Functional magnetic resonance imaging during auditory verbal working memory in nonpsychotic relatives of persons with schizophrenia: a pilot study

Investigating the association between symptoms and functional activity in brain regions in schizophrenia: A cross-sectional fmri-based neuroimaging study

Schizophrenia is a persistent neurological disorder profoundly affecting cognitive, emotional, and behavioral functions, prominently characterized by delusions, hallucinations, disordered speech, and abnormal motor activity. These symptoms often present diagnostic challenges due to their overlap with other forms of psychosis. Therefore, the implementation of automated diagnostic methodologies is imperative. This research leverages Functional Magnetic Resonance Imaging (fMRI), a neuroimaging modality capable of delineating functional activations across diverse brain regions. Furthermore, the utilization of evolving machine learning techniques for fMRI data analysis has significantly progressive. Here, our study stands as a novel attempt, focusing on the comprehensive assessment of both classical and atypical symptoms of schizophrenia. We aim to uncover associated changes in brain functional activity. Our study encompasses two distinct fMRI datasets (1.5T and 3T), each comprising 34 schizophrenia patients for the 1.5T dataset and 25 schizophrenia patients for the 3T dataset, along with an equal number of healthy controls. Machine learning algorithms are applied to assess data subsets, enabling an in-depth evaluation of the current functional condition concerning symptom impact. The identified voxels contribute to determining the brain regions most influenced by each symptom, as quantified by symptom intensity. This rigorous approach has yielded various new findings while maintaining an impressive classification accuracy rate of 97 %. By elucidating variations in activation patterns across multiple brain regions in individuals with schizophrenia, this study contributes to the understanding of functional brain changes associated with the disorder. The insights gained may inform differential clinical interventions and provide a means of assessing symptom severity accurately, offering new avenues for the management of schizophrenia.

Aberrant Cerebello-Thalamo-Cortical Functional and Effective Connectivity in First-Episode Schizophrenia With Auditory Verbal Hallucinations

The thalamus is known to be impaired in schizophrenia patients with auditory verbal hallucinations (AVHs). Abnormal filtering function of the thalamus has been found in schizophrenia patients with AVHs. However, a whole-structure approach has commonly been adopted when investigating thalamic dysconnectivity in patients with AVHs, and it remains unclear which thalamic nucleus is the critical structure underlying AVHs. Here, we investigated voxel-wise resting-state functional connectivity (rsFC) of the thalamic nucleus in drug-naïve patients with first-episode schizophrenia (FES) with AVHs. In addition, dynamic causal modeling was applied to compute effective connectivity and estimate causal relationships that could explain aberrant rsFC. Compared with the FES patients without AVH (NAVH) and normal controls, patients with AVHs had weaker rsFC of the bilateral medial pulvinar (PuM) nucleus-cerebellum. Moreover, compared with the normal control group, the AVH and NAVH groups had significantly stronger rsFC of the bilateral PuM nucleus-cerebral cortex, as well as weaker rsFC of the right medial geniculate nucleus-cerebral cortex. Compared with the NAVH and normal control groups, dynamic causal modeling revealed significantly stronger effective connectivity from the left PuM nucleus to the right inferior frontal gyrus in the AVH group. These findings indicate that the critical structure in the thalamus underlying AVHs is the PuM nucleus, and provide direct evidence that the cerebello-thalamo-cortical circuit is associated with AVHs.

The abiding relevance of mouse models of rare mutations to psychiatric neuroscience and therapeutics

Studies using powerful family-based designs aided by large scale case-control studies, have been instrumental in cracking the genetic complexity of the disease, identifying rare and highly penetrant risk mutations and providing a handle on experimentally tractable model systems. Mouse models of rare mutations, paired with analysis of homologous cognitive and sensory processing deficits and state-of-the-art neuroscience methods to manipulate and record neuronal activity have started providing unprecedented insights into pathogenic mechanisms and building the foundation of a new biological framework for understanding mental illness. A number of important principles are emerging, namely that degradation of the computational mechanisms underlying the ordered activity and plasticity of both local and long-range neuronal assemblies, the building blocks necessary for stable cognition and perception, might be the inevitable consequence and the common point of convergence of the vastly heterogeneous genetic liability, manifesting as defective internally- or stimulus-driven neuronal activation patterns and triggering the constellation of schizophrenia symptoms. Animal models of rare mutations have the unique potential to help us move from "which" (gene) to "how", "where" and "when" computational regimes of neural ensembles are affected. Linking these variables should improve our understanding of how symptoms emerge and how diagnostic boundaries are established at a circuit level. Eventually, a better understanding of pathophysiological trajectories at the level of neural circuitry in mice, aided by basic human experimental biology, should guide the development of new therapeutics targeting either altered circuitry itself or the underlying biological pathways.

Neurocognitive and Perceptual Processing in Genetic Mouse Models of Schizophrenia: Emerging Lessons

During the past two decades, the number of animal models of psychiatric disorders has grown exponentially. Of these, genetic animal models that are modeled after rare but highly penetrant mutations hold great promise for deciphering critical molecular, synaptic, and neurocircuitry deficits of major psychiatric disorders, such as schizophrenia. Animal models should aim to focus on core aspects rather than capture the entire human disease. In this context, animal models with strong etiological validity, where behavioral and neurophysiological phenotypes and the features of the disease being modeled are in unambiguous homology, are being used to dissect both elementary and complex cognitive and perceptual processing deficits present in psychiatric disorders at the level of neurocircuitry, shedding new light on critical disease mechanisms. Recent progress in neuroscience along with large-scale initiatives that propose a consistent approach in characterizing these deficits across different laboratories will further enhance the efficacy of these studies that will ultimately lead to identifying new biological targets for drug development.

Cognitive Phenotypes for Biomarker Identification in Mental Illness: Forward and Reverse Translation

Psychiatric illness has been acknowledged for as long as people were able to describe behavioral abnormalities in the general population. In modern times, these descriptions have been codified and continuously updated into manuals by which clinicians can diagnose patients. None of these diagnostic manuals have attempted to tie abnormalities to neural dysfunction however, nor do they necessitate the quantification of cognitive function despite common knowledge of its ties to functional outcome. In fact, in recent years the National Institute of Mental Health released a novel transdiagnostic classification, the Research Domain Criteria (RDoC), which utilizes quantifiable behavioral abnormalities linked to neurophysiological processes. This reclassification highlights the utility of RDoC constructs as potential cognitive biomarkers of disease state. In addition, with RDoC and cognitive biomarkers, the onus of researchers utilizing animal models no longer necessitates the recreation of an entire disease state, but distinct processes. Here, we describe the utilization of constructs from the RDoC initiative to forward animal research on these cognitive and behavioral processes, agnostic of disease. By linking neural processes to these constructs, identifying putative abnormalities in diseased patients, more targeted therapeutics can be developed.

Auditory Vigilance and Working Memory in Youth at Familial Risk for Schizophrenia or Affective Psychosis in the Harvard Adolescent Family High Risk Study

BACKGROUND

The degree of overlap between schizophrenia (SCZ) and affective psychosis (AFF) has been a recurring question since Kraepelin's subdivision of the major psychoses. Studying nonpsychotic relatives allows a comparison of disorder-associated phenotypes, without potential confounds that can obscure distinctive features of the disorder. Because attention and working memory have been proposed as potential endophenotypes for SCZ and AFF, we compared these cognitive features in individuals at familial high-risk (FHR) for the disorders.

METHODS

Young, unmedicated, first-degree relatives (ages, 13-25 years) at FHR-SCZ (n=41) and FHR-AFF (n=24) and community controls (CCs, n=54) were tested using attention and working memory versions of the Auditory Continuous Performance Test. To determine if schizotypal traits or current psychopathology accounted for cognitive deficits, we evaluated psychosis proneness using three Chapman Scales, Revised Physical Anhedonia, Perceptual Aberration, and Magical Ideation, and assessed psychopathology using the Hopkins Symptom Checklist -90 Revised.

