus and continuity of the lateral orbital sulcus) was associated with low levels of Surgency, high levels of Negative Affectivity (in girls) and higher depressive symptoms. This pattern was also associated with reduced thickness of OFC gray matter. Overall, the findings, combined with previous work, suggest some specificity of neurodevelopmental risk for different types of psychopathology. Thus, these results have the potential to inform the early identification of at-risk individuals.

Higher gamma-aminobutyric acid neuron density in the white matter of orbital frontal cortex in schizophrenia

BACKGROUND

In the orbitofrontal cortex (OFC), reduced gray matter volume and reduced glutamic acid decarboxylase 67kDa isoform (GAD67) messenger (m)RNA are found in schizophrenia; however, how these alterations relate to developmental pathology of interneurons is unclear. The present study therefore aimed to determine if increased interstitial white matter neuron (IWMN) density exists in the OFC; whether gamma-aminobutyric acid (GABA)ergic neuron density in OFC white matter was altered; and how IWMN density may be related to an early-expressed inhibitory neuron marker, Dlx1, in OFC gray matter in schizophrenia.

METHODS

IWMN densities were determined (38 schizophrenia and 38 control subjects) for neuronal nuclear antigen (NeuN+) and 65/67 kDa isoform of glutamic acid decarboxylase immunopositive (GAD65/67+) neurons. In situ hybridization was performed to determine Dlx1 and GAD67 mRNA expression in the OFC gray matter.

RESULTS

NeuN and GAD65/67 immunopositive cell density was significantly increased in the superficial white matter in schizophrenia. Gray matter Dlx1 and GAD67 mRNA expression were reduced in schizophrenia. Dlx1 mRNA levels were negatively correlated with GAD65/67 IWMN density.

CONCLUSIONS

Our study provides evidence that pathology of IWMNs in schizophrenia includes GABAergic interneurons and that increased IWMN density may be related to GABAergic deficits in the overlying gray matter. These findings provide evidence at the cellular level that the OFC is a site of pathology in schizophrenia and support the hypothesis that inappropriate migration of cortical inhibitory interneurons occurs in schizophrenia.

Anterior temporobasal sulcal morphology: development of a reliable rating protocol and normative data

The three anterior temporobasal (aTB) sulci, which are the collateral, rhinal, and occipitotemporal sulci, contribute to the morphology of memory-related structures and are important landmarks for neuroimaging. Prevalence of inter-connections among these sulci may distinguish healthy adults and individuals with memory-related disorders (Kim et al. Neurology 70:2159-2165, 2008; Zhan et al. Hum Brain Mapp 30:874-882, 2009). However, methods for quantifying the existence and nature of such connections are vague and varied, and normative frequencies are inconsistent across studies. Therefore, the goals of the current study are twofold: (1) to develop a reliable method of identifying aTB sulci and their interconnections based on surface renderings generated from serial magnetic resonance images (MRIs). This protocol includes training materials and a rating log (see supplementary materials) that can be disseminated and applied by other researchers. (2) To determine the prevalence of interconnections among the three aTB sulci in a large sample of healthy adults (200 undergraduate students), which can be used as normative data for future comparison with clinical samples. Notably, the resulting protocol, called the Sulcal Classification Rating Protocol for anterior Temporobasal sulci, distinguishes "clear" from "ambiguous" connections. When only clear connections are included, our prevalence rates are consistent with post-mortem findings of Ono et al. (Atlas of the Cerebral Sulci. Thieme Medical Publishers, Inc., New York, 1990); when both clear and ambiguous connections are counted as a connection, our results largely replicate MRI-based findings (e.g., Kim et al. Neurology 70:2159-2165, 2008). We propose that systematic variations in rater classification of ambiguous connections could explain discrepancies in the literature.

