Task-related fronto-striatal functional connectivity during working memory performance in schizophrenia

Linking haploinsufficiency of the autism- and schizophrenia-associated gene Cyfip1 with striatal-limbic-cortical network dysfunction and cognitive inflexibility

Impaired behavioural flexibility is a core feature of neuropsychiatric disorders and is associated with underlying dysfunction of fronto-striatal circuitry. Reduced dosage of Cyfip1 is a risk factor for neuropsychiatric disorder, as evidenced by its involvement in the 15q11.2 (BP1-BP2) copy number variant: deletion carriers are haploinsufficient for CYFIP1 and exhibit a two- to four-fold increased risk of schizophrenia, autism and/or intellectual disability. Here, we model the contributions of Cyfip1 to behavioural flexibility and related fronto-striatal neural network function using a recently developed haploinsufficient, heterozygous knockout rat line. Using multi-site local field potential (LFP) recordings during resting state, we show that Cyfip1 heterozygous rats (Cyfip1+/-) harbor disrupted network activity spanning medial prefrontal cortex, hippocampal CA1 and ventral striatum. In particular, Cyfip1+/- rats showed reduced influence of nucleus accumbens and increased dominance of prefrontal and hippocampal inputs, compared to wildtype controls. Adult Cyfip1+/- rats were able to learn a single cue-response association, yet unable to learn a conditional discrimination task that engages fronto-striatal interactions during flexible pairing of different levers and cue combinations. Together, these results implicate Cyfip1 in development or maintenance of cortico-limbic-striatal network integrity, further supporting the hypothesis that alterations in this circuitry contribute to behavioural inflexibility observed in neuropsychiatric diseases including schizophrenia and autism.

Association between degree centrality and neurocognitive impairments in patients with Schizophrenia: A Longitudinal rs-fMRI Study

BACKGROUND

Evidence indicates that patients with schizophrenia (SZ) experience significant changes in their functional connectivity during antipsychotic treatment. Despite previous reports of changes in brain network degree centrality (DC) in patients with schizophrenia, the relationship between brain DC changes and neurocognitive improvement in patients with SZ after antipsychotic treatment remains elusive.

METHODS

A total of 74 patients with acute episodes of chronic SZ and 53 age- and sex-matched healthy controls were recruited. The Positive and Negative Syndrome Scale (PANSS), Symbol Digit Modalities Test, digital span test (DST), and verbal fluency test were used to evaluate the clinical symptoms and cognitive performance of the patients with SZ. Patients with SZ were treated with antipsychotics for six weeks starting at baseline and underwent MRI and clinical interviews at baseline and after six weeks, respectively. We then divided the patients with SZ into responding (RS) and non-responding (NRS) groups based on the PANSS scores (reduction rate of PANSS ≥50%). DC was calculated and analyzed to determine its correlation with clinical symptoms and cognitive performance.

RESULTS

After antipsychotic treatment, the patients with SZ showed significant improvements in clinical symptoms, semantic fluency performance. Correlation analysis revealed that the degree of DC increase in the left anterior inferior parietal lobe (aIPL) after treatment was negatively correlated with changes in the excitement score (r = -0.256, p = 0.048, adjusted p = 0.080), but this correlation failed the multiple test correction. Patients with SZ showed a significant negative correlation between DC values in the left aIPL and DST scores after treatment, which was not observed at the baseline (r = -0.359, p = 0.005, adjusted p = 0.047). In addition, we did not find a significant difference in DC between the RS and NRS groups, neither at baseline nor after treatment.

CONCLUSIONS

The results suggested that DC changes in patients with SZ after antipsychotic treatment are correlated with neurocognitive performance. Our findings provide new insights into the neuropathological mechanisms underlying antipsychotic treatment of SZ.

Striatal Functional Hypoconnectivity in Patients With Schizophrenia Suffering From Negative Symptoms, Longitudinal Findings

BACKGROUND

Negative symptoms in schizophrenia (SZ), such as apathy and diminished expression, have limited treatments and significantly impact daily life. Our study focuses on the functional division of the striatum: limbic-motivation and reward, associative-cognition, and sensorimotor-sensory and motor processing, aiming to identify potential biomarkers for negative symptoms.

STUDY DESIGN

This longitudinal, 2-center resting-state-fMRI (rsfMRI) study examines striatal seeds-to-whole-brain functional connectivity. We examined connectivity aberrations in patients with schizophrenia (PwSZ), focusing on stable group differences across 2-time points using intra-class-correlation and associated these with negative symptoms and measures of cognition. Additionally, in PwSZ, we used negative symptoms to predict striatal connectivity aberrations at the baseline and used the striatal aberration to predict symptoms 9 months later.

STUDY RESULTS

A total of 143 participants (77 PwSZ, 66 controls) from 2 centers (Berlin/Geneva) participated. We found sensorimotor-striatum and associative-striatum hypoconnectivity. We identified 4 stable hypoconnectivity findings over 3 months, revealing striatal-fronto-parietal-cerebellar hypoconnectivity in PwSZ. From those findings, we found hypoconnectivity in the bilateral associative striatum with the bilateral paracingulate-gyrus and the anterior cingulate cortex in PwSZ. Additionally, hypoconnectivity between the associative striatum and the superior frontal gyrus was associated with lower cognition scores in PwSZ, and weaker sensorimotor striatum connectivity with the superior parietal lobule correlated negatively with diminished expression and could predict symptom severity 9 months later.

CONCLUSIONS

Importantly, patterns of weaker sensorimotor striatum and superior parietal lobule connectivity fulfilled the biomarker criteria: clinical significance, reflecting underlying pathophysiology, and stability across time and centers.

Aberrant Brain Dynamics in Schizophrenia During Working Memory Task: Evidence From a Replication Functional MRI Study

BACKGROUND AND HYPOTHESIS

The integration of information that typifies working memory (WM) operation requires a flexible, dynamic functional relationship among brain regions. In schizophrenia, though WM capacity is prominently impaired at higher loads, the mechanistic underpinnings are unclear. As a result, we lack convincing cognitive remediation of load-dependent deficits. We hypothesize that reduced WM capacity arises from a disruption in dynamic functional connectivity when patients face cognitive demands.