RESULTS

Compared to controls, the FHR-AFF sample was significantly impaired in auditory vigilance, while the FHR-SCZ sample was significantly worse in working memory. Both FHR groups showed significantly higher levels of physical anhedonia and some psychopathological dimensions than controls. Adjusting for physical anhedonia, phobic anxiety, depression, psychoticism, and obsessive-compulsive symptoms eliminated the FHR-AFF vigilance effects but not the working memory deficits in FHR-SCZ.

CONCLUSIONS

The working memory deficit in FHR-SZ was the more robust of the cognitive impairments after accounting for psychopathological confounds and is supported as an endophenotype. Examination of larger samples of people at familial risk for different psychoses remains necessary to confirm these findings and to clarify the role of vigilance in FHR-AFF. (JINS, 2016, 22, 1026-1037).

Abnormal interactions of verbal- and spatial-memory networks in young people at familial high-risk for schizophrenia

BACKGROUND

Working memory impairment (especially in verbal and spatial domains) is the core neurocognitive impairment in schizophrenia and the familial high-risk (FHR) population. Inconsistent results have been reported in clinical and neuroimaging studies examining the verbal- and spatial-memory deficits in the FHR subjects, due to sample differences and lack of understanding on interactions of the brain regions for processing verbal- and spatial-working memory.

METHODS

Functional MRI data acquired during a verbal- vs. spatial-memory task were included from 51 young adults [26 FHR and 25 controls]. Group comparisons were conducted in brain activation patterns responding to 1) verbal-memory condition (A), 2) spatial-memory condition (B), 3) verbal higher than spatial (A-B), 4) spatial higher than verbal (B-A), 5) conjunction of brain regions that were activated during both A and B (A∧B). Group difference of the laterality index (LI) in inferior frontal lobe for condition A was also assessed.

RESULTS

Compared to controls, the FHR group exhibited significantly decreased brain activity in left inferior frontal during A, and significantly stronger involvement of ACC, PCC, paracentral gyrus for the contrast of A-B. The LI showed a trend of reduced left-higher-than-right pattern for verbal-memory processing in the HR group.

CONCLUSIONS

Our findings suggest that in the entire functional brain network for working-memory processing, verbal information processing associated brain pathways are significantly altered in people at familial high risk for developing schizophrenia. Future studies will need to examine whether these alterations may indicate vulnerability for predicting the onset of Schizophrenia.

Working Memory in Unaffected Relatives of Patients With Schizophrenia: A Meta-Analysis of Functional Magnetic Resonance Imaging Studies

Working memory deficits, a core cognitive feature of schizophrenia may arise from dysfunction in the frontal and parietal cortices. Numerous studies have also found abnormal neural activation during working memory tasks in patients' unaffected relatives. The aim of this study was to systematically identify and anatomically localize the evidence for those activation differences across all eligible studies. Fifteen functional magnetic resonance imaging (fMRI) manuscripts, containing 16 samples of 289 unaffected relatives of patients with schizophrenia, and 358 healthy controls were identified that met our inclusion criteria: (1) used a working memory task; and (2) reported standard space coordinates. Activation likelihood estimation (ALE) identified convergence across studies. Compared to healthy controls, patients' unaffected relatives showed decreases in neural activation in the right middle frontal gyrus (BA9), as well as right inferior frontal gyrus (BA44). Increased activation was seen in relatives in the right frontopolar (BA10), left inferior parietal lobe (BA40), and thalamus bilaterally. These results suggest that the familial risk of schizophrenia is expressed in changes in neural activation in the unaffected relatives in the cortical-subcortical working memory network that includes, but is not restricted to the middle prefrontal cortex.

Neural Correlates of Enhanced Genetic Risk for Schizophrenia

Schizophrenia is a disabling psychotic disorder characterized by hallucinations, delusions, and impaired functioning in many aspects of everyday life. The established condition generally becomes manifest in early adulthood, and evidence suggests that one of the most important risk factors for developing the disorder is inherited vulnerability. The established illness has been shown to be associated with deficits in many domains of cognitive function, along with structural and functional brain abnormalities, most notably in pre-frontal and temporal lobes. However, such studies have not been able to determine the extent to which such deficits relate to the presence of a schizophrenic predisposition, the presence of symptoms, and/or medication effects. A number of research groups have therefore turned to the study of relatives of affected individuals with the aim of determining if similar cognitive deficits and brain abnormalities are also found in those with increased genetic vulnerability to the disorder. In this article, studies on such individuals are discussed. It is concluded that deficits are apparent in relatives that are similar to but less marked than those seen in patients with schizophrenia.

Classifying individuals at high-risk for psychosis based on functional brain activity during working memory processing

The psychosis high-risk state is accompanied by alterations in functional brain activity during working memory processing. We used binary automatic pattern-classification to discriminate between the at-risk mental state (ARMS), first episode psychosis (FEP) and healthy controls (HCs) based on n-back WM-induced brain activity. Linear support vector machines and leave-one-out-cross-validation were applied to fMRI data of matched ARMS, FEP and HC (19 subjects/group).

The HC and ARMS were correctly classified, with an accuracy of 76.2% (sensitivity 89.5%, specificity 63.2%, p = 0.01) using a verbal working memory network mask. Only 50% and 47.4% of individuals were classified correctly for HC vs. FEP (p = 0.46) or ARMS vs. FEP (p = 0.62), respectively. Without mask, accuracy was 65.8% for HC vs. ARMS (p = 0.03) and 65.8% for HC vs. FEP (p = 0.0047), and 57.9% for ARMS vs. FEP (p = 0.18). Regions in the medial frontal, paracingulate, cingulate, inferior frontal and superior frontal gyri, inferior and superior parietal lobules, and precuneus were particularly important for group separation.

These results suggest that FEP and HC or FEP and ARMS cannot be accurately separated in small samples under these conditions. However, ARMS can be identified with very high sensitivity in comparison to HC. This might aid classification and help to predict transition in the ARMS.

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The ARMS was accurately identified based on an individual patient's response within a WM network.

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Regional cortical activations were particularly important for group separation.

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Based on WM alterations, FEP and HC or FEP and ARMS could not be accurately separated in small samples.

Cerebral Inefficient Activation in Schizophrenia Patients and Their Unaffected Parents during the N-Back Working Memory Task: A Family fMRI Study

Background

It has been suggested that working memory deficits is a core feature of symptomatology of schizophrenia, which can be detected in patients and their unaffected relatives. The impairment of working memory has been found related to the abnormal activity of human brain regions in many functional magnetic resonance imaging (fMRI) studies. This study investigated how brain region activation was altered in schizophrenia and how it was inherited independently from performance deficits.

Method

The authors used fMRI method during N-back task to assess working memory related cortical activation in four groups (N = 20 in each group, matching task performance, age, gender and education): schizophrenic patients, their unaffected biological parents, young healthy controls for the patients and older healthy controls for their parents.

Results

Compared to healthy controls, patients showed an exaggerated response in the right dorsolateral prefrontal cortex (brodmann area [BA] 46) and bilateral ventrolateral prefrontal cortex, and had reduced activation in bilateral dorsolateral prefrontal cortex (BA 9). In the conjunction analysis, the effect of genetic risk (parents versus older control) shared significantly overlapped activation with effect of disease (patients versus young control) in the right middle frontal gyrus (BA 46) and left inferior parietal gyrus (BA 40).

Conclusions

Physiological inefficiency of dorsal prefrontal cortex and compensation involvement of ventral prefrontal cortex in working memory function may one physiological characteristics of schizophrenia. And relatively inefficient activation in dorsolateral prefrontal cortex probably can be a promising intermediate phenotype for schizophrenia.

