Hallucinations, thought disorders, and the language domain in schizophrenia

White matter tracts differentially associated with auditory hallucinations in first-episode psychosis: A correlational tractography diffusion spectrum imaging study

Auditory hallucinations (AH) are a debilitating symptom in psychosis, impacting cognition and real world functioning. Recent thought conceptualizes AH as a consequence of long-range brain communication dysfunction, or circuitopathy, within the auditory sensory/perceptual, language, and cognitive control systems. Recently we showed in first-episode psychosis (FEP) that, despite overall intact white matter integrity in the cortical-cortical and cortical-subcortical language tracts and the callosal tracts connecting auditory cortices, the severity of AH correlated inversely with white matter integrity. However, that hypothesis-driven isolation of specific tracts likely missed important white matter concomitants of AH. In this report, we used a whole-brain data-driven dimensional approach using correlational tractography to associate AH severity with white matter integrity in a sample of 175 individuals. Diffusion Spectrum Imaging (DSI) was used to image diffusion distribution. Quantitative Anisotropy (QA) in three tracts was greater with increased AH severity (FDR < 0.001) and QA in three tracts was lower with increased AH severity (FDR < 0.01). White matter tracts showing associations between QA and AH were generally associated with frontal-parietal-temporal connectivity (tracts with known relevance for cognitive control and the language system), in the cingulum bundle, and in prefrontal inter-hemispheric connectivity. The results of this whole brain data-driven analysis suggest that subtle white matter alterations connecting frontal, parietal, and temporal lobes in the service of sensory-perceptual, language/semantic, and cognitive control processes impact the expression of auditory hallucination in FEP. Disentangling the distributed neural circuits involved in AH should help to develop novel interventions, such as non-invasive brain stimulation.

Language Network Dysfunction and Formal Thought Disorder in Schizophrenia

BACKGROUND

Pathophysiological inquiries into schizophrenia require a consideration of one of its most defining features: disorganization and impoverishment in verbal behavior. This feature, often captured using the term Formal Thought Disorder (FTD), still remains to be one of the most poorly understood and understudied dimensions of schizophrenia. In particular, the large-scale network level dysfunction that contributes to FTD remains obscure to date.

STUDY DESIGN

In this narrative review, we consider the various challenges that need to be addressed for us to move towards mapping FTD (construct) to a brain network level account (circuit).

STUDY RESULTS

The construct-to-circuit mapping goal is now becoming more plausible than it ever was, given the parallel advent of brain stimulation and the tools providing objective readouts of human speech. Notwithstanding this, several challenges remain to be overcome before we can decisively map the neural basis of FTD. We highlight the need for phenotype refinement, robust experimental designs, informed analytical choices, and present plausible targets in and beyond the Language Network for brain stimulation studies in FTD.

CONCLUSIONS

Developing a therapeutically beneficial pathophysiological model of FTD is a challenging endeavor, but holds the promise of improving interpersonal communication and reducing social disability in schizophrenia. Addressing the issues raised in this review will be a decisive step in this direction.

Language abnormalities in schizophrenia: binding core symptoms through contemporary empirical evidence

Both the ability to speak and to infer complex linguistic messages from sounds have been claimed as uniquely human phenomena. In schizophrenia, formal thought disorder (FTD) and auditory verbal hallucinations (AVHs) are manifestations respectively relating to concrete disruptions of those abilities. From an evolutionary perspective, Crow (1997) proposed that "schizophrenia is the price that Homo sapiens pays for the faculty of language". Epidemiological and experimental evidence points to an overlap between FTD and AVHs, yet a thorough investigation examining their shared neural mechanism in schizophrenia is lacking. In this review, we synthesize observations from three key domains. First, neuroanatomical evidence indicates substantial shared abnormalities in language-processing regions between FTD and AVHs, even in the early phases of schizophrenia. Second, neurochemical studies point to a glutamate-related dysfunction in these language-processing brain regions, contributing to verbal production deficits. Third, genetic findings further show how genes that overlap between schizophrenia and language disorders influence neurodevelopment and neurotransmission. We argue that these observations converge into the possibility that a glutamatergic dysfunction in language-processing brain regions might be a shared neural basis of both FTD and AVHs. Investigations of language pathology in schizophrenia could facilitate the development of diagnostic tools and treatments, so we call for multilevel confirmatory analyses focused on modulations of the language network as a therapeutic goal in schizophrenia.

Pathological resting-state executive and language system perfusion in first-episode psychosis

BACKGROUND AND HYPOTHESIS

Cortical (e.g., Broca's area and Wernicke's area) and subcortical (e.g., putamen) language-related areas and executive control areas (e.g., inferior frontal gyrus (IFG), dorsolateral prefrontal cortex (DLPFC)) show functional and structural dysconnectivity in long-term psychosis. We examined whether resting-state basal perfusion levels revealed selective pathophysiology (likely hypo- and hyper-activation) of language-related and executive areas in first-episode psychosis (FEP).

STUDY DESIGN

Basal resting-state perfusion was measured using pseudo-continuous Arterial Spin Labeling (pcASL). Relative cerebral blood flow (rCBF) was compared between 32 FEP and 34 matched healthy comparison (HC) individuals. Structural and functional MRI scans were acquired using a 3T Prisma scanner during the same session.