In search of the functional neuroanatomy of sociality: MRI subdivisions of orbital frontal cortex and social cognition

We examined social cognition in a sample of healthy participants who had prior magnetic resonance imaging (MRI) gray matter volume studies of the orbital frontal cortex (OFC) that was parcellated into three regions: gyrus rectus, middle orbital gyrus and lateral orbital gyrus. These subjects also completed a self-report measure of Machiavelli personality traits, along with psychometric tests of social comprehension and declarative episodic memory, all of which we used as proxy measures to examine various features of social cognition. The data pointed to distinct functional-anatomical relationships highlighted by strong correlations of left lateral orbital gyrus and Machiavellian scores and right middle orbital gyrus with social comprehension and declarative episodic memory. In addition, hierarchical regression analyses revealed statistical evidence of a double dissociation between Machiavellian scores and left lateral orbital gyrus on one hand, and social comprehension with right middle orbital gyrus, on the other hand. To our knowledge, these findings are the first to show evidence linking normal variation in OFC subregions and different aspects of social cognition.

Sexually dimorphic distribution of orbitofrontal sulcogyral pattern in schizophrenia

AIM

The sulcogyral pattern of the orbitofrontal cortex (OFC) is characterized by a remarkable inter-individual variability that likely reflects neurobehavioral traits and genetic aspects of neurodevelopment. The aim of the present study was to evaluate the OFC sulcogyral pattern of patients with schizophrenia (SZ) and healthy controls (HC) to determine group differences in OFC sulcogyral pattern as well as gender differences between groups.

METHODS

Forty-seven SZ patients (M/F, 23/24) and forty-seven HC (M/F, 17/30), matched on age and gender, were analyzed using magnetic resonance imaging. The sulcogyral pattern was classified into type I, II, or III based on the guidelines set by Chiavaras and Petrides in a previous paper. Chi-squared analysis was used to investigate group and gender differences in the sulcogyral pattern distribution, and categorical regression was used to explore clinical correlations.

RESULTS

The distribution of OFC sulcogyral pattern in HC replicated the results found in the previous study (left, χ(2) = 0.02, P = 0.989; right, χ(2) = 0.97, P = 0.616), in that there were no gender differences. Moreover, the distribution in SZ-M was in accordance with that in the previous study (left, χ(2) = 1.59, P = 0.451; right, χ(2) = 0.14, P = 0.933). Additionally, within SZ-M, patients with the type III pattern had a higher total positive and negative syndrome scale score (β = 0.902, F = 14.75, P = 0.001). In contrast, the distribution in the right hemisphere in the SZ-F group differed significantly from that observed in SZ-M (χ(2) = 6.017, P = 0.046), but did not differ from HC (χ(2) = 2.557, P = 0.110).

CONCLUSION

OFC sulcogyral pattern is altered in SZ-M but not in SZ-F, possibly reflecting gender differences in early neurodevelopment.

In-vivo measurement of cortical morphology: means and meanings

PURPOSE OF REVIEW

Study of the variability of the cortical mantle thickness is now a key issue in neuroimaging. Here we describe a more recent trend aiming at the study of the variability of the cortical folding morphology.

RECENT FINDINGS

Computerized three-dimensional versions of gyrification index and other morphometric features dedicated to the folding patterns are modified in psychiatric syndromes and neurologic disorders. These observations provide new insights into the mechanisms involved in abnormal development or abnormal aging.

SUMMARY

Quantification of the folding morphology will contribute to the global endeavor aiming at building biomarkers from neuroimaging data, with a specific focus on developmental diseases.

"Where do auditory hallucinations come from?"--a brain morphometry study of schizophrenia patients with inner or outer space hallucinations