Working memory and default mode network abnormalities in unaffected siblings of schizophrenia patients

BACKGROUND

Impaired working memory (WM) is a hallmark of schizophrenia. In addition to classical WM regions such as the dorsolateral prefrontal cortex (DLPFC) and the striatum, dysfunctions in the default-mode network (DMN) contribute to these WM deficits. Unaffected siblings of patients also show WM impairments. However, the nature of the functional deficits underlying these impairments is unclear, mainly because of impaired performance confounding neuroimaging results.

METHODS

Here, we investigated WM and DMN activity in 23 unaffected siblings of schizophrenia patients and 24 healthy volunteers using fMRI and a Sternberg WM task. WM load was determined prior to scanning to ensure 90% accuracy for all subjects.

RESULTS

Siblings showed hyperactivation during the encoding phase of WM in the right medial prefrontal cortex (MPFC) which is the anterior part of the DMN. No differences were found during the maintenance phase. During the retrieval phase, siblings showed hyperactivation in WM regions: DLPFC, inferior parietal cortex and the striatum. Siblings who showed hyperactivity in the MPFC during encoding showed DLPFC and striatum hyperactivation during retrieval.

CONCLUSIONS

Our finding of hyperactivation in WM and DMN areas indicates that siblings fail to adequately inhibit DMN activity during demanding cognitive tasks and subsequently hyperactivate WM areas. This failure may reflect dopamine hyperactivity in the striatum which prevents adequate DMN suppression needed for effective WM. This study provides support for the notion that aberrant WM and DMN activation patterns may represent candidate endophenotypes for schizophrenia.

Assessment of cognition in non-affected full biological siblings of patients with schizophrenia

BACKGROUND

Schizophrenia is a devastating psychotic illness which is like the most mental disorders, shows complex inheritance; the transmission of the disorder most likely involves several genes and environmental factors. It is difficult to judge whether a particular person without schizophrenia has predisposing factors for the said disease. A few studies have shown the relative sensitivity and reliability of cognitive and psychophysiological markers of brain function as the susceptibility factors for schizophrenia which may aid us to find people with an increased risk of complex disorders like schizophrenia. The present work is an exploration on cognitive impairments in unaffected siblings of patients suffering from schizophrenia with a framework to explore why a mental disorder occurs in some families but not in others.

MATERIALS AND METHODS

This is a single point non-invasive study of non-affected full biological siblings of patients with schizophrenia, involving administration of a battery of neuropsychological tests to assess the cognitive function in the sibling group and a control group of volunteers with no history of psychiatric illness. The control group was matched for age, gender, and education. The siblings were also divided on the basis of the type of schizophrenia their siblings (index probands) were suffering from and their results compared with each other.

RESULTS

The siblings performed significantly poorly as compared to the controls on Wisconsin card sorting test (WCST), continuous performance test (CPT), and spatial working memory test (SWMT). The comparison between the sibling subgroups based on the type of schizophrenia in the index probands did not reveal any significant difference.

CONCLUSION

These findings suggest that there is a global impairment in the cognition of the non-affected siblings of patients of schizophrenia. Cognitive impairment might be one of the factors which will help us to hit upon people who are predisposed to develop schizophrenia in the future.

Altered cerebral response during cognitive control: a potential indicator of genetic liability for schizophrenia

Aberrant activity in brain regions underlying various aspects of executive cognition has been reported in patients with schizophrenia and in their healthy relatives, suggesting an association with genetic liability. The aim of this study was to investigate brain responses to selective aspects of cognitive control in unaffected siblings who are at increased genetic risk of schizophrenia. Altogether, 65 non-affected siblings, 70 patients with schizophrenia spectrum disorders, and 235 normal controls participated in this study. Blood-oxygen-level-dependent functional magnetic resonance imaging was conducted while participants performed a cognitive control task ('flanker task') to identify brain activity and connectivity associated with response inhibition and conflict monitoring, and suppression. Behaviorally, similar to patients with schizophrenia, siblings were less accurate when inhibiting prepotent responses relative to normal controls. During response inhibition, again similar to patients with schizophrenia, siblings showed decreased activity in the anterior cingulate (ACC), along with increased functional coupling with the dorsolateral prefrontal cortex (PFC) when compared to normal controls. Our findings show altered ACC activity and PFC connectivity in unaffected siblings and patients with schizophrenia during response inhibition. These results suggest that such changes in the neural activity underlying aspects of cognitive control may represent a potential intermediate phenotype for the investigation of the genetic basis of schizophrenia.

The application of nonlinear Dynamic Causal Modelling for fMRI in subjects at high genetic risk of schizophrenia

Nonlinear Dynamic Causal Modelling (DCM) for fMRI provides computational modelling of gating mechanisms at the neuronal population level. It allows for estimations of connection strengths with nonlinear modulation within task-dependent networks. This paper presents an application of nonlinear DCM in subjects at high familial risk of schizophrenia performing the Hayling Sentence Completion Task (HSCT). We analysed scans of 19 healthy controls and 46 subjects at high familial risk of schizophrenia, which included 26 high risk subjects without psychotic symptoms and 20 subjects with psychotic symptoms. The activity-dependent network consists of the intra parietal cortex (IPS), inferior frontal gyrus (IFG), middle temporal gyrus (MTG), anterior cingulate cortex (ACC) and the mediodorsal (MD) thalamus. The connections between the MD thalamus and the IFG were gated by the MD thalamus. We used DCM to investigate altered connection strength of these connections. Bayesian Model Selection (BMS) at the group and family level was used to compare the optimal bilinear and nonlinear models. Bayesian Model Averaging (BMA) was used to assess the connection strengths with the gating from the MD thalamus and the IFG. The nonlinear models provided the better explanation of the data. Furthermore, the BMA analysis showed significantly lower connection strength of the thalamocortical connection with nonlinear modulation from the MD thalamus in high risk subjects with psychotic symptoms and those who subsequently developed schizophrenia. These findings demonstrate that nonlinear DCM provides a method to investigate altered connectivity at the level of neural circuits. The reduced connection strength with thalamic gating may be a neurobiomarker implicated in the development of psychotic symptoms. This study suggests that nonlinear DCM could lead to new insights into functional and effective dysconnection at the network level in subjects at high familial risk.

Interaction between catechol-O-methyltransferase (COMT) Val158Met genotype and genetic vulnerability to schizophrenia during explicit processing of aversive facial stimuli

BACKGROUND

Emotion dysregulation is a key feature of schizophrenia, a brain disorder strongly associated with genetic risk and aberrant dopamine signalling. Dopamine is inactivated by catechol-O-methyltransferase (COMT), whose gene contains a functional polymorphism (COMT Val158Met) associated with differential activity of the enzyme and with brain physiology of emotion processing. The aim of the present study was to investigate whether genetic risk for schizophrenia and COMT Val158Met genotype interact on brain activity during implicit and explicit emotion processing.

METHOD

A total of 25 patients with schizophrenia, 23 healthy siblings of patients and 24 comparison subjects genotyped for COMT Val158Met underwent functional magnetic resonance imaging during implicit and explicit processing of facial stimuli with negative emotional valence.

RESULTS

We found a main effect of diagnosis in the right amygdala, with decreased activity in patients and siblings compared with control subjects. Furthermore, a genotype × diagnosis interaction was found in the left middle frontal gyrus, such that the effect of genetic risk for schizophrenia was evident in the context of the Val/Val genotype only, i.e. the phenotype of reduced activity was present especially in Val/Val patients and siblings. Finally, a complete inversion of the COMT effect between patients and healthy subjects was found in the left striatum during explicit processing.

CONCLUSIONS

Overall, these results suggest complex interactions between genetically determined dopamine signalling and risk for schizophrenia on brain activity in the prefrontal cortex during emotion processing. On the other hand, the effects in the striatum may represent state-related epiphenomena of the disorder itself.