STUDY RESULTS

Whole-brain comparison of resting rCBF identified 8 clusters with significant between-group differences. Reduced rCBF was found in executive control areas in left and right IFG, right DLPFC, and right parietal cortex. Increased rCBF was found in left and right temporal cortex (including Wernicke's area), and left and right putamen. A positive correlation was observed between auditory hallucination severity and rCBF in the left putamen.

CONCLUSIONS

To the degree that perfusion implies activation, language and auditory processing areas in bilateral temporal lobe and putamen showed pathological hyper-activity, and cognitive control areas (IFG, DLPFC, right parietal) showed pathological hypo-activity in FEP at rest. Pathological basal activity was present across the range of symptom severity, suggesting it may be a common underlying pathology for psychosis that may be targeted with non-invasive brain stimulation to normalize resting activity levels.

Organized Resting-state Functional Dysconnectivity of the Prefrontal Cortex in Patients with Schizophrenia

Schizophrenia has prominent functional dysconnectivity, especially in the prefrontal cortex (PFC). However, it is unclear whether in the same group of patients with schizophrenia, PFC functional dysconnectivity appears in an organized manner or is stochastically located in different subregions. By investigating the resting-state functional connectivity (rsFC) of each PFC subregion from the Brainnetome atlas in 40 schizophrenia patients and 40 healthy subjects, we found 24 altered connections in schizophrenia, and the connections were divided into four categories by a clustering analysis: increased connections within the PFC, increased connections between the inferior PFC and the thalamus/striatum, reduced connections between the PFC and the motor control areas, and reduced connections between the orbital PFC and the emotional perception regions. In addition, the four categories of rsFC showed distinct cognitive engagement patterns. Our findings suggest that PFC subregions have specific functional dysconnectivity patterns in schizophrenia and may reflect heterogeneous symptoms and cognitive deficits in schizophrenia.

P300-mediated modulations in self-other processing under psychedelic psilocybin are related to connectedness and changed meaning: A window into the self-other overlap

The concept of self and self‐referential processing has a growing explanatory value in psychiatry and neuroscience, referring to the cognitive organization and perceptual differentiation of self‐stimuli in health and disease. Conditions in which selfhood loses its natural coherence offer a unique opportunity for elucidating the mechanisms underlying self‐disturbances. We assessed the psychoactive effects of psilocybin (230 μg/kg p.o.), a preferential 5‐HT1A/2A agonist known to induce shifts in self‐perception. Our placebo‐controlled, double‐blind, within‐subject crossover experiment (n = 17) implemented a verbal self‐monitoring task involving vocalizations and participant identification of real‐time auditory source‐ (self/other) and pitch‐modulating feedback. Subjective experience and task performance were analyzed, with time‐point‐by‐time‐point assumption‐free multivariate randomization statistics applied to the spatiotemporal dynamics of event‐related potentials. Psilocybin‐modulated self‐experience, interacted with source to affect task accuracy, and altered the late phase of self‐stimuli encoding by abolishing the distinctiveness of self‐ and other‐related electric field configurations during the P300 timeframe. This last effect was driven by current source density changes within the supragenual anterior cingulate and right insular cortex. The extent of the P300 effect was associated with the intensity of psilocybin‐induced feelings of unity and changed meaning of percepts. Modulations of late encoding and their underlying neural generators in self‐referential processing networks via 5‐HT signaling may be key for understanding self‐disorders. This mechanism may reflect a neural instantiation of altered self–other and relational meaning processing in a stimulus‐locked time domain. The study elucidates the neuropharmacological foundation of subjectivity, with implications for therapy, underscoring the concept of connectedness.

White Matter Microstructural Abnormalities in the Broca's-Wernicke's-Putamen "Hoffman Hallucination Circuit" and Auditory Transcallosal Fibers in First-Episode Psychosis With Auditory Hallucinations

BACKGROUND

Functional connectivity abnormalities between Broca's and Wernicke's areas and the putamen revealed by functional magnetic resonance imaging (fMRI) are related to auditory hallucinations (AH). In long-term schizophrenia, reduced white matter structural integrity revealed by diffusion imaging in left arcuate fasciculus (connecting Broca's and Wernicke's areas) is likely related to AH. The structural integrity of connections with putamen and their relation to AH are unknown. Little is known about this relationship in first-episode psychosis (FEP), although auditory transcallosal connections were reported to play a role. White matter in the Broca's-Wernicke's-putamen language-related circuit and auditory transcallosal fibers was examined to investigate associations with AH in FEP.

METHODS

White matter connectivity was measured in 40 FEP and 32 matched HC using generalized fractional anisotropy (gFA) derived from diffusion spectrum imaging (DSI).

RESULTS

FEP and HC did not differ in gFA in any fiber bundle. In FEP, AH severity was significantly inversely related to gFA in auditory transcallosal fibers and left arcuate fasciculus. Although the right hemisphere arcuate fasciculus-AH association did not attain significance, the left and right arcuate fasciculus associations were not significantly different.

CONCLUSIONS

Despite overall normal gFA in FEP, AH severity was significantly related to gFA in transcallosal auditory fibers and the left hemisphere connection between Broca's and Wernicke's areas. Other bilateral tracts' gFA were weakly associated with AH. At the first psychotic episode, AH are more robustly associated with left hemisphere arcuate fasciculus and interhemispheric auditory fibers microstructural deficits, likely reflecting mistiming of information flow between language-related cortical centers.