Auditory verbal hallucinations are a cardinal symptom of schizophrenia. Bleuler and Kraepelin distinguished 2 main classes of hallucinations: hallucinations heard outside the head (outer space, or external, hallucinations) and hallucinations heard inside the head (inner space, or internal, hallucinations). This distinction has been confirmed by recent phenomenological studies that identified 3 independent dimensions in auditory hallucinations: language complexity, self-other misattribution, and spatial location. Brain imaging studies in schizophrenia patients with auditory hallucinations have already investigated language complexity and self-other misattribution, but the neural substrate of hallucination spatial location remains unknown. Magnetic resonance images of 45 right-handed patients with schizophrenia and persistent auditory hallucinations and 20 healthy right-handed subjects were acquired. Two homogeneous subgroups of patients were defined based on the hallucination spatial location: patients with only outer space hallucinations (N=12) and patients with only inner space hallucinations (N=15). Between-group differences were then assessed using 2 complementary brain morphometry approaches: voxel-based morphometry and sulcus-based morphometry. Convergent anatomical differences were detected between the patient subgroups in the right temporoparietal junction (rTPJ). In comparison to healthy subjects, opposite deviations in white matter volumes and sulcus displacements were found in patients with inner space hallucination and patients with outer space hallucination. The current results indicate that spatial location of auditory hallucinations is associated with the rTPJ anatomy, a key region of the "where" auditory pathway. The detected tilt in the sulcal junction suggests deviations during early brain maturation, when the superior temporal sulcus and its anterior terminal branch appear and merge.

Axons pull on the brain, but tension does not drive cortical folding

During human brain development, the cerebral cortex undergoes substantial folding, leading to its characteristic highly convoluted form. Folding is necessary to accommodate the expansion of the cerebral cortex; abnormal cortical folding is linked to various neurological disorders, including schizophrenia, epilepsy, autism, and mental retardation. Although this process requires mechanical forces, the specific force-generating mechanisms that drive folding remain unclear. The two most widely accepted hypotheses are as follows: (1) Folding is caused by differential growth of the cortex and (2) folding is caused by mechanical tension generated in axons. Direct evidence supporting either theory, however, is lacking. Here we show that axons are indeed under considerable tension in the developing ferret brain, but the patterns of tissue stress are not consistent with a causal role for axonal tension. In particular, microdissection assays reveal that significant tension exists along axons aligned circumferentially in subcortical white matter tracts, as well as those aligned radially inside developing gyri (outward folds). Contrary to previous speculation, however, axonal tension is not directed across developing gyri, suggesting that axon tension does not drive folding. On the other hand, using computational (finite element) models, we show that differential cortical growth accompanied by remodeling of the subplate leads to outward folds and stress fields that are consistent with our microdissection experiments, supporting a mechanism involving differential growth. Local perturbations, such as temporal differences in the initiation of cortical growth, can ensure consistent folding patterns. This study shows that a combination of experimental and computational mechanics can be used to evaluate competing hypotheses of morphogenesis, and illuminate the biomechanics of cortical folding.

Volume reduction and altered sulco-gyral pattern of the orbitofrontal cortex in first-episode schizophrenia

BACKGROUND

Although clinical and neuropsychological findings have implicated functional deficits of the orbitofrontal cortex (OFC) in schizophrenia, structural magnetic resonance imaging (MRI) studies of this region have yielded inconsistent findings. In addition, it remains elusive whether the OFC morphology in first-episode patients is related to their clinical features.

METHOD

MR images were acquired from 42 (24 males, 18 females) first-episode schizophrenia patients and 35 (20 males, 15 females) age-, gender-, and parental socio-economic status (SES)-matched healthy subjects. The OFC sub-regions (orbital gyrus and straight gyrus) were measured on contiguous 1-mm-thick coronal slices. The OFC sulco-gyral pattern was also evaluated for each subject. Furthermore, the relationships between OFC morphology and clinical measures were examined.

RESULTS

The volumes of the bilateral orbital gyri were significantly reduced in schizophrenia patients compared with healthy subjects, whereas the volumes of the straight gyri did not show differences between the groups. Among the schizophrenia patients, the volume of the left orbital gyrus was inversely correlated with their SES and illness duration. The OFC sulco-gyral patterns were significantly different between the patients and controls in the right hemisphere.

CONCLUSION

This study demonstrated morphologic abnormalities of the OFC in first-episode schizophrenia patients, which may have reflected neurodevelopmental aberrations and neurodegenerative changes during the first episode of the illness. Our findings also suggest that such brain structural changes are related to the social dysfunction observed in schizophrenia.