STUDY DESIGN

We calculate the dynamic voxel-wise degree centrality (dDC) across the functional connectome in 142 patients with schizophrenia and 88 healthy controls (HCs) facing different WM loads during an n-back task. We tested associations of the altered variability in dDC and clinical symptoms and identified intermediate connectivity configurations (clustered states) across time during WM operation. These analyses were repeated in another independent dataset of 169 subjects (102 with schizophrenia).

STUDY RESULTS

Compared with HCs, patients showed an increased dDC variability of supplementary motor area (SMA) for the "2back vs. 0back" contrast. This instability at the SMA seen in patients correlated with increased positive symptoms and followed a limited "U-shape" pattern at rest-condition and 2 loads. In the clustering analysis, patients showed reduced centrality in the SMA, superior temporal gyrus, and putamen. These results were replicated in a constrained search in the second independent dataset.

CONCLUSIONS

Schizophrenia is characterized by a load-dependent reduction of stable centrality in SMA; this relates to the severity of positive symptoms, especially disorganized behaviour. Restoring SMA stability in the presence of cognitive demands may have a therapeutic effect in schizophrenia.

Abnormal brain network community structure related to psychological stress in schizophrenia

Recent functional imaging studies in schizophrenia consistently report a disruption of brain connectivity. However, most of these studies analyze the brain connectivity during resting state. Since psychological stress is a major factor for the emergence of psychotic symptoms, we sought to characterize the brain connectivity reconfiguration induced by stress in schizophrenia. We tested the hypothesis that an alteration of the brain's integration-segregation dynamic could be the result of patients with schizophrenia facing psychological stress. To this end, we studied the modular organization and the reconfiguration of networks induced by a stress paradigm in forty subjects (twenty patients and twenty controls), thus analyzing the dynamics of the brain in terms of integration and segregation processes by using 3T-fMRI. Patients with schizophrenia did not show statistically significant differences during the control task compared with controls, but they showed an abnormal community structure during stress condition and an under-connected reconfiguration network with a reduction of hub nodes, suggesting a deficit of integration dynamic with a greater compromise of the right hemisphere. These results provide evidence that schizophrenia has a normal response to undemanding stimuli but shows a disruption of brain functional connectivity between key regions involved in stress response, potentially leading to altered functional brain dynamics by reducing integration capacity and showing deficits recruiting right hemisphere regions. This could in turn underlie the hyper-sensitivity to stress characteristic of schizophrenia.

Prefrontal and Striatal Dopamine Release Are Inversely Correlated in Schizophrenia

BACKGROUND

The dopamine (DA) hypothesis postulates hyperactivity of subcortical DA transmission and hypoactivity of cortical DA in schizophrenia (SCH). Positron emission tomography provides the ability to assess this hypothesis in humans. However, no studies have examined the relationship between cortical DA and striatal DA in this illness.

METHODS

D_2/3 receptor radiotracer [¹¹C]FLB457 BP_ND (binding potential relative to nondisplaceable uptake) was measured in 14 off-medication subjects with SCH and 14 healthy control (HC) subjects at baseline and after the administration of 0.5 mg/kg oral d-amphetamine. The amphetamine-induced change in BP_ND (ΔBP_ND) was calculated as the difference between BP_ND in the postamphetamine condition and BP_ND in the baseline condition and expressed as a percentage of BP_ND at baseline. DA release in the striatum using the radiotracer [¹¹C]NPA was also measured in these subjects.

RESULTS

[¹¹C]FLB457 ΔBP_ND was greater in the HC group compared with the SCH group (F_1,26 = 5.7; p = .02) with significant differences in [¹¹C]FLB457 ΔBP_ND seen across cortical brain regions. Only in the SCH group was a significant negative correlation observed between [¹¹C]FLB457 ΔBP_ND in the dorsolateral prefrontal cortex and [¹¹C]NPA ΔBP_ND in the dorsal caudate (r = -0.71, p = .005).

CONCLUSIONS

Subjects with SCH demonstrated deficits of DA release in cortical brain regions relative to HC subjects. Examining both cortical and striatal DA release in the same subjects demonstrated an inverse relationship between cortical DA release and striatal DA release in SCH not present in HC subjects, providing support for the current DA hypothesis of SCH.

Dorsal striatial hypoconnectivity predicts antipsychotic medication treatment response in first-episode psychosis and unmedicated patients with schizophrenia

INTRODUCTION

The dorsal striatum, comprised of the caudate and putamen, is implicated in the pathophysiology of psychosis spectrum disorders. Given the high concentration of dopamine receptors in the striatum, striatal dopamine imbalance is a likely cause in cortico-striatal dysconnectivity. There is great interest in understanding the relationship between striatal abnormalities in psychosis and antipsychotic treatment response, but few studies have considered differential involvement of the caudate and putamen. This study's goals were twofold. First, identify patterns of dorsal striatal dysconnectivity for the caudate and putamen separately in patients with a psychosis spectrum disorder; second, determine if these dysconnectivity patterns were predictive of treatment response.

METHODS

Using resting state functional connectivity, we evaluated dorsal striatal connectivity using separate bilateral caudate and putamen seed regions in two cohorts of subjects: a cohort of 71 medication-naïve first episode psychosis patients and a cohort of 42 unmedicated patients with schizophrenia (along with matched controls). Patient and control connectivity maps were contrasted for each cohort. After receiving 6 weeks of risperidone treatment, patients' clinical response was calculated. We used regression analyses to determine the relationship between baseline dysconnectivity and treatment response.

RESULTS

This dysconnectivity was also predictive of treatment response in both cohorts.

DISCUSSION

These findings suggest that the caudate may be more of a driving factor than the putamen in early cortico-striatal dysconnectivity.

Brain structural abnormalities of the associative striatum in adolescents and young adults at genetic high-risk of schizophrenia: Implications for illness endophenotypes

OBJECTIVE

Dysfunction in cortico-striatal circuitry represents a core component of the pathophysiology in schizophrenia (SZ) but its potential as a candidate endophenotype of the illness is often confounded by neuroleptic medication.