Diffusion kurtosis imaging of gray matter in schizophrenia

Prior postmortem studies have shown gray matter (GM) microstructural abnormalities in schizophrenia. However, few studies to date have examined GM microstructural integrity in schizophrenia in vivo. Here, we employed diffusion kurtosis imaging (DKI) to test for differences in GM microstructure in eighteen schizophrenia (SZ) patients versus nineteen healthy controls (HC). GM microstructure was characterized in each participant using DKI-derived metrics of mean kurtosis (MK) and mean diffusivity (MD). Individual T1-weighted images were used to create subject-specific cortically-labelled regions of interest (ROIs) of the four cortical lobes and sixty-eight cortical GM regions delineated by the Desikan-Killiany atlas, and to derive the associated cortical thickness and area measures. The derived ROIs were also registered to the diffusion space of each subject and used to generate region-specific mean MK and MD values. We additionally administered the Wisconsin Card Sorting Test (WCST), Stroop test, and Trail Making Test part B (Trails-B) to test the relationship between GM metrics and executive function in SZ. We found significantly increased MK and MD in SZ compared to HC participants in the temporal lobe, sub-lobar temporal cortical regions (fusiform, inferior temporal, middle temporal and temporal pole), and posterior cingulate cortex after correcting for multiple comparisons. Correlational analyses revealed significant associations of MK and MD with executive function scores derived from the WCST, Stroop, and Trails-B tests, along with an inverse relationship between MK and MD and cortical thickness and area. A hierarchical multiple linear regression analysis showed that up to 85% of the inter-subject variability in cognitive function in schizophrenia measured by the WCST could be explained by MK in combination with either GM thickness or area. MK and MD appear to be sensitive to GM microstructural pathology in schizophrenia and may provide useful biomarkers of abnormal cortical microstructure in this disorder.

Altered syntactic abilities in first episode patients: An inner phenomenon characterizing psychosis

BACKGROUND

Research has consistently shown that language abilities represent a core dimension of psychosis; however, to date, very little is known about syntactic comprehension performance in the early stages of psychosis. This study aims to compare the linguistic abilities involved in syntactic comprehension in a large group of First Episode Psychosis (FEP) patients and healthy controls (HCs).

METHODS

A multiple choice test of comprehension of syntax was administered to 218 FEP patients (166 non-affective FEP patients [FEP-NA] and 52 affective FEP patients [FEP-A]) and 106 HCs. All participants were asked to match a sentence they listen with one out of four vignettes on a pc screen. Only one vignette represents the stimulus target, while the others are grammatical or non-grammatical (visual) distractors. Both grammatical and non-grammatical errors and performance in different syntactic constructions were considered.

RESULTS

FEP committed greater number of errors in the majority of TCGB language domains compared to HCs. Moreover, FEP-NA patients committed significantly more non-grammatical (z = -3.2, p = 0.007), locative (z = -4.7, p < 0.001), passive-negative (z = -3.2, p = 0.02), and relative (z = -4.6, p < 0.001) errors compared to HCs as well as more passive-affirmative errors compared to both HCs (z = -4.3, p < 0.001) and FEP-A (z = 3.1, p = 0.04). Finally, we also found that both FEP-NA and FEP-A committed more grammatical (FEP-NA: z = -9.2, p < 0.001 and FEP-A: z = -4.4, p < 0.001), total (FEP-NA: z = -8.2, p < 0.001 and FEP-A: z = 3.9, p =  0.002), and active-negative (FEP-NA: z = -5.8, p < 0.001 and FEP-A: z = -3.5, p = 0.01) errors compared to HCs.

CONCLUSIONS

This study shows that the access to syntactic structures is already impaired in FEP patients, especially in those with FEP-NA, ultimately suggesting that language impairments represent a core and inner feature of psychosis even at early stages.

Formal thought disorder is related to aberrations in language-related white matter tracts in patients with schizophrenia

This study examined the hypothesis that a fronto-temporal disconnection in the language network underpins formal thought disorder (FTD) in schizophrenia. Forty-nine patients with a schizophrenia spectrum disorder (27 with mild FTD, 22 with severe FTD) and 26 healthy controls (HC) were included. Overall psychopathology and FTD were assessed by the Positive and Negative Syndrome Scale and the Thought, Language, and Communication scale, respectively. White matter (WM) microstructure was analysed using Tract-Based Spatial Statistics. In patients, severity of overall FTD (TLC Sum Score) was predicted by decreased fractional anisotropy (FA) in the right superior longitudinal fasciculus (SLF), and severity of negative FTD (TLC Emptiness subscale) was predicted by increased FA in the left SLF and arcuate fasciculus (AF). Notably, these results were no longer significant after correction for multiple comparisons. Compared with HC, patients showed lower FA in all the investigated language-related WM tracts as well as across the whole WM skeleton. No difference in FA was found between patients with severe and patients with mild FTD. Our results are compatible with earlier studies reporting impairments in widely spread WM tracts including those related to language processing in patients with schizophrenia.