Phase-specific brain change of spatial working memory processing in genetic and ultra-high risk groups of schizophrenia

Spatial working memory (WM) processing has 3 distinct phases: encoding, maintenance, and retrieval and its dysfunction is a core feature in schizophrenia. We examined phase-specific brain activations associated with spatial WM in first-degree relatives of schizophrenia (genetic high risk, GHR), ultra-high risk (UHR) subjects, patients with schizophrenia, and healthy controls. We used an event-related functional magnetic resonance imaging in 17 GHR subjects, 21 UHR subjects, 15 clinically stable patients with schizophrenia and 16 healthy controls, while subjects were performing a spatial delayed-response task. During the encoding phase, the GHR group showed increased activation in the fronto-parietal regions, whereas the UHR and schizophrenia groups showed significantly less activation in these regions than did the healthy control group. Especially, frontal activation was strongest in GHR subjects, followed by healthy controls, and occurred to a lesser degree in the UHR group, with the least activation occurring in the schizophrenia group. During the maintenance phase, the thalamus showed a differential activation, similar to frontal activation pattern during the encoding phase. During the retrieval phase, no prominent differential activations were found. Increased activations were observed in the superior temporal gyrus during the encoding and maintenance phases in the GHR, UHR, and schizophrenia groups relative to healthy controls. Our findings suggest that functional deficits associated with spatial WM processing emerge in the UHR before the onset of schizophrenia and compensatory neural processes exist in the GHR with genetic liability to schizophrenia.

Regional cortical thinning in subjects with high genetic loading for schizophrenia

OBJECTIVE

Although recent studies have revealed regional cortical thinning in patients with schizophrenia, it is not clear whether cortical thinning reflects a genetic liability for schizophrenia. The present study investigated the change of cortical thickness in subjects at genetic high risk (GHR) for schizophrenia with a relatively high genetic loading compared with healthy controls (HC) and patients with schizophrenia. The effect of genetic loading on cortical thinning was also measured by comparing GHR subgroups according to the levels of genetic loading.

METHODS

Cortical thickness was measured by the Constrained Laplacian-based Automated Segmentation with Proximities algorithm using 1.5-T structural MRI scans. The cortical thickness of the subjects at GHR (n=31) was compared with that of HC (n=29) and patients with schizophrenia (n=31). We then compared the cortical thickness of the GHR subgroups according to the number of first-degree relatives with schizophrenia to measure the effect of genetic loading.

RESULTS

Relative to HC, GHR subjects showed significant cortical thinning in the right anterior cingulate cortex (ACC), left paracingulate and posterior cingulate regions; bilateral frontal regions including frontal pole and ventromedial prefrontal cortex; bilateral temporal regions including the left parahippocampal gyrus; and bilateral inferior parietal and occipital regions; however, patients with schizophrenia showed more widespread cortical thinning in the fronto-temporo-parietal region. GHR subjects who had two or more first-degree relatives with schizophrenia showed a greater reduction in cortical thickness in the right ACC and in the left paracingulate cortex than did those who had only one first-degree relative with schizophrenia.

CONCLUSION

Our findings suggest that the level of genetic loading may have a dose-dependent effect on cortical thinning in the right ACC and in the left paracingulate cortex and that cortical thinning in GHR subjects may represent neurodevelopmental alterations that result from genetic liability for schizophrenia.

Auditory working memory impairments in individuals at familial high risk for schizophrenia

OBJECTIVES

The search for predictors of schizophrenia has accelerated with a growing focus on early intervention and prevention of psychotic illness. Studying nonpsychotic relatives of individuals with schizophrenia enables identification of markers of vulnerability for the illness independent of confounds associated with psychosis. The goal of these studies was to develop new auditory continuous performance tests (ACPTs) and evaluate their effects in individuals with schizophrenia and their relatives.

METHODS

We carried out two studies of auditory vigilance with tasks involving working memory (WM) and interference control with increasing levels of cognitive load to discern the information-processing vulnerabilities in a sample of schizophrenia patients, and two samples of nonpsychotic relatives of individuals with schizophrenia and controls. Study 1 assessed adults (mean age = 41), and Study 2 assessed teenagers and young adults age 13-25 (M = 19).

RESULTS

Patients with schizophrenia were impaired on all five versions of the ACPTs, whereas relatives were impaired only on WM tasks, particularly the two interference tasks that maximize cognitive load. Across all groups, the interference tasks were more difficult to perform than the other tasks. Schizophrenia patients performed worse than relatives, who performed worse than controls. For patients, the effect sizes were large (Cohen's d = 1.5), whereas for relatives they were moderate (d = ~0.40-0.50). There was no age by group interaction in the relatives-control comparison except for participants <31 years of age.

CONCLUSIONS

Novel WM tasks that manipulate cognitive load and interference control index an important component of the vulnerability to schizophrenia.

Event-related potentials and changes of brain rhythm oscillations during working memory activation in patients with first-episode psychosis

BACKGROUND

Earlier contributions have documented significant changes in sensory, attention-related endogenous event-related potential (ERP) components and θ band oscillatory responses during working memory activation in patients with schizophrenia. In patients with first-episode psychosis, such studies are still scarce and mostly focused on auditory sensory processing. The present study aimed to explore whether subtle deficits of cortical activation are present in these patients before the decline of working memory performance.

METHODS

We assessed exogenous and endogenous ERPs and frontal θ event-related synchronization (ERS) in patients with first-episode psychosis and healthy controls who successfully performed an adapted 2-back working memory task, including 2 visual n-backworking memory tasks as well as oddball detection and passive fixation tasks.

RESULTS

We included 15 patients with first-episode psychosis and 18 controls in this study. Compared with controls, patients with first-episode psychosis displayed increased latencies of early visual ERPs and phasic θ ERS culmination peak in all conditions. However, they also showed a rapid recruitment of working memory-related neural generators, even in pure attention tasks, as indicated by the decreased N200 latency and increased amplitude of sustained θ ERS in detection compared with controls.

LIMITATIONS

Owing to the limited sample size, no distinction was made between patients with first-episode psychosis with positive and negative symptoms. Although we controlled for the global load of neuroleptics, medication effect cannot be totally ruled out.

CONCLUSION

The present findings support the concept of a blunted electroencephalographic response in patients with first-episode psychosis who recruit the maximum neural generators in simple attention conditions without being able to modulate their brain activation with increased complexity of working memory tasks.

The influence of emotional distraction on verbal working memory: an fMRI investigation comparing individuals with schizophrenia and healthy adults

The ability to maintain information over short periods of time (i.e., working memory) is critically important in a variety of cognitive functions including language, planning, and decision-making. Recent functional Magnetic Resonance Imaging (fMRI) research with healthy adults has shown that brain activations evoked during the delay interval of working memory tasks can be reduced by the presentation of distracting emotional events, suggesting that emotional events may take working-memory processes momentarily offline. Both executive function and emotional processing are disrupted in schizophrenia, and here we sought to elucidate the effect of emotional distraction upon brain activity in schizophrenic and healthy adults performing a verbal working memory task. During the delay period between the memoranda and memory probe items, emotional and neutral distractors differentially influenced brain activity in these groups. In healthy adults, the hemodynamic response from posterior cingulate, orbital frontal cortex, and the parietal lobe strongly differentiated emotional from neutral distractors. In striking contrast, schizophrenic adults showed no significant differences in brain activation when processing emotional and neutral distractors. Moreover, the influence of emotional distractors extended into the memory probe period in healthy, but not schizophrenic, adults. The results suggest that although emotional items are highly salient for healthy adults, emotional items are no more distracting than neutral ones to individuals with schizophrenia.