METHODS

Accordingly, 26 adolescent and young adult participants at genetic high-risk for schizophrenia, but who were asymptomatic and neuroleptic naïve, and 28 age-matched controls underwent 1.5T structural magnetic resonance imaging of the striatum, manually parcellated into limbic (LST), associative (AST), and sensorimotor (SMST) functional subregions.

RESULTS

In relation to their age peers, participants at genetic high-risk for schizophrenia showed overall lower striatal gray matter volume with their most pronounced loss, bilaterally in the AST, but not the LST or SMST. Neuropsychological testing revealed reduced executive functioning for genetically at-risk participants, although the groups did not differ significantly in overall intelligence or oral reading. For controls but not for at-genetic high-risk participants, stronger executive functioning correlated with increased bilateral AST volume.

CONCLUSIONS

Reduced bilateral AST volume in genetic high-risk adolescents and young adults, accompanied by heritable loss of higher cognitive brain-behavior relationships, might serve as a useful endophenotype of SZ.

Unraveling schizophrenia replicable functional connectivity disruption patterns across sites

Functional connectivity (FC) disruption is a remarkable characteristic of schizophrenia. However, heterogeneous patterns reported across sites severely hindered its clinical generalization. Based on qualified nodal-based FC of 340 schizophrenia patients (SZ) and 348 normal controls (NC) acquired from seven different scanners, this study compared four commonly used site-effect correction methods in removing the site-related heterogeneities, and then tried to cluster the abnormal FCs into several replicable and independent disrupted subnets across sites, related them to clinical symptoms, and evaluated their potentials in schizophrenia classification. Among the four site-related heterogeneity correction methods, ComBat harmonization (F1 score: 0.806 ± 0.145) achieved the overall best balance between sensitivity and false discovery rate in unraveling the aberrant FCs of schizophrenia in the local and public data sets. Hierarchical clustering analysis identified three replicable FC disruption subnets across the local and public data sets: hypo-connectivity within sensory areas (Net1), hypo-connectivity within thalamus, striatum, and ventral attention network (Net2), and hyper-connectivity between thalamus and sensory processing system (Net3). Notably, the derived composite FC within Net1 was negatively correlated with hostility and disorientation in the public validation set (p < .05). Finally, the three subnet-specific composite FCs (Best area under the receiver operating characteristic curve [AUC] = 0.728) can robustly and meaningfully discriminate the SZ from NC with comparable performance with the full identified FCs features (best AUC = 0.765) in the out-of-sample public data set (Z = -1.583, p = .114). In conclusion, ComBat harmonization was most robust in detecting aberrant connectivity for schizophrenia. Besides, the three subnet-specific composite FC measures might be replicable neuroimaging markers for schizophrenia.

High-Frequency Transcranial Random Noise Stimulation over the Left Prefrontal Cortex Increases Resting-State EEG Frontal Alpha Asymmetry in Patients with Schizophrenia

Reduced left-lateralized electroencephalographic (EEG) frontal alpha asymmetry (FAA), a biomarker for the imbalance of interhemispheric frontal activity and motivational disturbances, represents a neuropathological attribute of negative symptoms of schizophrenia. Unidirectional high-frequency transcranial random noise stimulation (hf-tRNS) can increase the excitability of the cortex beneath the stimulating electrode. Yet, it is unclear if hf-tRNS can modulate electroencephalographic FAA in patients with schizophrenia. We performed a randomized, double-blind, sham-controlled clinical trial to contrast hf-tRNS and sham stimulation for treating negative symptoms in 35 schizophrenia patients. We used electroencephalography to investigate if 10 sessions of hf-tRNS delivered twice-a-day for five consecutive weekdays would modulate electroencephalographic FAA in schizophrenia. EEG data were collected and FAA was expressed as the differences between common-log-transformed absolute power values of frontal right and left hemisphere electrodes in the alpha frequency range (8-12.5 Hz). We found that hf-tRNS significantly increased FAA during the first session of stimulation (p = 0.009) and at the 1-week follow-up (p = 0.004) relative to sham stimulation. However, FAA failed to predict and surrogate the improvement in the severity of negative symptoms with hf-tRNS intervention. Together, our findings suggest that modulating electroencephalographic frontal alpha asymmetry by using unidirectional hf-tRNS may play a key role in reducing negative symptoms in patients with schizophrenia.

The effect of transcranial direct current stimulation combined with working memory training on working memory deficits in schizophrenic patients: study protocol for a randomized controlled trial

Background

Working memory deficits are one of the core and most characteristic clinical features of cognitive impairment in schizophrenia. Cognitive training can improve the cognitive function of patients with schizophrenia. However, the overall and transfer effects of working memory treatment (WMT) require improvement. Numerous studies have confirmed that transcranial direct current stimulation (tDCS) enhances neuroplasticity in the brain, providing a new treatment approach for cognitive impairment in patients with schizophrenia. We hypothesize that a training mode combining “preheating” (tDCS, which changes the neural activity of working memory-related brain regions) and “ironing” (WMT) affords greater cognitive improvements than WMT alone. In addition, this study aims to examine the mechanisms underlying the superiority of tDCS combined with WMT in improving cognitive function in patients with schizophrenia.

Methods

This study will include 120 patients with schizophrenia aged 18–60 years. The patients will be randomized into four groups: the study group (tDCS + WMT), tDCS group (tDCS + simple response training, SRT), WMT group (sham tDCS + WMT), and control group (sham tDCS + SRT). Patients will receive 20-min, 2 mA sessions of active or sham tDCS twice a day on weekdays for 2 weeks. Each stimulation will be immediately followed by a 1 − 2-min rest and 40 min of WMT or SRT. The primary outcome is cognitive function, measured using Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) and some subscales of the MATRICS Consensus Cognitive Battery (MCCB). The secondary outcomes are other behavioral measures, variations in brain imaging, and serum levels of brain-derived neurotrophic factor (BDNF). All outcomes will be measured at baseline, post-treatment, and 3-month follow-up, except for brain imaging and BDNF levels, which will be measured at baseline and post-treatment only.

Discussion

If tDCS combined with WMT results in significant improvements and prolonged effects on working memory, this method could be considered as a first-line clinical treatment for schizophrenia. Moreover, these results could provide evidence-based support for the development of other approaches to improve cognitive function in patients with schizophrenia, especially by enhancing WMT effects.