Is formal thought disorder in schizophrenia related to structural and functional aberrations in the language network? A systematic review of neuroimaging findings

Formal thought disorder (FTD) is a core feature of schizophrenia, a marker of illness severity and a predictor of outcome. The underlying neural mechanisms are still a matter of debate. This study aimed at 1) reviewing the literature on the neural correlates of FTD in schizophrenia, and 2) testing the hypothesis that FTD correlates with structural and functional aberrations in the language network. Medline, PsychInfo, and Embase were searched for neuroimaging studies, which applied a clinical measure to assess FTD in adults with schizophrenia and were published in English or German in peer-reviewed journals until December 2016. Of 412 articles identified, 61 studies were included in the review. Volumetric studies reported bilateral grey matter deficits (L > R) to be associated with FTD in the inferior frontal gyrus, the superior temporal gyrus and the inferior parietal lobe. The same regions showed hyperactivity in resting state functional magnetic resonance imaging (fMRI) studies and both hyper- and hypoactivity in fMRI studies that employed semantic processing or free speech production tasks. Diffusion tensor imaging studies demonstrated white matter aberrations in fibre tracts that connect the frontal and temporo-parietal regions. FTD in schizophrenia was found to be associated with structural and functional aberrations in the language network. However, there are studies that did not find an association between FTD and neural aberrations of the language network and regions not included in the language network have been associated with FTD. Thus, future research is needed to clarify the specificity of the language network for FTD in schizophrenia.

Systems Neuroscience of Psychosis: Mapping Schizophrenia Symptoms onto Brain Systems

Schizophrenia research has been in a deadlock for many decades. Despite important advances in clinical treatment, there are still major concerns regarding long-term psychosocial reintegration and disease management, biological heterogeneity, unsatisfactory predictors of individual course and treatment strategies, and a confusing variety of controversial theories about its etiology and pathophysiological mechanisms. In the present perspective on schizophrenia research, we first discuss a methodological pitfall in contemporary schizophrenia research inherent in the attempt to link mental phenomena with the brain: we claim that the time-honored phenomenological method of defining mental symptoms should not be contaminated with the naturalistic approach of modern neuroscience. We then describe our Systems Neuroscience of Psychosis (SyNoPsis) project, which aims to overcome this intrinsic problem of psychiatric research. Considering schizophrenia primarily as a disorder of interindividual communication, we developed a neurobiologically informed semiotics of psychotic disorders, as well as an operational clinical rating scale. The novel psychopathology allows disentangling the clinical manifestations of schizophrenia into behavioral domains matching the functions of three well-described higher-order corticobasal brain systems involved in interindividual human communication, namely, the limbic, associative, and motor loops, including their corticocortical sensorimotor connections. The results of several empirical studies support the hypothesis that the proposed three-dimensional symptom structure, segregated into the affective, the language, and the motor domain, can be specifically mapped onto structural and functional abnormalities of the respective brain systems. New pathophysiological hypotheses derived from this brain system-oriented approach have helped to develop and improve novel treatment strategies with noninvasive brain stimulation and practicable clinical parameters. In clinical practice, the novel psychopathology allows confining the communication deficits of the individual patient, shifting attention from the symptoms to the intact resources. We have studied this approach and observed important advantages for therapeutic alliances, personalized treatment, and de-escalation strategies. Future studies will further conjoin clinical definitions of psychotic symptoms with brain structures and functions, and disentangle structural and functional deficit patterns within these systems to identify neurobiologically distinct subsyndromes. Neurobiologically homogeneous patient groups may provide new momentum for treatment research. Finally, lessons learned from schizophrenia research may contribute to developing a comprehensive perspective on human experience and behavior that integrates methodologically distinct, but internally consistent, insights from humanities and neuroscience.

Segregating polymorphisms of FOXP2 are associated with measures of inner speech, speech fluency and strength of handedness in a healthy population

We genotyped a healthy population for three haplotype-tagging FOXP2 SNPs, and tested for associations of these SNPs with strength of handedness and questionnaire-based metrics of inner speech characteristics (ISP) and speech fluency (FLU), as derived from the Schizotypal Personality Questionnaire-BR. Levels of mixed-handedness were positively correlated with ISP and FLU, supporting prior work on these two domains. Genotype for rs7799109, a SNP previously linked with lateralization of left frontal regions underlying language, was associated with degree of mixed handedness and with scores for ISP and FLU phenotypes. Genotype of rs1456031, which has previously been linked with auditory hallucinations, was also associated with ISP phenotypes. These results provide evidence that FOXP2 SNPs influence aspects of human inner speech and fluency that are related to lateralized phenotypes, and suggest that the evolution of human language, as mediated by the adaptive evolution of FOXP2, involved features of inner speech.

Brain anatomy of symptom stratification in schizophrenia: a voxel-based morphometry study

BACKGROUND

Although some Magnetic Resonance Imaging (MRI) studies have investigated the relationship between clinical severity and neuroanatomical alterations in patients with schizophrenia (SCZ), the biological signature associated with illness severity in schizophrenia is still uncertain. Therefore, this study aims to investigate structural brain abnormalities in SCZ, with particular regards to the identification of potential deficits associated with the severity of illness.

METHODS

In total, 1.5T MRI data were acquired for 61 subjects with SCZ and 59 matched healthy controls (HC). The patient group was divided in two sub-groups based on clinical severity, one composed of 34 mild-to-moderately ill patients, and the other of 27 severely ill patients, and compared with matched HC.

RESULTS

The whole group of patients with SCZ had significantly reduced grey matter (GM) volumes in the left inferior and middle temporal gyrus compared to HC (p < 0.05, pFWE corrected). Furthermore, compared to HC, patients with mild-to-moderate illness showed decreased GM volumes in the inferior and middle temporal gyrus, whereas those with severe illness had reduced GM volumes in the middle temporal gyrus and cerebellum bilaterally (all p < 0.001 uncorrected). No differences were observed between the two sub-groups of patients.