Posterior orbitofrontal sulcogyral pattern associated with orbitofrontal cortex volume reduction and anxiety trait in panic disorder

AIMS

The posterior region of the orbitofrontal cortex (OFC), which forms its sulcogyral pattern during neurodevelopment, receives multisensory inputs. The purpose of the present study was to assess the relationship between posterior OFC sulcogyral pattern and OFC volume difference in patients with panic disorder.

METHODS

The anatomical pattern of the posterior orbital sulcus (POS) was classified into three subtypes (absent POS, single POS, double POS) using 3-D high-spatial resolution magnetic resonance images obtained from 28 patients with panic disorder and 28 age- and gender-matched healthy controls. Optimized voxel-based morphometry (VBM) was performed to assess OFC volume differences between the two groups by subtype. Categorical regression analysis was applied to examine the association of POS subtypes with State-Trait Anxiety Inventory and Revised Neuroticism-Extraversion-Openness Personality Inventory scores.

RESULTS

No significant difference was found in POS subtype distribution between control subjects and patients with panic disorder. VBM, however, indicated volume reduction in the right posterior-medial OFC region in panic disorder patients with absent POS and single POS. Single POS was positively associated with Trait-Anxiety (beta = 0.446, F = 6.409, P = 0.020), and absent POS was negatively associated with Trait-Anxiety (beta = -0.394, F = 5.341, P = 0.032) and Neuroticism trait (beta = -0.492, F = 6.989, P = 0.017).

CONCLUSIONS

POS subtypes may be relevant to volume reduction in OFC and the anxiety trait in patients with panic disorder. These findings suggest that volume reduction in OFC in panic disorder may be associated with neurodevelopment.

LPA receptors: subtypes and biological actions

Lysophosphatidic acid (LPA) is a small, ubiquitous phospholipid that acts as an extracellular signaling molecule by binding to and activating at least five known G protein-coupled receptors (GPCRs): LPA(1)-LPA(5). They are encoded by distinct genes named LPAR1-LPAR5 in humans and Lpar1-Lpar5 in mice. The biological roles of LPA are diverse and include developmental, physiological, and pathophysiological effects. This diversity is mediated by broad and overlapping expression patterns and multiple downstream signaling pathways activated by cognate LPA receptors. Studies using cloned receptors and genetic knockout mice have been instrumental in uncovering the significance of this signaling system, notably involving basic cellular processes as well as multiple organ systems such as the nervous system. This has further provided valuable proof-of-concept data to support LPA receptors and LPA metabolic enzymes as targets for the treatment of medically important diseases that include neuropsychiatric disorders, neuropathic pain, infertility, cardiovascular disease, inflammation, fibrosis, and cancer.

Searching for the Anatomy of Dissociative Amnesia

Brain damage was traditionally seen as the product of a neurological disease or injury. Nevertheless, modern brain imaging techniques have provided increasing evidence for alterations in brain tissue and metabolism for a number of psychiatric disorders. Though for a while “dissociated” ( Spiegel, 2006 ) from the clinical and scientific arena, dissociative disorders have in the last several years received a renewed interest among several groups of researchers, who embarked on the work of disentangling their neural correlates. We review data from our own research as well as others, which point to distinct changes in brain regions underlying dissociative amnes(t)ic disorders. These changes may consist of overall reductions in brain metabolism or more selective alterations primarily in the right temporo-frontal cortices. Recent evidence with refined magnetic resonance imaging techniques furthermore reveals selective fiber degenerations in these regions. While these changes may persist and probably even intensify in some patients, they may be reversible in others – especially if treatment is carried out successfully within short time after onset. Implications of these findings for the pathogenetic conceptualization of dissociative amnes(t)ic disorders are outlined.