Trial registration

Chictr.org.cn; ChiCTR2200063844. Registered on September 19, 2022.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13063-022-06776-x.

Mechanisms underlying dorsolateral prefrontal cortex contributions to cognitive dysfunction in schizophrenia

Kraepelin, in his early descriptions of schizophrenia (SZ), characterized the illness as having "an orchestra without a conductor." Kraepelin further speculated that this "conductor" was situated in the frontal lobes. Findings from multiple studies over the following decades have clearly implicated pathology of the dorsolateral prefrontal cortex (DLPFC) as playing a central role in the pathophysiology of SZ, particularly with regard to key cognitive features such as deficits in working memory and cognitive control. Following an overview of the cognitive mechanisms associated with DLPFC function and how they are altered in SZ, we review evidence from an array of neuroscientific approaches addressing how these cognitive impairments may reflect the underlying pathophysiology of the illness. Specifically, we present evidence suggesting that alterations of the DLPFC in SZ are evident across a range of spatial and temporal resolutions: from its cellular and molecular architecture, to its gross structural and functional integrity, and from millisecond to longer timescales. We then present an integrative model based upon how microscale changes in neuronal signaling in the DLPFC can influence synchronized patterns of neural activity to produce macrocircuit-level alterations in DLPFC activation that ultimately influence cognition and behavior. We conclude with a discussion of initial efforts aimed at targeting DLPFC function in SZ, the clinical implications of those efforts, and potential avenues for future development.

Involvement of cerebellar and subcortical connector hubs in schizophrenia

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Hubs with altered connectivity to multiple networks were identified in patients.

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Identified hubs were located in the cerebellum, midbrain, thalamus, and insula.

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In controls, these hubs were strongly connected with the basal ganglia network.

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Hubs’ connections to large-scale networks were associated with clinical data.

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Their connections were also highly predictive of patients from controls.

Background

Schizophrenia is considered a brain connectivity disorder in which functional integration within the brain fails. Central to the brain’s integrative function are connector hubs, brain regions characterized by strong connections with multiple networks. Given their critical role in functional integration, we hypothesized that connector hubs, including those located in the cerebellum and subcortical regions, are severely impaired in patients with schizophrenia.

Methods

We identified brain voxels with significant connectivity alterations in patients with schizophrenia (n = 76; men = 43) compared to healthy controls (n = 80; men = 43) across multiple large-scale resting state networks (RSNs) using a network metric called functional connectivity overlap ratio (FCOR). From these voxels, candidate connector hubs were identified and verified using seed-based connectivity analysis.

Results

We found that most networks exhibited connectivity alterations in the patient group. Specifically, connectivity with the basal ganglia and high visual networks was severely affected over widespread brain areas in patients, affecting subcortical and cerebellar regions and the regions involved in visual and sensorimotor processing. Furthermore, we identified critical connector hubs in the cerebellum, midbrain, thalamus, insula, and calcarine with connectivity to multiple RSNs affected in the patients. FCOR values of these regions were also associated with clinical data and could classify patient and control groups with > 80 % accuracy.

Conclusions

These findings highlight the critical role of connector hubs, particularly those in the cerebellum and subcortical regions, in the pathophysiology of schizophrenia and the potential role of FCOR as a clinical biomarker for the disorder.

The Association Between Lentiform Nucleus Function and Cognitive Impairments in Schizophrenia

Introduction: Cognitive decline is the core schizophrenia symptom, which is now well accepted. Holding a role in various aspects of cognition, lentiform nucleus (putamen and globus pallidus) dysfunction contributes to the psychopathology of this disease. However, the effects of lentiform nucleus function on cognitive impairments in schizophrenia are yet to be investigated.

Objectives: We aim to detect the fractional amplitude of low-frequency fluctuation (fALFF) alterations in patients with schizophrenia, and examine how their behavior correlates in relation to the cognitive impairments of the patients.

Methods: All participants underwent magnetic resonance imaging (MRI) and cognitive assessment (digit span and digit symbol coding tests). Screening of brain regions with significant changes in fALFF values was based on analysis of the whole brain. The data were analyzed between Jun 2020 and Mar 2021. There were no interventions beyond the routine therapy determined by their clinicians on the basis of standard clinical practice.

Results: There were 136 patients (75 men and 61 women, 24.1 ± 7.4 years old) and 146 healthy controls (82 men and 64 women, 24.2 ± 5.2 years old) involved in the experiments seriatim. Patients with schizophrenia exhibited decreased raw scores in cognitive tests (p < 0.001) and increased fALFF in the bilateral lentiform nuclei (left: 67 voxels; x = −24, y = −6, z = 3; peak t-value = 6.90; right: 16 voxels; x = 18, y = 0, z = 3; peak t-value = 6.36). The fALFF values in the bilateral lentiform nuclei were positively correlated with digit span-backward test scores (left: r = 0.193, p = 0.027; right: r = 0.190, p = 0.030), and the right lentiform nucleus was positively correlated with digit symbol coding scores (r = 0.209, p = 0.016).

Conclusion: This study demonstrates that cognitive impairments in schizophrenia are associated with lentiform nucleus function as revealed by MRI, involving working memory and processing speed.

Deciphering the frontostriatal circuitry through the fiber dissection technique: direct structural evidence on the morphology and axonal connectivity of the fronto-caudate tract

OBJECTIVE

The authors sought to investigate the very existence and map the topography, morphology, and axonal connectivity of a thus far ill-defined subcortical pathway known as the fronto-caudate tract (FCT) since there is a paucity of direct structural evidence regarding this pathway in the relevant literature.

METHODS

Twenty normal adult cadaveric formalin-fixed cerebral hemispheres (10 left and 10 right) were explored through the fiber microdissection technique. Lateral to medial and medial to lateral dissections were carried out in a tandem manner in all hemispheres. Attention was focused on the prefrontal area and central core since previous diffusion tensor imaging studies have recorded the tract to reside in this territory.