CONCLUSION

The results showed significant GM volume reductions in temporal regions in patients with SCZ compared to matched HC, confirming the role of these regions in the pathophysiology of SCZ. Furthermore, specific cerebellar grey matter volume reductions were identified in patients with severe illness, which may contribute to stratifying patients with SCZ according to their clinical phenotype expression, ultimately helping in guiding targeted therapeutic/rehabilitation interventions.

Comparison of psychopathological dimensions between major depressive disorder and schizophrenia spectrum disorders focusing on language, affectivity and motor behavior

This study tested whether patients with major depressive disorder (MDD) and schizophrenia spectrum disorders would differ in three dimensions of psychopathology (language, affectivity and motor behavior) as assessed by the Bern Psychopathology Scale (BPS) in a cohort of 58 patients with MDD and 146 patients with schizophrenia spectrum disorders. The overall estimation of severity of each of the three dimensions was rated on a seven-point Likert scale from severely inhibited to severely disinhibited. Here, more than half of the patients endorsed ratings that showed normal or mildly (dis-)inhibited behavior. At group level more pronounced negative ratings of affect were seen in MDD. Group comparisons of the severity ratings on language or motor behavior yielded no differences between schizophrenia spectrum disorders and MDD. At the individuals' levels, extreme ratings in the language and motor dimensions were more frequent in schizophrenia spectrum disorders and in the affectivity dimension more frequent in MDD. Shared psychopathological features could be seen across diagnoses, supporting a dimensional approach to psychopathology in endogenous psychoses. However, the groups differ in the severity of affect ratings as well as in the distribution of language, affectivity and motor ratings with more variance among the group of schizophrenia spectrum disorders.

Increased Resting-State Gamma-Band Connectivity in First-Episode Schizophrenia

BACKGROUND

Schizophrenia has long been suggested to represent a disorder with prominent neural dysconnectivity. Gamma-band oscillations are highly relevant in this context, due both to their proposed involvement in neuronal synchronization and to their association with neurotransmitter systems relevant for schizophrenia. Several task-related studies have confirmed reduced power and synchronization of gamma-band oscillations in schizophrenia, but it has been suggested that these findings might not apply to the resting state. The present study aimed to investigate resting-state gamma-band connectivity in patients with schizophrenia.

METHODS

Sixty-four channel resting-state electroencephalography (eyes closed) was recorded in 22 patients with first-episode schizophrenia and 22 healthy controls matched for age and gender. Orthogonalized power envelope correlation was used as a measure of connectivity across 80 cortical regions at 40 Hz. Mean connectivity at each region was compared across groups using the nonparametric randomization approach. Additionally, the network-based statistic was applied to identify affected networks in patients.

RESULTS

Patients displayed increased mean functional gamma-band connectivity compared to controls in the left rolandic operculum. Network-based analyses indicated increased connectivity in patients within a strongly lateralized network consisting mainly of left inferior frontal/orbitofrontal, lateral and medial temporal, and inferior parietal areas. Within this network, gamma-band connectivity was higher in patients with low positive and disorganization symptom levels.

CONCLUSIONS

The present study provides a link between resting-state gamma-band connectivity and the core symptoms of schizophrenia. The observed findings are different than those reported by task-related studies, suggesting that resting-state studies might reveal new aspects in the pathophysiology of schizophrenia.

Lexical use in emotional autobiographical narratives of persons with schizophrenia and healthy controls

Language dysfunction has long been described in schizophrenia and most studies have focused on characteristics of structure and form. This project focuses on the content of language based on autobiographical narratives of five basic emotions. In persons with schizophrenia and healthy controls, we employed a comprehensive automated analysis of lexical use and we identified specific words and semantically or functionally related words derived from dictionaries that occurred significantly more often in narratives of either group. Patients employed a similar number of words but differed in lower expressivity and complexity, more self-reference and more repetitions. We developed a classification method for predicting subject status and tested its accuracy in a leave-one-subject-out evaluation procedure. We identified a set of 18 features that achieved 65.7% accuracy in predicting clinical status based on single emotion narratives, and 74.4% accuracy based on all five narratives. Subject clinical status could be determined automatically more accurately based on narratives related to anger or happiness experiences and there were a larger number of lexical differences between the two groups for these emotions compared to other emotions.

Executive function as predictors of persistent thought disorder in first-episode schizophrenia: a one-year follow-up study

Language disorganization is an important clinical indicator of acute psychosis, yet the longitudinal course and pathogenesis are not well understood. Executive dysfunction has been suggested as a vital contributor to formal thought disorder (FTD) and may serve as a stable predictor of symptomatic risk. The paper reports a one-year prospective study of language disorganization in sixty patients with first-episode schizophrenia-spectrum disorders and investigates executive function as a predictor of persistent FTD one year after illness onset. FTD was captured using the Clinical Language Disorder Rating Scale (CLANG), which segregates language abnormalities into three empirically validated levels: syntactic, semantic, and production. After one year, patients' syntactic and semantic deficits were substantially reduced, but production impairments persisted. Patients' improvement of semantic impairment was associated with reduced disorganized symptoms while production impairment was associated with negative symptoms. We further identified two different patterns of baseline executive function predictors for both residual semantic and production impairment. We found that sustained FTD at the semantic level was predicted by both sustained attention and planning at illness onset, while residual production failure was only predicted by sustained attention. In conclusion, the present paper documents the distinct characteristics of psycholinguistic levels in FTD and isolates two different patterns of executive function predictors for persistent semantic and production language disorganization at follow-up. The findings help to disentangle FTD dimensions at different levels of language production processes, which provide clinical implications for targeting patients at risk for prolonged FTD concordant upon executive dysfunction at illness onset.