Sustained attention and working memory deficits follow a familial pattern in schizophrenia

Cognitive deficits are core features of schizophrenia and considered putative endophenotypes. This study assessed the familial pattern of deficits in sustained attention, working memory and executive function in remitted-schizophrenia patients and their unaffected siblings. Sixteen patients, 16 unaffected siblings, and 17 healthy control subjects underwent a battery of neuropsychological tasks that have so far yielded mixed findings in performance differences. Both groups had prolonged reaction times compared with controls in sustained attention tasks; the siblings made more false alarms in the working memory task, but only the patients' performance was poorer in the executive function tasks. These findings further support sustained attention and working memory deficits as potential endophenotypes of schizophrenia. Reaction time and false alarm rates are suggested as additional useful endophenotypic measures that could potentially account for differences in performance in tasks that are not purported to examine the specific measures per se.

Exaggerated brain activation during emotion processing in unaffected siblings of patients with schizophrenia

BACKGROUND

Schizophrenia is characterized by impaired social cognition, including emotion processing. Behavioral studies have reported impaired performance on various emotion processing tasks, and imaging studies in patients have observed aberrant activity within the underlying neural circuitry. Also, subjects at increased genetic risk of developing schizophrenia, including unaffected siblings of patients, show behavioral impairments in emotion processing. It is unclear, however, whether and how the underlying neural system is disrupted in these subjects. In this study, we investigated whether siblings of patients with schizophrenia show abnormal brain activation during basic emotion processing.

METHODS

Brain activity was measured using functional magnetic resonance imaging in 24 unaffected siblings of patients with schizophrenia and 25 healthy control subjects while they viewed and rated neutral, positive, and negative pictures. None of the subjects had a psychiatric disorder, and the two groups did not differ in age, gender, or level of own, paternal, or maternal education.

RESULTS

Compared with control subjects, siblings showed increased activity within the amygdala, hippocampus, medial prefrontal cortex, posterior and anterior cingulate cortex, and middle temporal gyrus in response to emotionally arousing pictures relative to neutral pictures. No activation differences between the groups were found during the neutral stimuli, indicating that the observed hyperactivity is likely caused by abnormal emotion processing rather than impaired visuoattentional processing.

CONCLUSIONS

Our findings of hyperactivity in siblings during emotion processing suggest that functional abnormalities within the neural circuitry of emotion processing are related to the genetic risk for developing schizophrenia.

Executive functioning-related brain abnormalities associated with the genetic liability for schizophrenia: an activation likelihood estimation meta-analysis

BACKGROUND

Relatives of schizophrenia patients demonstrate abnormalities in prefrontal cortical activation during executive processing as measured by functional neuroimaging, albeit not consistently. A meta-analysis was conducted to determine whether reliable patterns of brain hypo- and hyperactivity, especially in the middle frontal region, were present in the relatives of patients.

METHOD

Seventeen studies, containing 18 samples of relatives and controls, were included in this meta-analysis. Studies were included if relatives of schizophrenia patients were compared to controls, an executive processing task was used, and standard space coordinates were reported for the functional activations. Activation likelihood estimation (ALE) was implemented to find convergence across functional neuroimaging experiment coordinates. A separate analysis was conducted to assess the potential impact of a priori hypothesis testing used in region-of-interest (ROI) approaches on the meta-analysis results.

RESULTS

Relatives demonstrated hypo- and hyperactivity in statistically overlapping right middle frontal regions [Brodmann area (BA) 9/10]. Use of an ROI analysis that a priori focused on prefrontal regions resulted in more findings of reduced activity in the middle frontal region.

CONCLUSIONS

The cortical regions identified by this meta-analysis could potentially serve as intermediate biological markers in the search for candidate genes for schizophrenia. As neurocognitive deficits are related to functional impairments in patients, a better understanding of neural and genetic vulnerabilities would be beneficial in our efforts to remediate these important deficits.

Cognitive control deficits in schizophrenia: mechanisms and meaning

Although schizophrenia is an illness that has been historically characterized by the presence of positive symptomatology, decades of research highlight the importance of cognitive deficits in this disorder. This review proposes that the theoretical model of cognitive control, which is based on contemporary cognitive neuroscience, provides a unifying theory for the cognitive and neural abnormalities underlying higher cognitive dysfunction in schizophrenia. To support this model, we outline converging evidence from multiple modalities (eg, structural and functional neuroimaging, pharmacological data, and animal models) and samples (eg, clinical high risk, genetic high risk, first episode, and chronic subjects) to emphasize how dysfunction in cognitive control mechanisms supported by the prefrontal cortex contribute to the pathophysiology of higher cognitive deficits in schizophrenia. Our model provides a theoretical link between cellular abnormalities (eg, reductions in dentritic spines, interneuronal dysfunction), functional disturbances in local circuit function (eg, gamma abnormalities), altered inter-regional cortical connectivity, a range of higher cognitive deficits, and symptom presentation (eg, disorganization) in the disorder. Finally, we discuss recent advances in the neuropharmacology of cognition and how they can inform a targeted approach to the development of effective therapies for this disabling aspect of schizophrenia.

Effects of the BDNF val66met polymorphism on prefrontal brain function in a population at high genetic risk of schizophrenia

A single nucleotide polymorphism (val66met) in the brain derived neurotrophic factor (BDNF) gene has been shown to be a risk factor for a number of psychiatric disorders, including schizophrenia. This polymorphism has also been shown to have effects on prefrontal brain morphology and function. This study aims to clarify the effects of the val66met polymorphism on prefrontal brain function in a population at high genetic risk for schizophrenia. The Edinburgh High Risk Study has followed young individuals who had one first- or second-degree relative with schizophrenia and a minimum of one further genetic relative with the illness. A sample of 62 individuals provided both genetic and functional imaging data using the Hayling sentence completion task. Individuals with the BDNF ValVal (presumed risk) genotype (n = 41) showed relatively increased activation of the anterior cingulate cortex in relation to Met carrier individuals (n = 21) during sentence completion conditions versus baseline, against a background of similar levels of task performance. It appeared from further investigation that this relatively increased activation was attributable to a failure to disengage or suppress activation in the high risk ValVal group during the task condition, suggesting that BDNF may contribute to the abnormal default network reported in schizophrenia. These results suggest that this gene affects prefrontal brain function in those at high genetic risk for the disorder, unconfounded by medication effects. BDNF may therefore be one of the heritable factors involved in the development of abnormal prefrontal function in schizophrenia. © 2010 Wiley-Liss, Inc.

Qualifying brain functional MRI parameters as endophenotypes in schizophrenia

Although the genetic contribution to schizophrenia pathogenesis has been well established, with an approximate heritability of 81%, the endeavor to elucidate the complex genetic architecture of schizophrenia has met limited success. ‘Endophenotypes’, or ‘intermediate phenotypes’, are more restricted constructs of genetic risk than the clinical manifestations hitherto employed by molecular geneticists. They are, putatively, intermediate in the pathophysiological pathway between genetic variation and clinical phenomenology and can possibly be used to assist in the elucidation of genetic diathesis for schizophrenia. In this article, we present the current evidence that supports functional MRI parameters as promising candidate endophenotypes in schizophrenia.