RESULTS

In all cases, the authors readily identified the FCT as a fan-shaped pathway lying in the most medial layer of the corona radiata and traveling across the subependymal plane before terminating on the superolateral margin of the head and anterior part of the body of the caudate nucleus. The FCT could be adequately differentiated from adjacent fiber tracts and was consistently recorded to terminate in Brodmann areas 8, 9, 10, and 11 (anterior pre-supplementary motor area and the dorsolateral, frontopolar, and fronto-orbital prefrontal cortices). The authors were also able to divide the tract into a ventral and a dorsal segment according to the respective topography and connectivity observed. Hemispheric asymmetries were not observed, but instead the authors disclosed asymmetry within the FCT, with the ventral segment always being thicker and bulkier than the dorsal one.

CONCLUSIONS

By using the fiber microdissection technique, the authors provide sound structural evidence on the topography, morphology, and connectional anatomy of the FCT as a distinct part of a wider frontostriatal circuitry. The findings are in line with the tract's putative functional implications in high-order motor and behavioral processes and can potentially inform current surgical practice in the fields of neuro-oncology and functional neurosurgery.

Altered effective connectivity within an oculomotor control network in individuals with schizophrenia

Rapid inhibition or modification of actions is a crucial cognitive ability, which is impaired in persons with schizophrenia (SZP). Primate neurophysiology studies have identified a network of brain regions that subserves control over gaze. Here, we examine effective connectivity within this oculomotor control network in SZP and healthy controls (HC). During fMRI, participants performed a stop-signal task variant in which they were instructed to saccade to a visual target (no-step trials) unless a second target appeared (redirect trials); on redirect trials, participants were instructed to inhibit the planned saccade and redirect to the new target. We compared functional responses on redirect trials to no-step trials and used dynamic causal modelling (DCM) to examine group differences in network effective connectivity. Behaviorally, SZP were less efficient at inhibiting, which was related to their employment status. Compared to HC, they showed a smaller difference in activity between redirect trials and no-step trials in frontal eye fields (FEF), supplementary eye fields (SEF), inferior frontal cortex (IFC), thalamus, and caudate. DCM analyses revealed widespread group differences in effective connectivity across the task, including different patterns of self-inhibition in many nodes in SZP. Group differences in how effective connectivity was modulated on redirect trials revealed differences between the FEF and SEF, between the SEF and IFC, between the superior colliculus and the thalamus, and self-inhibition within the FEF and caudate. These results provide insight into the neural mechanisms of inefficient inhibitory control in individuals with schizophrenia.

Neurocognitive correlates of working memory and emotional processing in postpartum psychosis: an fMRI study

BACKGROUND

Postpartum psychosis (PP) is a severe postpartum disorder. While working memory and emotional processing-related brain function are consistently impaired in psychoses unrelated to the puerperium, no studies have investigated them in PP.

METHODS

Twenty-four women at risk of developing PP (11 developed an episode - PE; 13 remained well - NPE) and 20 healthy postpartum women completed two functional magnetic resonance imaging tasks within a year of delivery: working memory (n-back) and emotional face recognition (fearful faces). We compared women at-risk of PP to controls, as well as NPE, PE, and controls to test for potential effects of a PP episode occurrence.

RESULTS

Women at-risk of PP and PE showed hyperactivation of lateral visual areas, precuneus, and posterior cingulate during the n-back task. The at-risk group as a whole, as well as the PE and NPE groups, showed hyperconnectivity of the right dorsolateral prefrontal cortex (DLPFC) with various parieto-occipito-temporo-cerebellar regions compared to controls during several n-back conditions. Increases in connectivity between the right DLPFC and ipsilateral middle temporal gyrus were observed in the PE group compared to NPE during 2-back. During the fearful faces task, at-risk women as a group showed hyperactivation of fronto-cingulo-subcortical regions, and hypoconnectivity between the left amygdala and ipsilateral occipito-parietal regions compared to controls. No significant performance differences were observed.

CONCLUSIONS

These results present preliminary evidence of a differential nature of functional brain abnormalities in PP compared to the typically observed reduced connectivity with the DLPFC in psychoses unrelated to puerperium, such as bipolar disorder.

Adjunct high-frequency transcranial random noise stimulation over the lateral prefrontal cortex improves negative symptoms of schizophrenia: A randomized, double-blind, sham-controlled pilot study

High-frequency transcranial random noise stimulation (hf-tRNS) is a non-invasive neuromodulatory technique capable of increasing human cortex excitability. There were only published case reports on the use of hf-tRNS targeting the lateral prefrontal cortex in treating negative symptoms of schizophrenia, thus necessitating systematic investigation. We designed a randomized, double-blind, sham-controlled trial in a cohort of stabilized schizophrenia patients to examine the efficacy of add-on hf-tRNS (100-640 Hz; 2 mA; 20 min) using a high definition 4 × 1 electrode montage (anode AF3, cathodes AF4, F2, F6, and FC4) in treating negative symptoms (ClinicalTrials.gov ID: NCT04038788). Participants received either active hf-tRNS or sham twice daily for 5 consecutive weekdays. Primary outcome measure was the change over time in the Positive and Negative Syndrome Scale Factor Score for Negative Symptoms (PANSS-FSNS), which was measured at baseline, after 10-session stimulation, and at one-week and one-month follow-ups. Among 36 randomized patients, 35 (97.2%) completed the trial. Intention-to-treat analysis showed a significantly greater decrease in PANSS-FSNS score after active (-17.11%) than after sham stimulation (-1.68%), with a large effect size (Cohen's d = 2.16, p < 0.001). The beneficial effect lasted for up to one month. In secondary-outcome analyses, the authors observed improvements with hf-tRNS of disorganization symptoms, unawareness of negative symptoms, subjective response to taking antipsychotics, and antipsychotic-induced extrapyramidal symptoms. No effects were observed on the neurocognitive performance and other outcome measures. Overall, hf-tRNS was safe and efficacious in improving negative symptoms. Our promising findings should be confirmed in a larger sample of patients with predominant negative symptoms.

Association between functional and structural connectivity of the corticostriatal network in people with schizophrenia and unaffected first-degree relatives

BACKGROUND

Dysfunction of the corticostriatal network has been implicated in the pathophysiology of schizophrenia, but findings are inconsistent within and across imaging modalities. We used multimodal neuroimaging to analyze functional and structural connectivity in the corticostriatal network in people with schizophrenia and unaffected first-degree relatives.