Ventral striatum gray matter density reduction in patients with schizophrenia and psychotic emotional dysregulation

Introduction

Substantial heterogeneity remains across studies investigating changes in gray matter in schizophrenia. Differences in methodology, heterogeneous symptom patterns and symptom trajectories may contribute to inconsistent findings. To address this problem, we recently proposed to group patients by symptom dimensions, which map on the language, the limbic and the motor systems. The aim of the present study was to investigate whether patients with prevalent symptoms of emotional dysregulation would show structural neuronal abnormalities in the limbic system.

Method

43 right-handed medicated patients with schizophrenia were assessed with the Bern Psychopathology Scale (BPS). The patients and a control group of 34 healthy individuals underwent structural imaging at a 3T MRI scanner. Whole brain voxel-based morphometry (VBM) was compared between patient subgroups with different severity of emotional dysregulation. Group comparisons (comparison between patients with severe emotional dysregulation, patients with mild emotional dysregulation, patients with no emotional dysregulation and healthy controls) were performed using a one way ANOVA and ANCOVA respectively.

Results

Patients with severe emotional dysregulation had significantly decreased gray matter density in a large cluster including the right ventral striatum and the head of the caudate compared to patients without emotional dysregulation. Comparing patients with severe emotional dysregulation and healthy controls, several clusters of significant decreased GM density were detected in patients, including the right ventral striatum, head of the caudate, left hippocampus, bilateral thalamus, dorsolateral prefrontal and orbitofrontal cortex. The significant effect in the ventral striatum was lost when patients with and without emotional dysregulation were pooled and compared with controls.

Discussion

Decreased gray matter density in a large cluster including the right ventral striatum was associated with severe symptoms of emotional dysregulation in patients with schizophrenia. The ventral striatum is an important part of the limbic system, and was indicated to be involved in the generation of incentive salience and psychotic symptoms. Only patients with severe emotional dysregulation had decreased gray matter in several brain structures associated with emotion and reward processing compared to healthy controls. The results support the hypothesis that grouping patients according to specific clinical symptoms matched to the limbic system allows identifying patient subgroups with structural abnormalities in the limbic network.

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We examined whole brain VBM in schizophrenia patients and healthy controls.

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We compared patients with different severity of emotional dysregulation (ED).

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Symptoms of ED were associated with GM density in the ventral striatum.

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Grouping patients according to symptoms identified specific GM abnormalities.

Functional MRI of sentence-level language comprehension in schizophrenia: a coordinate-based analysis

Numerous authors have hypothesised that abnormal pathways for language play a key role in the pathophysiology of schizophrenia, a notion that is supported by structural imaging and post-mortem findings especially in patients with thought disorder and auditory verbal hallucinations. Recently, an increasing number of functional magnetic resonance imaging (fMRI) investigations addressed language comprehension schizophrenia. We present a systematic review of the fMRI-studies on sentence- and text-level language comprehension in schizophrenia. 13 studies met the inclusion criteria. Additional studies specifically addressed language lateralization. Coordinates for differential contrasts for healthy controls>patients reported in these studies indicate that the left fronto-temporal language network is altered in schizophrenia. 33 out of the 51 reported coordinates are located in the left hemisphere. Overactivation in schizophrenia extends into premotor areas and is about equally divided among the left and right hemispheres. Several negative studies indicate heterogeneity within schizophrenia, which could possibly be related to the severity of thought disorder or auditory verbal hallucinations of patients. Activation changes related to thought disorder within schizophrenia (n=4 studies) include the inferior frontal and superior temporal gyri and are moderately lateralized to the left hemisphere. Although current fMRI literature is still insufficient to draw decisive conclusions, results point towards functionally altered pathways for language in schizophrenia. This notion is also plausible from the viewpoint of psychopathology especially since hallmark symptoms of the disease, thought disorder, auditory verbal hallucinations and alogia, are expressed in terms of language or represent abnormalities of language function.

Genetic influences of resting state fMRI activity in language-related brain regions in healthy controls and schizophrenia patients: a pilot study

Individuals with schizophrenia show a broad range of language impairments, similar to those observed in reading disability (RD). Genetic linkage and association studies of RD have identified a number of candidate RD-genes that are associated with neuronal migration. Some individuals with schizophrenia also show evidence of impaired cortical neuronal migration. We have previously linked RD-related genes with gray matter distributions in healthy controls and schizophrenia. The aim of the current study was to extend these structural findings and to examine links between putative RD-genes and functional connectivity of language-related regions in healthy controls (n = 27) and schizophrenia (n = 28). Parallel independent component analysis (parallel-ICA) was used to examine the relationship between language-related regions extracted from resting-state fMRI and 16 single nucleotide polymorphisms (SNPs) spanning 5 RD-related genes. Parallel-ICA identified four significant fMRI-SNP relationships. A Left Broca-Superior/Inferior Parietal network was related to two KIAA0319 SNPs in controls but not in schizophrenia. For both diagnostic groups, a Broca-Medial Parietal network was related to two DCDC2 SNPs, while a Left Wernicke-Fronto-Occipital network was related to two KIAA0319 SNPs. A Bilateral Wernicke-Fronto-Parietal network was related to one KIAA0319 SNP only in controls. Thus, RD-genes influence functional connectivity in language-related regions, but no RD-gene uniquely affected network function in schizophrenia as compared to controls. This is in contrast with our previous study where RD-genes affected gray matter distribution in some structural networks in schizophrenia but not in controls. Thus these RD-genes may exert a more important influence on structure rather than function of language-related networks in schizophrenia.