Rethinking the genetic basis for comorbidity of schizophrenia and type 2 diabetes

The co-occurrence of schizophrenia (SCZ) and type 2 diabetes mellitus (T2D) has been well documented. This review article focuses on the hypothesis that the co-occurrence of SCZ and T2D may be, at least in part, driven by shared genetic factors. Previous genetic studies of T2D and SCZ evidence have disclosed a number of overlapped risk loci. However, the putative common genetic factors for SCZ and T2D remain inconclusive due to inconsistent findings. A systemic review of methods of identifying genetic loci contributing to the comorbidity link between SCZ and T2D is hence needed. In the current review article, we have discussed several different approaches to localizing the shared susceptibility genes for these two diseases. To begin with, one could start with probing the gene involved in both glucose and dopamine metabolisms. Additionally, hypothesis-free genome-wide association studies (GWAS) may provide more clues to the common genetic basis for these two diseases. Genetic similarities inferred from GWAS may shed some light on the genetic mechanism underlying the comorbidity link between SCZ and T2D. Meanwhile, endophenotypes (e.g., adiponectin level in T2D and working memory in SCZ) may serve as alternative phenotypes that are more directly influenced by genes than target diseases. Hence, endophenotypes of these diseases may be more tractable to identification. To summarize, novel approaches are needed to dissect the complex genetic basis of the comorbidity of SCZ and T2D.

Impact of schizophrenia-risk gene dysbindin 1 on brain activation in bilateral middle frontal gyrus during a working memory task in healthy individuals

Working memory (WM) dysfunction is a hallmark feature of schizophrenia. Functional imaging studies using WM tasks have documented both prefrontal hypo- and hyperactivation in schizophrenia. Schizophrenia is highly heritable, and it is unclear which susceptibility genes modulate WM and its neural correlates. A strong linkage between genetic variants in the dysbindin 1 gene and schizophrenia has been demonstrated. The aim of this study was to investigate the influence of the DTNBP1 schizophrenia susceptibility gene on WM and its neural correlates in healthy individuals. Fifty-seven right-handed, healthy male volunteers genotyped for DTNBP1 SNP rs1018381 status were divided in heterozygous risk-allele carriers (T/C) and homozygous noncarriers (C/C). WM was assessed by a 2-back vs. 0-back version of the Continuous Performance Test (CPT), while brain activation was measured with fMRI. DTNBP1 SNP rs1018381 carrier status was determined and correlated with WM performance and brain activation. Despite any differences in behavioral performance, risk-allele carriers exhibited significantly increased activation of the bilateral middle frontal gyrus (BA 9), a part of the dorsolateral prefrontal cortex (DLPFC), compared to noncarriers. This difference did not correlate with WM performance. The fMRI data provide evidence for an influence of genetic variation in DTNBP1 gene region tagged by SNP rs1018381 on bilateral middle frontal gyrus activation during a WM task. The increased activation in these brain areas may be a consequence of "inefficient" or compensatory DLPFC cognitive control functions.

Thalamic pathology in schizophrenia

The thalamus plays a critical role in the coordination of information as it passes from region to region within the brain. A disruption of that information flow may give rise to some of the cardinal symptoms of schizophrenia. In support of this hypothesis, schizophrenia-like syndromes emerge when illnesses, such as stroke, selectively damage the thalamus while sparing the rest of the brain. Evidence from many sources has implicated thalamic dysfunction in schizophrenia. In postmortem studies, several subregions of the thalamus, including the mediodorsal nucleus and the pulvinar, have been shown to have fewer neurons in schizophrenia. Neurochemical disturbances are also seen, with changes in both the glutamate and dopamine systems; thalamic glutamate receptor expression is altered in schizophrenia, and dopamine appears to be elevated in thalamic subregions, while evidence exists of an imbalance between dopamine and other neurotransmitters. In vivo studies using magnetic resonance imaging have demonstrated smaller thalamic volumes in schizophrenia, as well as shape deformations suggesting changes in those thalamic regions that are most densely connected to the portions of the brain responsible for executive function and sensory integration. These changes seem to be correlated with clinical symptoms. The thalamus is a starting point for several parallel, overlapping networks that extend from thalamic nuclei to the cortex. Evidence is emerging that changes in the thalamic nodes of these networks are echoed by changes at other points along the chain; this suggests that schizophrenia might be a disease of disrupted thalamocortical neural networks. This model distributes the pathology throughout the network, but also concentrates attention on the thalamus as a critical structure, especially because of its role in coordinating the flow of information within and between neural networks.

Efficiency of working memory encoding in twins discordant for schizophrenia

It has been proposed that patients with schizophrenia and some of their relatives suffer from reduced neurocognitive efficiency, increasing their sensitivity to experimental task demands. The present study evaluated such a possibility during performance of a working memory task by schizophrenia patients and their co-twins along with a healthy control sample. Electrophysiological data were obtained from sets of nine twin pairs (monozygotic and dizygotic pairs collapsed) discordant for a diagnosis of schizophrenia and from nine matched healthy control twin pairs, during administration of a variable-load spatial working memory task. Event-related potentials (ERPs) were measured immediately after memory set onset and during a delay period. For correctly performed trials, slow-wave ERP activity measured during the late stimulus encoding and delay periods exhibited a significant Diagnostic Group-by-Memory Load interaction, with schizophrenia patients showing a differentially strong load effect. Patients' co-twins displayed an intermediate level of load sensitivity while healthy controls showed no significant load effect. These results support an inefficiency model of neurocognitive dysfunction in schizophrenia, a pattern that appears to be related to the pathogenesis and inheritance of the disorder. Furthermore, this inefficiency appeared during the late stimulus encoding stage of working memory functioning, possibly reflecting disruptions in stimulus representation consolidation.

Convergent approaches for defining functional imaging endophenotypes in schizophrenia

In complex genetic disorders such as schizophrenia, endophenotypes have potential utility both in identifying risk genes and in illuminating pathophysiology. This is due to their presumed status as closer in the etiopathological pathway to the causative genes than is the currently defining clinical phenomenology of the illness and thus their simpler genetic architecture than that of the full syndrome. There, many genes conferring slight individual risk are additive or epistatic (interactive) with regard to cumulative schizophrenia risk. In addition the use of endophenotypes has encouraged a conceptual shift away from the exclusive study of categorical diagnoses in manifestly ill patients, towards the study of quantitative traits in patients, unaffected relatives and healthy controls. A more recently employed strategy is thus to study unaffected first-degree relatives of schizophrenia patients, who share some of the genetic diathesis without illness-related confounds that may themselves impact fMRI task performance. Consistent with the multiple biological abnormalities associated with the disorder, many candidate endophenotypes have been advanced for schizophrenia, including measures derived from structural brain imaging, EEG, sensorimotor integration, eye movements and cognitive performance (Allen et al., 2009), but recent data derived from quantitative functional brain imaging measures present additional attractive putative endophenotypes. We will review two major, conceptually different approaches that use fMRI in this context. One, the dominant paradigm, employs defined cognitive tasks on which schizophrenia patients perform poorly as "cognitive stress tests". The second uses very simple probes or "task-free" approaches where performance in patients and controls is equal. We explore the potential advantages and disadvantages of each method, the associated data analytic approaches and recent studies exploring their interface with the genetic risk architecture of schizophrenia.

Imaging genetic liability to schizophrenia: systematic review of FMRI studies of patients' nonpsychotic relatives

There is a growing literature on brain activity in the nonpsychotic first-degree relatives of patients with schizophrenia as measured using functional imaging. This systematic review examined 20 studies in 4 domains of cognition, including cognitive control (7 samples), working memory (5 samples), long-term memory (4 samples), and language (4 samples). While the literature was widely divergent, these studies did consistently find activation differences between patients' relatives and controls. The most consistent increases in activation within hemisphere were found in right ventral prefrontal cortex (PFC) and right parietal cortex. Abnormal activity, defined as significant increases or decreases in activation relative to controls irrespective of hemisphere, was found in about two-thirds of contrasts in the cerebellum, dorsal prefrontal, lateral temporal, and parietal cortices, and thalamus, with basal ganglia and ventral PFC showing abnormalities in approximately half of those contrasts. Anterior cingulate was generally spared in patients' relatives. The diversity of findings in studies of patients' relatives may derive from differences between the cognitive demands across studies. We identify avenues for building a more accurate and cumulative literature, including symmetrical inclusion criteria for relatives and controls, recording in-scanner responses, using both a priori and whole-brain tests, explicitly reporting threshold values, reporting main effects of task, reporting effect sizes, and quantifying the risk of false negatives. While functional imaging in the relatives of schizophrenia patients remains a promising methodology for understanding the impact of the unexpressed genetic liability to schizophrenia, no single region or mechanism of abnormalities has yet emerged.