METHODS

We collected resting-state functional magnetic resonance imaging and diffusion tensor imaging scans from people with schizophrenia (n = 47), relatives (n = 30) and controls (n = 49). We compared seed-based functional and structural connectivity across groups within striatal subdivisions defined a priori.

RESULTS

Compared with controls, people with schizophrenia had altered connectivity between the subdivisions and brain regions in the frontal and temporal cortices and thalamus; relatives showed different connectivity between the subdivisions and the right anterior cingulate cortex (ACC) and the left precuneus. Post-hoc t tests revealed that people with schizophrenia had decreased functional connectivity in the ventral loop (ventral striatum-right ACC) and dorsal loop (executive striatum-right ACC and sensorimotor striatum-right ACC), accompanied by decreased structural connectivity; relatives had reduced functional connectivity in the ventral loop and the dorsal loop (right executive striatum-right ACC) and no significant difference in structural connectivity compared with the other groups. Functional connectivity among people with schizophrenia in the bilateral ventral striatum-right ACC was correlated with positive symptom severity.

LIMITATIONS

The number of relatives included was moderate. Striatal subdivisions were defined based on a relatively low threshold, and structural connectivity was measured based on fractional anisotropy alone.

CONCLUSION

Our findings provide insight into the role of hypoconnectivity of the ventral corticostriatal system in people with schizophrenia.

Intermittent theta burst stimulation (iTBS) combined with working memory training to improve cognitive function in schizophrenia: study protocol for a randomized controlled trial

BACKGROUND

Working memory deficit is one of the most critical complex cognitive impairments in schizophrenia. Repetitive transcranial magnetic stimulation (rTMS) is an effective adjuvant therapy, but not still unsatisfactory. Intermittent theta burst stimulation (iTBS), which has recently been used in clinical practice, may have faster and stronger effects comparing the traditional model (10-Hz high-frequency rTMS). A large number of studies have showed that rTMS, especially iTBS, can enhance the neural plasticity of the brain, and cognitive training can improve the cognitive function of schizophrenia. Is there any facilitation effect of iTBS add on cognitive training (such as working memory training, WMT) on cognitive function enhancement in schizophrenia is still unknown.

METHODS/DESIGN

The proposed study is designed of a double-center, double-blinded, randomized controlled trial that will include 200 schizophrenia patients between 18 and 45 years of age. The patients will be randomized to four groups, i.e., the study group (iTBS+WMT), WMS control group (iTBS+ Simple Response Training (SRT)), iTBS control group (sham iTBS+WMT), and placebo control (sham iTBS+SRT). The patients will receive 3 min 20 s of real or sham stimulation, followed by a short 1-2-min rest and 40 min of WMT training or SRT immediately. Neuropsychological and clinical symptom assessments, with functional and structural MRI, will be performed on baseline, post-treatment, and 3- and 6-month follow-up periods. The primary outcome is cognitive function measured by the MATRICS Consensus Cognitive Battery (MCCB). The secondary outcomes are changes in neuroplasticity, as measured by MRI and other behavioral assessments.

DISCUSSION

The aim of our study is to explore the facilitation effects of iTBS added on WMT in improving cognitive function of schizophrenia. That means, patients with schizophrenia will benefit more in cognitive function improvement from the combination training mode of "preheating (iTBS stimulation changes the neural activity of working memory-related brain regions) and ironning (working memory training)." And the long-term effects of this combined training model will be assessed at a 6-month follow-up period. In case of a significant improvement of working memory with a prolonged effect, the iTBS combined with WMT protocol could be considered as a first-line clinical protocol in schizophrenia treatment. More broadly, the potential for increased universality and efficiency of rTMS with the iTBS model to enhance the neural plasticity of the brain should have a more positive effect on cognitive function in schizophrenia.

TRIAL REGISTRATION

chictr.org.cn ChiCTR1900023405 . Registered on 25 May 2019.

Clinical and cognitive correlates of childhood attention-deficit/hyperactivity disorder in first-episode psychosis: A controlled study

The relationship between childhood attention-deficit/hyperactivity disorder (c-ADHD) and psychosis has been understudied. Cognitive dysfunction is a core feature of both disorders, but no previous study has investigated whether first-episode psychosis (FEP) with c-ADHD (FEP-ADHD⁺) presents a different cognitive profile than FEP without c-ADHD (FEP-ADHD^-). One hundred and thirty-three FEP outpatients were screened for c-ADHD through a diagnostic interview and underwent a comprehensive clinical and cognitive assessment with the MATRICS Consensus Cognitive Battery (MCCB). Cognitive differences among FEP groups, and a group of 65 healthy controls (HCs) were analysed by multivariate analysis of covariance. Nearly 25% of FEP fulfilled criteria for c-ADHD. Both FEP groups performed worse than HCs in speed processing, executive function and social cognition, but only the FEP-ADHD⁺group was significantly more impaired than the HC group in attention (F = 4.35; p = 0.04). Only the Trail Making Test A (TMT-A) (F = 6.99; p = 0.01) within the domain of processing speed and the Neuropsychological Assessment Battery (NAB) (F = 6.46; p = 0.01) within the domain of executive function reliably differentiated the two clinical groups. The FEP groups did not differ in the severity of psychopathology, but the FEP-ADHD⁺reported fewer years of education than the FEP-ADHD^- and were more likely to use tobacco and cannabis and to require higher doses of antipsychotics to achieve a clinical response. In conclusion, we found a gradient of severity in cognitive performance between groups, with FEP-ADHD⁺ having the greatest cognitive impairment. Our results suggest that FEP-ADHD⁺ represents a subgroup with a worse prognosis than FEP-ADHD^-.