Network analysis of auditory hallucinations in nonpsychotic individuals

BACKGROUND

Auditory verbal hallucinations (AVH) are a cardinal feature of schizophrenia and can severely disrupt behavior and decrease quality of life. Identification of areas with high functional connectivity (so-called hub regions) that are associated with the predisposition to hallucinate may provide potential targets for neuromodulation in the treatment of AVH.

METHODS

Resting-state fMRI scans during which no hallucinations had occurred were acquired from 29 nonpsychotic individuals with AVH and 29 matched controls. These nonpsychotic individuals with AVH provide the opportunity to study AVH without several confounds associated with schizophrenia, such as antipsychotic medication use and other symptoms related to the illness. Hub regions were identified by assessing weighted connectivity strength and betweenness centrality across groups using a permutation analysis.

RESULTS

Nonpsychotic individuals with AVH exhibited increased functioning as hub regions in the temporal cortices and the posterior cingulate/precuneus, which is an important area in the default mode network (DMN), compared to the nonhallucinating controls. In addition, the right inferior temporal gyrus, left paracentral lobule and right amygdala were less important as a hub region in the AVH group.

CONCLUSIONS

These results suggest that the predisposition to hallucinate may be related to aberrant functioning of the DMN and the auditory cortices.

Semantic network disconnection in formal thought disorder

BACKGROUND

Structural and functional findings in schizophrenic patients with formal thought disorder (FTD) show abnormalities within left-side semantic areas. The present study investigate the network function of the involved brain regions as a function of FTD severity.

METHODS

We examined a group of 16 schizophrenia patients differing in FTD, but not in overall symptom severity, and 18 matched healthy controls. A passive word reading paradigm was applied during functional MRI (fMRI). A concatenated independent component analysis approach separated the fMRI signal into independent components, and spatial similarity was used to estimate the individual differences in spatial configuration of networks.

RESULTS

The semantic network was identified for both groups encompassing structures of the left inferior frontal gyrus, the left angular gyrus and the left middle temporal gyrus. The differences between the semantic networks of patients and controls increased with increasing severity of FTD. This difference was due to a decreasing contribution of the left inferior frontal gyrus (Brodmann area 45 and 47).

CONCLUSION

Severity of FTD was correlated with a disruption of the left semantic network in schizophrenic patients. We suggest that FTD is a consequence of a frontal-parietal/temporal disconnection due to a complex interaction between structural and functional abnormalities within the left semantic network.

Auditory verbal hallucinations: imaging, analysis, and intervention

In this article, we will link neuroimaging, data analysis, and intervention methods in an important psychiatric condition: auditory verbal hallucinations (AVH). The clinical and phenomenological background as well as neurophysiological findings will be covered and discussed with respect to noninvasive brain stimulation. Additionally, methods of noninvasive brain stimulation will be presented as ways to intervene with AVH. Finally, preliminary conclusions and possible future perspectives will be proposed.

Modeling ketamine effects on synaptic plasticity during the mismatch negativity

This paper presents a model-based investigation of mechanisms underlying the reduction of mismatch negativity (MMN) amplitudes under the NMDA-receptor antagonist ketamine. We applied dynamic causal modeling and Bayesian model selection to data from a recent ketamine study of the roving MMN paradigm, using a cross-over, double-blind, placebo-controlled design. Our modeling was guided by a predictive coding framework that unifies contemporary "adaptation" and "model adjustment" MMN theories. Comparing a series of dynamic causal models that allowed for different expressions of neuronal adaptation and synaptic plasticity, we obtained 3 major results: 1) We replicated previous results that both adaptation and short-term plasticity are necessary to explain MMN generation per se; 2) we found significant ketamine effects on synaptic plasticity, but not adaptation, and a selective ketamine effect on the forward connection from left primary auditory cortex to superior temporal gyrus; 3) this model-based estimate of ketamine effects on synaptic plasticity correlated significantly with ratings of ketamine-induced impairments in cognition and control. Our modeling approach thus suggests a concrete mechanism for ketamine effects on MMN that correlates with drug-induced psychopathology. More generally, this demonstrates the potential of modeling for inferring on synaptic physiology, and its pharmacological modulation, from electroencephalography data.

Possible dysregulation of cortical plasticity in auditory verbal hallucinations-A cortical thickness study in schizophrenia

INTRODUCTION

Investigations of gray matter changes in relation with auditory verbal hallucinations (AVH) have reported conflicting results. Assuming that alterations in gray matter might be related to certain symptoms in schizophrenia this study aimed to investigate changes in cortical thickness specific to AVH. It was hypothesized that schizophrenia patients suffering from persistent AVH would show significant differences in cortical thickness in regions involved in language-production and perception when compared to schizophrenia patients which had never experienced any hallucinations.

METHODS

Using cortical thickness analysis the present study investigated ten schizophrenic patients suffering from AVH, ten non-hallucinating schizophrenic patients, and ten healthy control subjects. Anatomical data were acquired on a 3 T MRI system, transformed into standard space and cortically aligned to investigate local differences in whole brain cortical thickness between the two patient groups. Based on this comparison, brain regions with alterations specific for the patients with AVH were identified and then used as regions of interest to compare both patient groups to the healthy subjects respectively.