Inefficient neural activity in patients with schizophrenia and nonpsychotic relatives of schizophrenic patients: evidence from a working memory task

Studies of schizophrenia with functional MRI have shown hyper- and hypoactivations in various brain regions including the prefrontal cortex. Functional anomalies have also been reported in first-degree relatives of schizophrenic patients. The aim of this study was to examine working memory related brain functions in healthy subjects, schizophrenic patients and unaffected relatives and to determine the influence of psychopathology on these processes. A parametric n-back working memory task and functional MRI were used to examine 61 patients with schizophrenia, 11 nonpsychotic relatives of schizophrenic patients and a comparison group of 61 healthy subjects. The results indicated increased as well as decreased brain functions in schizophrenic patients compared to the control group depending on the task difficulty and the performance: during the attention task (0-back), which served as control condition, behavioral responses of patients and healthy subjects hardly differed but BOLD responses were considerably enhanced in schizophrenic patients. With increasing task difficulty differences between groups in BOLD responses diminished whereas behavioral deficits of patients increased. The examination of attention-independent working memory-functions (2- vs. 0-back) produced hypoactivations in patients, especially in frontal, temporal and subcortical brain regions. Furthermore, positive symptoms were associated with parietal dysfunctions. Behavioral performance and neural responses of unaffected relatives of schizophrenic patients were intermediate between schizophrenic patients and controls indicating slight brain dysfunctions. In addition, compensatory strategies were demonstrated. These findings suggest that the genetic risk for schizophrenia is accompanied by neural inefficiency which is associated with cognitive deficits, especially in difficult tasks.

Brain activation during executive processes in schizophrenia

Schizophrenia patients show some deficits in executive processes (impaired behavioural performance and abnormal brain functioning). The aim of this study is to explore the brain activity of schizophrenia patients during different inhibitory tasks. We used functional magnetic resonance imaging to investigate to investigate the restraint and deletion aspects of inhibition in 19 patients with schizophrenia and 12 normal subjects during the performance of the Hayling and the N-back tasks. The patients demonstrated impaired performance (more errors and longer reaction times) in the Hayling task. Schizophrenia subjects activated the same fronto-parietal network as the control subjects but demonstrated stronger parietal activations. For the N-back task, the deficit shown by the patients was limited to the number of target omissions. The reaction times and the number of false alarms did not differ in the two groups. We interpret this pattern of deficit as an alteration of working memory processes (and unaltered inhibition). Schizophrenia subjects showed higher activations in a fronto-parietal network. Since schizophrenia patients reached normal inhibitory performances in the N-back task and not in the Hayling task, the frontal hyperactivation may reflect an increased effort or a compensatory mechanism that facilitates the performance of executive tasks. During the Hayling task, this frontal hyperactivation was not achieved, and its absence was associated with a performance deficit relative to the performance of normal subjects.

Structural and functional brain correlates of subclinical psychotic symptoms in 11-13 year old schoolchildren

Studying children experiencing psychotic symptoms provides a unique opportunity to examine the vulnerability to psychosis within the context of development. Using neuroimaging techniques this study investigated cognitive control functions, brain volumetrics and white matter integrity in an at-risk cohort of children. Between-subjects assessment of brain function and structure among 11 school-going, non-treatment seeking children aged 11-13 who were at symptomatic risk for psychosis (AR) and 14 healthy control children aged 11-12 without subclinical psychotic symptoms (CON). MRI assessments included functional measures of response inhibition and error-related processes, whole brain voxel-based morphometry (VBM) of gray matter (GM) and diffusion tensor imaging (DTI) utilizing fractional anisotropy to probe white matter (WM) integrity. fMRI results showed reduced activity in the AR group within right frontal and bilateral temporal cortex for response inhibition and reduced activity within the anterior cingulate, insula and middle frontal gyrus for error-related processing (p<.05, corrected). VBM analysis revealed GM increases in the AR group within middle and superior temporal gyri, angular gyrus, orbitofrontal gyrus and GM decrease within the inferior temporal gyrus (p<.05, corrected). DTI analysis identified WM decreases in the AR group along the inferior fronto-occipital fasciculus, cingulum and inferior longitudinal fasciculus (p<.05, corrected). This multimodal investigation revealed aberrant prefrontal-temporal dysfunction in addition to cingulate and insular dysfunctions which provide potential early neurocognitive risk markers related to the susceptibility for developing psychosis and subsequently the neurodevelopmental trajectory leading to schizophrenia.

Neuregulin 1 ICE-single nucleotide polymorphism in first episode schizophrenia correlates with cerebral activation in fronto-temporal areas

The Neuregulin (NRG1) gene has been associated with schizophrenia, but its functional implications are largely unknown. Our aim was to assess differential brain activation between patients carrying an at-risk allele on the Neuregulin 1 gene and patients without this genetic risk. Neural signal changes between 14 first episode schizophrenia patients with the at risk allele (SNP8NRG221533) from the Icelandic core haplotype and 14 without were measured with fMRI during a working memory task. Patients without the at risk allele showed greater activations (P < 0.05; corrected) in the left hippocampus, precuneus and cerebellum, as well as the right anterior cingulate. Brain regions previously associated with the pathology of Schizophrenia are differentially affected in those with a genetic at risk status in the NRG1 gene. Heterogeneity of structural and functional measures within patients characterized by clinical phenotypes may be in part due to this genetic variation.

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.

FMRI indices of auditory attention in schizophrenia

The present study sought to identify abnormalities in activation in several brain regions in response to an auditory attention task in patients with schizophrenia. Ten patients and twenty healthy control participants were examined using Functional Magnetic Resonance Imaging (FMRI) measures acquired during an auditory attention task. Region of interest analyses of activation of targeted regions implicated in attention included: anterior cingulate cortex (ACC), dorsolateral prefrontal cortex (DLPFC), hippocampus, parahippocampal gyrus (PHG), and superior temporal gyrus (STG). The results indicated over-activation in patients with schizophrenia. While the control group showed notable coherence in activation within and across hemispheres the schizophrenia group showed relatively less coherence overall that was only present in the right hemisphere. These findings suggest that patients with schizophrenia show both an over-engagement of brain regions during attention task as well as a lack of communication among neural regions involved.

CNTRICS final task selection: working memory

The third meeting of the Cognitive Neuroscience Treatment Research to Improve Cognition in Schizophrenia (CNTRICS) was focused on selecting promising measures for each of the cognitive constructs selected in the first CNTRICS meeting. In the domain of working memory, the 2 constructs of interest were goal maintenance and interference control. CNTRICS received 3 task nominations for each of these constructs, and the breakout group for working memory evaluated the degree to which each of these tasks met prespecified criteria. For goal maintenance, the breakout group for working memory recommended the AX-Continuous Performance Task/Dot Pattern Expectancy task for translation for use in clinical trial contexts in schizophrenia research. For interference control, the breakout group recommended the recent probes and operation/symmetry span tasks for translation for use in clinical trials. This article describes the ways in which each of these tasks met the criteria used by the breakout group to recommend tasks for further development.

Cortical thickness abnormalities in cocaine addiction--a reflection of both drug use and a pre-existing disposition to drug abuse?