The role of genes affected by human evolution marker GNA13 in schizophrenia

Numerous variants associated with increased risk for SCZ have undergone positive selection and were associated with human brain development, but which brain regions and developmental stages were influenced by the positive selection for SCZ risk alleles are unclear. We analyzed SCZ using summary statistics from a genome-wide association study (GWAS) from the Psychiatric Genomics Consortium (PGC). Machine-learning scores were used to investigate two natural-selection scenarios: complete selection (loci where a selected allele has reached fixation) and incomplete selection (loci where a selected allele has not yet reached fixation). Based on the p value of single nucleotide polymorphisms (SNPs) with selection scores in the top 5%, we formed five subgroups: p < 0.0001, 0.001, 0.01, 0.05, or 0.1. We found that 48 and 29 genes (p < 0.0001) in complete and incomplete selection, respectively, were enrichedfor the transcriptionalco-expressionprofilein theprenatal dorsolateral prefrontal cortex (DFC), inferior parietal cortex (IPC), and ventrolateral prefrontal cortex (VFC). Core genes (GNA13, TBC1D19, and ZMYM4) involved in regulating early brain development were identified in these three brain regions. RNA sequencing for primary cortical neurons that were transfected Gna13 overexpressed lentivirus demonstrated that 135 gene expression levels changed in the Gna13 overexpressed groups compared with the controls. Gene-set analysis identified important associations among common variants of these 13 genes, which were associated with neurodevelopment and putamen volume [p = 0.031; family-wise error correction (FWEC)], SCZ (p = 0.022; FWEC). The study indicate that certain SCZ risk alleles were likely to undergo positive selection during human evolution due to their involvement in the development of prenatal DFC, IPC and VFC, and suggest that SCZ is related to abnormal neurodevelopment.

Distinct striatum pathways connected to salience network predict symptoms improvement and resilient functioning in schizophrenia following risperidone monotherapy

Abnormal interactions between the striatum and salience network (SN) are considered as etiological and treatment-sensitive marker in schizophrenia. However, whether alterations in the intrinsic dynamics as reflected by resting-state functional connectivity (RSFC) between the striatum and salience network may predict treatment response to the widely used antipsychotic treatment strategies (risperidone, monotherapy) has not been examined systematically. To this end, treatment-naive first-episode schizophrenia patients (n = 41) underwent task-free resting-state fMRI assessment before (baseline) and after 8 weeks of risperidone monotherapy (n = 38). Intrinsic connectivity between striatal sub-regions and core salience processing nodes were examined and compared to carefully matched healthy controls (HC) to determine disorder-specific and treatment-predictive neural markers. Findings demonstrate hypo-connectivity of both ventral and dorsal striatal-SN pathways in patients at baseline. Importantly, specifically the dorsal striatal pathway at baseline could predict negative symptoms improvement in patients; while ventral striatal pathways could predict positive symptoms improvement. Together, results indicate that distinct striatal-SN pathways represent specific treatment-success markers for the effects of risperidone, suggesting that alterations in dorsal versus ventral striatal network markers may represent brain-based markers for specific symptomatologic improvements following risperidone mono-therapy.

Neurocognitive Profiles of Older Adults with Working-Memory Dysfunction

Individuals differ in how they perceive, remember, and think. There is evidence for the existence of distinct subgroups that differ in cognitive performance within the older population. However, it is less clear how individual differences in cognition in old age are linked to differences in brain-based measures. We used latent-profile analysis on n-back working-memory (WM) performance to identify subgroups in a large sample of older adults (n = 181; age = 64–68 years). Our analysis identified one larger normal subgroup with higher performance (n = 113; 63%), and a second smaller subgroup (n = 55; 31%) with lower performance. The low-performing subgroup showed weaker load-dependent BOLD modulation and lower connectivity within the fronto-parietal network (FPN) as well as between FPN and striatum during n-back, along with lower FPN connectivity at rest. This group also exhibited lower FPN structural integrity, lower frontal dopamine D2 binding potential, inferior performance on offline WM tests, and a trend-level genetic predisposition for lower dopamine-system efficiency. By contrast, this group exhibited relatively intact episodic memory and associated brain measures (i.e., hippocampal volume, structural, and functional connectivity within the default-mode network). Collectively, these data provide converging evidence for the existence of a group of older adults with impaired WM functioning characterized by reduced cortico-striatal coupling and aberrant cortico-cortical integrity within FPN.

Brain Abnormalities in Different Phases of Working Memory in Schizophrenia: An Integrative Multi-Modal MRI Study

The current study aimed to examine both gray matter and functional activity changes in schizophrenia by combing both structural and task-related functional magnetic resonance imaging (fMRI). Nineteen patients with schizophrenia and 17 controls were recruited. The fMRI scan was performed while performing a working memory (WM) task. In terms of task performance, accuracy did not differ between groups, but there were significant differences in reaction time. Compared with controls, patients exhibited decreased functional activation in prefrontal areas, insula, lingual gyrus, and superior temporal gyrus during different phases of WM. The subcallosal cortex showed increased activation. Intriguingly, a structural-functional correlation was found in the left dorsolateral prefrontal cortex, anterior cingulate cortex, and subcallosal cortex in patients when performing high-load WM task. This study demonstrated both impaired gray matter volume and functional activation during WM in schizophrenia, suggesting structural and functional impairments. The structural-functional correlation in schizophrenia suggested that structural damage in schizophrenia might induce a decreased ability to modulate functional response in accordance with increasing task difficulty.

Aberrant Frontostriatal Connectivity in Negative Symptoms of Schizophrenia

Negative symptoms represent a distinct component of psychopathology in schizophrenia (SCZ) and are a stable construct over time. Although impaired frontostriatal connectivity has been frequently described in SCZ, its link with negative symptoms has not been carefully studied. We tested the hypothesis that frontostriatal connectivity at rest may be associated with the severity of negative symptoms in SCZ. Resting state functional connectivity (rsFC) data from 95 mostly medicated patients with SCZ and 139 healthy controls (HCs) were acquired. Negative symptoms were assessed using the Brief Negative Symptom Scale. The study analyzed voxel-wise rsFC between 9 frontal "seed regions" and the entire striatum, with the intention to reduce potential biases introduced by predefining any single frontal or striatal region. SCZ showed significantly reduced rsFC between the striatum and the right medial and lateral orbitofrontal cortex (OFC), lateral prefrontal cortex, and rostral anterior cingulate cortex compared with HCs. Further, rsFC between the striatum and the right medial OFC was significantly associated with negative symptom severity. The involved striatal regions were primarily at the ventral putamen. Our results support reduced frontostriatal functional connectivity in SCZ and implicate striatal connectivity with the right medial OFC in negative symptoms. This task-independent resting functional magnetic resonance imaging study showed that medial OFC-striatum functional connectivity is reduced in SCZ and associated with severity of negative symptoms. This finding supports a significant association between frontostriatal connectivity and negative symptoms and thus may provide a potential circuitry-level biomarker to study the neurobiological mechanisms of negative symptoms.