Brain surface contraction mapped in first-episode schizophrenia: a longitudinal magnetic resonance imaging study

Schizophrenia is associated with structural brain abnormalities, but the timing of onset and course of these changes remains unclear. Longitudinal magnetic resonance imaging (MRI) studies have demonstrated progressive brain volume decreases in patients around and after the onset of illness, although considerable discrepancies exist regarding which brain regions are affected. The anatomical pattern of these progressive changes in schizophrenia is largely unknown. In this study, MRI scans were acquired repeatedly from 16 schizophrenia patients approximately 2 years apart following their first episode of illness, and also from 14 age-matched healthy subjects. Cortical Pattern Matching, in combination with Structural Image Evaluation, using Normalisation, of Atrophy, was applied to compare the rates of cortical surface contraction between patients and controls. Surface contraction in the dorsal surfaces of the frontal lobe was significantly greater in patients with first-episode schizophrenia (FESZ) compared with healthy controls. Overall, brain surface contraction in patients and healthy controls showed similar anatomical patterns, with that of the former group exaggerated in magnitude across the entire brain surface. That the pattern of structural change in the early course of schizophrenia corresponds so closely to that associated with normal development is consistent with the hypothesis that a schizophrenia-related factor interacts with normal adolescent brain developmental processes in the pathophysiology of schizophrenia. The exaggerated progressive changes seen in patients with schizophrenia may reflect an increased rate of synaptic pruning, resulting in excessive loss of neuronal connectivity, as predicted by the late neurodevelopmental hypothesis of the illness.

Positional and surface area asymmetry of the human cerebral cortex

Previous studies of cortical asymmetry have relied mainly on voxel-based morphometry (VBM), or manual segmentation of regions of interest. This study uses fully automated, surface-based techniques to analyse position and surface area asymmetry for the mid-surfaces of 112 right-handed subjects' cortical hemispheres from a cohort of young adults. Native space measurements of local surface area asymmetry and vertex position asymmetry were calculated from surfaces registered to a previously validated hemisphere-unbiased surface-based template. Our analysis confirms previously identified hemispheric asymmetries (Yakovlevian torque, frontal and occipital petalia) in enhanced detail. It does not support previous findings of gender/asymmetry interactions or rightward planum parietale areal increase. It reveals several new findings, including a striking leftward increase in surface area of the supramarginal gyrus (peak effect 18%), compared with a smaller areal increase in the left Heschl's gyrus and planum temporale region (peak effect 8%). A second finding was rightward increase in surface area (peak effect 10%) in a band around the medial junction between the occipital lobe, and parietal and temporal lobes. By clearly separating out the effects of structural translocation and surface area change from those of thickness and curvature, this study resolves the confound of these variables inherent in VBM studies.

Meta-analysis of the effects of repetitive transcranial magnetic stimulation (rTMS) on negative and positive symptoms in schizophrenia

BACKGROUND

A growing body of evidence suggests that repetitive transcranial magnetic stimulation (rTMS) can alleviate negative and positive symptoms of refractory schizophrenia. However, trials to date have been small and results are mixed.

METHODS

We performed meta-analyses of all prospective studies of the therapeutic application of rTMS in refractory schizophrenia assessing the effects of high-frequency rTMS to the left dorsolateral prefrontal cortex (DLPFC) to treat negative symptoms, and low-frequency rTMS to the left temporo-parietal cortex (TPC) to treat auditory hallucinations (AH) and overall positive symptoms.

RESULTS

When analyzing controlled (active arms) and uncontrolled studies together, the effect sizes showed significant and moderate effects of rTMS on negative and positive symptoms (based on PANSS-N or SANS, and PANSS-P or SAPS, respectively). However, the analysis for the sham-controlled studies revealed a small non-significant effect size for negative (0.27, p=0.417) and for positive symptoms (0.17, p=0.129). When specifically analyzing AH (based on AHRS, HCS or SAH), the effect size for the sham-controlled studies was large and significant (1.04; p=0.002).

CONCLUSIONS

These meta-analyses support the need for further controlled, larger trials to assess the clinical efficacy of rTMS on negative and positive symptoms of schizophrenia, while suggesting the need for exploration for alternative stimulation protocols.