The structural effects of cocaine on neural systems mediating cognition and motivation are not well known. By comparing the thickness of neocortical and paralimbic brain regions between cocaine-dependent and matched control subjects, we found that four of 18 a priori regions involved with executive regulation of reward and attention were significantly thinner in addicts. Correlations were significant between thinner prefrontal cortex and reduced keypresses during judgment and decision making of relative preference in addicts, suggesting one basis for restricted behavioral repertoires in drug dependence. Reduced effortful attention performance in addicts also correlated with thinner paralimbic cortices. Some thickness differences in addicts were correlated with cocaine use independent of nicotine and alcohol, but addicts also showed diminished thickness heterogeneity and altered hemispheric thickness asymmetry. These observations suggest that brain structure abnormalities in addicts are related in part to drug use and in part to predisposition toward addiction.

Functional magnetic resonance imaging (fMRI) of attention processes in presumed obligate carriers of schizophrenia: preliminary findings

BACKGROUND

Presumed obligate carriers (POCs) are the first-degree relatives of people with schizophrenia who, although do not exhibit the disorder, are in direct lineage of it. Thus, this subpopulation of first-degree relatives could provide very important information with regard to the investigation of endophenotypes for schizophrenia that could clarify the often contradictory findings in schizophrenia high-risk populations. To date, despite the extant literature on schizophrenia endophenotypes, we are only aware of one other study that examined the neural mechanisms that underlie cognitive abnormalities in this group. The aim of this study was to investigate whether a more homogeneous group of relatives, such as POCs, have neural abnormalities that may be related to schizophrenia.

METHODS

We used functional magnetic resonance imaging (fMRI) to collect blood oxygenated level dependent (BOLD) response data in six POCs and eight unrelated healthy controls while performing under conditions of sustained, selective and divided attention.

RESULTS

The POCs indicated alterations in a widely distributed network of regions involved in attention processes, such as the prefrontal and temporal (including the parahippocampal gyrus) cortices, in addition to the anterior cingulate gyrus. More specifically, a general reduction in BOLD response was found in these areas compared to the healthy participants during attention processes.

CONCLUSION

These preliminary findings of decreased activity in POCs indicate that this more homogeneous population of unaffected relatives share similar neural abnormalities with people with schizophrenia, suggesting that reduced BOLD activity in the attention network may be an intermediate marker for schizophrenia.

Prefrontal dysfunction in first-degree relatives of schizophrenia patients during a Stroop task

Schizophrenia patients perform poorly on cognitive control tasks and exhibit dysfunction in anterior cingulate cortex (ACC) and dorsolateral prefrontal cortex (DLPFC) during task performance. The unaffected relatives of patients with schizophrenia also exhibit poor cognitive control task performance. However, the relationship between these behavioral deficits in relatives and the integrity of ACC and DLPFC functioning is unclear. In the present study, we used the Stroop color-naming task and event-related fMRI to examine cognitive control task performance and associated neural activity in 17 unaffected relatives of schizophrenia patients and 17 demographically matched healthy controls. On the Stroop task, unaffected relatives exhibited intact post-conflict-related performance adjustments. fMRI data revealed that unaffected relatives exhibited reduced activity in DLPFC but they exhibited intact activity in ACC. These results suggest that DLPFC dysfunction may be related to the genetic risk for schizophrenia as both patients and their unaffected relatives show reduced activity in this region. In contrast, the current results suggest that ACC dysfunction in people with schizophrenia may reflect processes specific to the illness itself.

An fMRI study of working memory in first-degree unaffected relatives of schizophrenia patients

Identifying intermediate phenotypes of genetically complex psychiatric illnesses such as schizophrenia is important. First-degree relatives of persons with schizophrenia have increased genetic risk for the disorder and tend to show deficits on working memory (WM) tasks. An open question is the relationship between such behavioral endophenotypes and the corresponding brain activation patterns revealed during functional imaging. We measured task performance during a Sternberg WM task and used functional magnetic resonance imaging (fMRI) to assess whether 23 non-affected first-degree relatives showed altered performance and functional activation compared to 43 matched healthy controls. We predicted that a significant proportion of unaffected first-degree relatives would show either aberrant task performance and/or abnormal related fMRI blood oxygen level dependent (BOLD) patterns. While task performance in the relatives was not different than that of controls they were significantly slower in responding to probes., Schizophrenia relatives displayed reduced activation, most markedly in bilateral dorsolateral/ventrolateral (DLPFC/VLPFC) prefrontal and posterior parietal cortex when encoding stimuli and in bilateral DLPFC and parietal areas during response selection. Additionally, fMRI differences in both conditions were modulated by load, with a parametric increase in between-group differences with load in several key regions during encoding and an opposite effect during response selection.

Genetic variation in the DAOA (G72) gene modulates hippocampal function in subjects at high risk of schizophrenia

BACKGROUND

Strong evidence exists for an association between genetic variation in the gene DAOA (D-amino acid oxidase activator, also known as G72) and risk for schizophrenia. Preliminary evidence in healthy control subjects has implicated genetic variation in the DAOA gene in the modulation of hippocampal complex and prefrontal cortex activation.

METHODS

Assessment was performed on 61 subjects at high genetic risk of schizophrenia for familial reasons. All subjects were genotyped for two closely linked single nucleotide polymorphisms in the DAOA gene complex, M23 (rs3918342) and M24 (rs1421292), that have previously shown association with schizophrenia. The effect of genotype on brain activation was assessed with functional magnetic resonance imaging data gathered during performance of the verbal initiation section of the Hayling Sentence Completion Task.

RESULTS

Differences between DAOA genotype groups were seen in the activation of the left hippocampus and parahippocampus in the contrast of sentence completion versus rest. In addition the DAOA genotype groups differed in their recruitment of right inferior prefrontal cortex in relation to increasing task difficulty. The effects of genotype on brain activation could not be explained in terms of differences in grey matter density.

CONCLUSIONS

These results support the view that genetic variation in the DAOA gene influences hippocampal complex and prefrontal cortex function, an effect that might be particularly prominent in the context of enhanced genetic risk for schizophrenia.

Emotion processing in persons at risk for schizophrenia

Evidence suggests that individuals with schizophrenia demonstrate emotion-processing deficits. However, the nature and extent of emotion abnormalities in individuals considered at risk for schizophrenia have not been previously summarized. This article provides a review of the recent literature pertaining to emotion processing in 3 at-risk populations: those at familial high risk, those with schizotypal characteristics, and those in the putative prodrome to psychosis. Studies are reviewed across the components of emotion perception, experience, and expression. Further, we discuss investigations into psychophysiology, brain structure, and brain function that employ emotion probes. Review of the literature suggests that individuals at high risk demonstrate similar abnormalities to those with schizophrenia but at an attenuated level. The most robust findings in at-risk groups are in the areas of reduced emotion perception, self-reported anhedonia, and increased negative affect. We conclude with an agenda for future research.

Genetic influences on hippocampal structure and function in recombinant inbred mice

Previously, we identified separate genetic influences on ventral versus dorsal hippocampal volume in BXD recombinant inbred mice [Martin MV, Dong HX, Vallera D, Lu L, Williams RW, Rosen GD, et al. Independent quantitative trait loci influence ventral and dorsal hippocampal volume in recombinant inbred strains of mice. Genes Brain Behav 2006;5:614-23]. Based on genotype at genetic markers associated with ventral hippocampal volume, we evaluated BXD mouse strains with relatively small versus large ventral hippocampal volumes using numerous behavioral paradigms known to rely upon hippocampal function and several other tasks that tap into behaviors analogous to those often impaired in schizophrenia. We observed a relationship between genotype at markers known to influence ventral hippocampal volume and working memory at an intermediate memory load. There was no association between genotype at markers known to influence ventral hippocampal volume and spatial reference memory, prepulse inhibition, or elevated plus maze performance. The relevance of these findings for understanding the pathophysiology of schizophrenia are discussed, including the possibility that genetic predisposition toward anterior hippocampal volume reductions and working memory deficits in schizophrenia may be related through a shared genetic locus.