RESULTS

Hallucinating patients showed gray matter reductions in the dominant hemisphere predominantly in sensory language areas relevant for speech processing. Increased cortical thickness was found in regions related to self-monitoring.

CONCLUSIONS

Gray matter reductions in chronic schizophrenic patients may be the sequel of synaptic derangement or disease-related deregulation of language circuits. In order to clarify the ambiguous information processing additional demands might be put on cortical structures responsible for self-monitoring processes leading to changes in cortical thickness in the sense of neural plasticity.

Genetic influences of cortical gray matter in language-related regions in healthy controls and schizophrenia

Individuals with schizophrenia show a broad range of language impairments, including reading difficulties. A recent structural MRI (sMRI) study linked these difficulties to structural abnormalities in language-related regions (Leonard et al., 2008). Similar regions have been implicated in primary reading disability (RD). Major hypotheses of RD implicate abnormal embryonic neuronal migration in the cortex, and genetic linkage and association studies have identified a number of candidate RD genes that are associated with neuronal migration (Paracchini et al., 2007). Interestingly, evidence suggests at least some individuals with schizophrenia also show impaired neuronal migration in the cortex (Akbarian et al., 1996). Thus the aim of this study was to examine the link between RD-related genes and gray matter volumes in healthy controls and schizophrenia. We used parallel independent component analysis (parallel-ICA) to examine the relationship between gray matter volumes extracted using voxel-based morphometry (VBM) and 16 single nucleotide polymorphisms (SNPs) spanning FOXP2 and four RD-related genes, DCDC2, DYX1C1, KIAA0319 and TTRAP. Parallel-ICA identified five sMRI-SNP relationships. Superior and inferior cerebellar networks were related to DYX1C1 and DCDC2/KIAA0319 respectively in both groups. The superior prefrontal, temporal and occipital networks were positively related to DCDC2 in the schizophrenia, but not the control group. The identified networks closely correspond to the known distribution of language processes in the cortex. Thus, reading and language difficulties in schizophrenia may be related to distributed cortical structural abnormalities associated with RD-related genes.

Disrupted white matter integrity of corticopontine-cerebellar circuitry in schizophrenia

Evidence for white matter abnormalities in patients with schizophrenia is increasing. Decreased fractional anisotropy (FA) in interhemispheric commissural fibers as well as long-ranging fronto-parietal association fibers belongs to the most frequent findings. The present study used tract-based spatial statistics to investigate white matter integrity in 35 patients with schizophrenia and 35 healthy volunteers. We found that patients exhibited significantly decreased FA relative to healthy subjects in the corpus callosum, the cerebral peduncle, the left inferior fronto-occipital fasciculus, the anterior thalamic radiation, the right posterior corona radiata, the middle cerebellar peduncle, and the right superior longitudinal fasciculus. Increased FA was detectable in the inferior sections of the corticopontine-cerebellar circuit. Present data indicate extended cortical-subcortical alterations of white matter integrity in schizophrenia using advanced data analysis strategies. They corroborate preceding findings of white matter structural deficits in mainly long-ranging association fibers and provide first evidence for neuroplastic changes in terms of an increased directionality in more inferior fiber tracts.

Language pathway abnormalities in schizophrenia: a review of fMRI and other imaging studies

PURPOSE OF REVIEW

Schizophrenia is a severe mental disorder with substantial genetic vulnerability. This review discusses recent neuroimaging studies reporting on impairment in brain functioning relevant to language processing in individuals with schizophrenia and those who are at a genetic risk for its development.

RECENT FINDINGS

Studies have shown that schizophrenia is associated with deficits in language function, as well as structural and functional abnormalities in brain regions that are involved with language perception and processing. Individuals who are at genetic high risk for schizophrenia also have structural and functional deficits in brain pathways for language processing. These studies consistently suggest that the normal pattern of left hemisphere dominance of language processing is significantly disturbed.

SUMMARY

This review suggests that future studies should examine the underlying mechanism for producing this disturbance in language processing and that prospective studies should be carried out that aim to follow individuals over time to determine whether these anomalies eventually lead to clinical symptoms of schizophrenia.

Neurophysiological mechanisms of psychotic symptoms

Psychotic symptoms are supposed to be expression of highest order brain functions such as symbolic thinking, language, planning, empathy or complex emotional reactions. However, due to its historical roots, current psychiatric symptomatology is based on descriptions of disturbed behavior, which refer to metaphysic concepts rather than to brain function. Therefore, modern biological research suffers from an important gap between psychiatric semiology and contemporary knowledge in systems neurophysiology. The authors argue for a redefinition of psychiatric symptoms in a neurobiologically meaningful way. Based on recent empirical studies, this strategy is exemplified for auditory verbal hallucinations and formal thought disorder. In these examples, characteristic psychiatric symptoms can be related to circumscribed structural and functional alterations in the language system, allowing the description of clinical phenomena in terms of neurobiological events. This strategy is also applicable to other psychotic symptoms like emotional dysregulation and catatonia, where disturbances of the functional circuits of mood and motor regulation, respectively, are predicted. This approach to psychiatric symptoms is based on contemporary evidence concerning systems neurophysiology and is expected to provide meaningful and testable hypotheses for future research aimed to a better understanding of the pathogenesis of psychiatric disorders, to more accurate prognosis and to better targeted therapeutic strategies.