Developmental disruptions in neural connectivity in the pathophysiology of schizophrenia

Schizophrenia has been thought of as a disorder of reduced functional and structural connectivity. Recent advances in neuroimaging techniques such as functional magnetic resonance imaging, structural magnetic resonance imaging, diffusion tensor imaging, and small animal imaging have advanced our ability to investigate this hypothesis. Moreover, the power of longitudinal designs possible with these noninvasive techniques enable the study of not just how connectivity is disrupted in schizophrenia, but when this disruption emerges during development. This article reviews genetic and neurodevelopmental influences on structural and functional connectivity in human populations with or at risk for schizophrenia and in animal models of the disorder. We conclude that the weight of evidence across these diverse lines of inquiry points to a developmental disruption of neural connectivity in schizophrenia and that this disrupted connectivity likely involves susceptibility genes that affect processes involved in establishing intra- and interregional connectivity.

Summary of the 1st Schizophrenia International Research Society Conference oral sessions, Venice, Italy, June 21-25, 2008: the rapporteur reports

The Schizophrenia International Research Society held its first scientific conference in Venice, Italy, June 21 to 25th, 2008. A wide range of controversial topics were presented in overlapping and plenary oral sessions. These included new genetic studies, controversies about early detection of schizophrenia and the prodrome, treatment issues, clinical characteristics, cognition, neuropathology and neurophysiology, other etiological considerations, substance abuse co-morbidity, and animal models for investigating disease etiology and for use as targets in drug studies. Young investigators in the field were awarded travel grants to participate in the congress and one of their roles was to summarize the oral sessions and subsequent discussions. The reports that follow are the culmination of this work produced by 30 young investigators who attended the congress. It is hoped that these summaries will be useful synopses of what actually occurred at the congress for those who did not attend each session or were unable to be present. The abstracts of all presentations, as submitted by the authors a few months prior, were previously published as supplement 2 to volume 102/1-3, June 2008.

Remission status and cortical thickness in childhood-onset schizophrenia

OBJECTIVE

Few studies have examined prediction of schizophrenia outcome in relation to brain magnetic resonance imaging measures. In this study, remission status at the time of discharge was examined in relation to admission cortical thickness for childhood-onset schizophrenia probands. We hypothesized that total, frontal, temporal, and parietal gray matter thickness would be greater in patients who subsequently remit.

METHOD

The relation between admission cortical brain thickness on magnetic resonance imaging and remission status at the time of discharge an average of 3 months later was examined for 56 individuals (32 males) ages 6 to 19 diagnosed with childhood-onset schizophrenia. Cortical thickness was measured across the cerebral hemispheres at admission. Discharge remission criteria were adapted from the 2005 Remission in Schizophrenia Working Group criteria.

RESULTS

Patients remitted at discharge (n = 16 [29%]) had thicker regional cortex in left orbitofrontal, left superior, and middle temporal gyri and bilateral postcentral and angular gyri (p < or = .008).

CONCLUSIONS

Our results provide neuroanatomic correlates of clinical remission in schizophrenia and evidence that response to treatment may be mediated by these cortical brain regions.

Quantification of thalamocortical tracts in schizophrenia on probabilistic maps

Diffusion properties of the thalamocortical pathways were compared between 30 schizophrenic patients and 22 healthy age-matched and sex-matched volunteers. T1-weighted and diffusion tensor images were used for cortical parcellation and probabilistic tractography to generate population-based thalamocortical pathway maps. The weighted fractional anisotropy and the longitudinal and transversal diffusivity of each pathway were calculated for individual participants. Patients with schizophrenia demonstrated decreased anisotropy and increased longitudinal and transversal diffusivity within the pathways from the mediodorsal nucleus and the pulvinar to the orbitofrontal and parietal-occipital-temporal lobes. Anisotropy decreases and diffusivity increases were correlated with positive and negative syndrome scale scores. Alterations in global diffusion properties within the thalamocortical pathways imply the disruption of brain circuitry in schizophrenic patients.

Orbitofrontal volume deficit in schizophrenia and thought disorder

Orbitofrontal Cortex (OFC) structural abnormality in schizophrenia has not been well characterized, probably due to marked anatomical variability and lack of consistent definitions. We previously reported OFC sulcogyral pattern alteration and its associations with social disturbance in schizophrenia, but OFC volume associations with psychopathology and cognition have not been investigated. We compared chronically treated schizophrenia patients with healthy control (HC) subjects, using a novel, reliable parcellation of OFC subregions and their association with cognition, especially the Iowa Gambling Task (IGT), and with schizophrenic psychopathology including thought disorder. Twenty-four patients with schizophrenia and 25 age-matched HC subjects underwent MRI. OFC Regions of Interest (ROI) were manually delineated according to anatomical boundaries: Gyrus Rectus (GR); Middle Orbital Gyrus (MiOG); and Lateral Orbital Gyrus (LOG). The OFC sulcogyral pattern was also classified. Additionally, MiOG probability maps were created and compared between groups in a voxel-wise manner. Both groups underwent cognitive evaluations using the IGT, Wisconsin Card Sorting Test, and Trail Making Test (TMT). An 11% bilaterally smaller MiOG volume was observed in schizophrenia, compared with HC (F(1,47) = 17.4, P = 0.0001). GR and LOG did not differ, although GR showed a rightward asymmetry in both groups (F(1,47) = 19.2, P < 0.0001). The smaller MiOG volume was independent of the OFC sulcogyral pattern, which differed in schizophrenia and HC (chi2 = 12.49, P = 0.002). A comparison of MiOG probability maps suggested that the anterior heteromodal region was more affected in the schizophrenia group than the posterior paralimbic region. In the schizophrenia group, a smaller left MiOG was strongly associated with worse 'positive formal thought disorder' (r = -0.638, P = 0.001), and a smaller right MiOG with a longer duration of the illness (r = -0.618, P = 0.002). While schizophrenics showed poorer performance than HC in the IGT, performance was not correlated with OFC volume. However, within the HC group, the larger the right hemisphere MiOG volume, the better the performance in the IGT (r = 0.541, P = 0.005), and the larger the left hemisphere volume, the faster the switching attention performance for the TMT, Trails B (r = -0.608, P = 0.003). The present study, applying a new anatomical parcellation method, demonstrated a subregion-specific OFC grey matter volume deficit in patients with schizophrenia, which was independent of OFC sulcogyral pattern. This volume deficit was associated with a longer duration of illness and greater formal thought disorder. In HC the finding of a quantitative association between OFC volume and IGT performance constitutes, to our knowledge, the first report of this association.

Volumetric abnormalities in connectivity-based subregions of the thalamus in patients with chronic schizophrenia

OBJECTIVE

The thalamus, which consists of multiple subnuclei, has been of particular interest in the study of schizophrenia. This study aimed to identify abnormalities in the connectivity-based subregions of the thalamus in patients with schizophrenia.

METHODS

Thalamic volume was measured by a manual tracing on superimposed images of T1-weighted and diffusion tensor images in 30 patients with schizophrenia and 22 normal volunteers. Cortical regional volumes automatically measured by a surface-based approach and thalamic subregional volumes measured by a connectivity-based technique were compared between the two groups and their correlations between the connected regions were calculated in each group.

RESULTS

Volume reduction was observed in the bilateral orbitofrontal cortices and the left cingulate gyrus on the cortical side, whereas in subregions connected to the right orbitofrontal cortex and bilateral parietal cortices on the thalamic side. Significant volumetric correlations were identified between the right dorsal prefrontal cortex and its related thalamic subregion and between the left parietal cortex and its related thalamic subregion only in the normal group.

CONCLUSIONS

Our results suggest that patients with schizophrenia have a structural deficit in the corticothalamic systems, especially in the orbitofrontal-thalamic system. Our findings may present evidence of corticothalamic connection problems in schizophrenia.