Aberrant fronto-striatal connectivity and fine motor function in schizophrenia

Abnormal fine motor function is a frequent finding in schizophrenia and has been linked to structural and functional brain alterations. However, whether fine motor function is related to functional alterations within the motor system remains unclear. The aim of this study was to assess whether abnormalities in resting-state functional connectivity are present in schizophrenia patients and to investigate how these abnormalities may be related to fine motor function. We examined 19 schizophrenia patients and 16 healthy controls using resting-state functional connectivity for 11 bilateral regions of interest. Fine motor function was assessed on a set of copying tasks and the Symbol-Digit-Substitution Test. We found significantly reduced functional connectivity between the left caudate nucleus and bilateral dorsolateral prefrontal cortex (DLPFC) and between the left putamen and bilateral supplementary motor area (SMA) proper in patients compared to controls. Altered connectivity from DLPFC to caudate nucleus was related to fine motor tasks, which are sensitive to psychomotor speed, whereas aberrant connectivity between the SMA proper and putamen was associated to both, fine motor task, which are sensitive to psychomotor speed and to speed of information processing. Our findings emphasize the role of fronto-striatal connections in the pathogenesis of fine motor impairments in schizophrenia.

Role of basal ganglia neurocircuitry in the pathology of psychiatric disorders

Over the last few decades, advances in human and animal-based techniques have greatly enhanced our understanding of the neural mechanisms underlying psychiatric disorders. Many of these studies have indicated connectivity between and alterations within basal ganglia structures to be particularly pertinent to the development of symptoms associated with several of these disorders. Here we summarize the connectivity, molecular composition, and function of sites within basal ganglia neurocircuits. Then we review the current literature from both human and animal studies concerning altered basal ganglia function in five common psychiatric disorders: obsessive-compulsive disorder, substance-related and addiction disorders, major depressive disorder, generalized anxiety disorder, and schizophrenia. Finally, we present a model based upon the findings of these studies that highlights the striatum as a particularly attractive target for restoring normal function to basal ganglia neurocircuits altered within psychiatric disorder patients.

Nonsocial and social cognition in schizophrenia: current evidence and future directions

Cognitive impairment in schizophrenia involves a broad array of nonsocial and social cognitive domains. It is a core feature of the illness, and one with substantial implications for treatment and prognosis. Our understanding of the causes, consequences and interventions for cognitive impairment in schizophrenia has grown substantially in recent years. Here we review a range of topics, including: a) the types of nonsocial cognitive, social cognitive, and perceptual deficits in schizophrenia; b) how deficits in schizophrenia are similar or different from those in other disorders; c) cognitive impairments in the prodromal period and over the lifespan in schizophrenia; d) neuroimaging of the neural substrates of nonsocial and social cognition, and e) relationships of nonsocial and social cognition to functional outcome. The paper also reviews the considerable efforts that have been directed to improve cognitive impairments in schizophrenia through novel psychopharmacology, cognitive remediation, social cognitive training, and alternative approaches. In the final section, we consider areas that are emerging and have the potential to provide future insights, including the interface of motivation and cognition, the influence of childhood adversity, metacognition, the role of neuroinflammation, computational modelling, the application of remote digital technology, and novel methods to evaluate brain network organization. The study of cognitive impairment has provided a way to approach, examine and comprehend a wide range of features of schizophrenia, and it may ultimately affect how we define and diagnose this complex disorder.

Effects of Amisulpride Adjunctive Therapy on Working Memory and Brain Metabolism in the Frontal Cortex of Patients with Schizophrenia: A Preliminary Positron Emission Tomography/Computerized Tomography Investigation

Objective

Dopamine plays a significant role in working memory by acting as a key neuromodulator between brain networks. Additionally, treatment of patients with schizophrenia using amisulpride, a pure dopamine class 2/3 receptor antagonist, improves their clinical symptoms with fewer side effects. We hypothesized that patients with schizophrenia treated with amisulpride and aripiprazole show increased working memory and glucose metabolism compared with those treated with cognitive behavioral therapy (CBT) and aripiprazole instead.

Methods

Sixteen patients with schizophrenia (eight in the amisulpride group [aripiprazole+amisulpride] and eight in the CBT group [aripiprazole+CBT]) and 15 age- and sex-matched healthy control subjects were recruited for a 12-week-long prospective trial. An [18F]-fluorodeoxyglucose-positron emission tomography/computerized tomography scanner was used to acquire the images.

Results

After 12 weeks of treatment, the amisulpride group showed greater improvement in the Letter-Number Span scores than the CBT group. Additionally, although brain metabolism in the left middle frontal gyrus, left occipital lingual gyrus, and right inferior parietal lobe was increased in all patients with schizophrenia, the amisulpride group exhibited a greater increase in metabolism in both the right superior frontal gyrus and right frontal precentral gyrus than the CBT group.

Conclusion

This study suggests that a small dose of amisulpride improves the general psychopathology, working memory performance, and brain glucose metabolism of patients with schizophrenia treated with aripiprazole.

Impaired prefrontal functional connectivity associated with working memory task performance and disorganization despite intact activations in schizophrenia

Working memory (WM) deficits are key features of schizophrenia and are associated with significant functional impairment. The precise mechanisms of WM and their relationship between WM deficits with other clinical symptoms of schizophrenia remain unclear. Contemporary models propose that WM requires synchronous activity across brain regions within a distributed network, including lateral prefrontal cortex (PFC) and task-relevant posterior sensory cortical regions. This suggests that WM deficits in patients may be due to PFC functional connectivity (FC) impairments rather than activation impairments per se. We tested this hypothesis by measuring the magnitude of FC between lateral PFC and visual cortex and univariate activations within these regions during visual WM. We found decreased FC in patients compared to healthy subjects in the context of similar levels of univariate activity. Furthermore, this decreased FC was associated with task performance and clinical symptomatology in patients. The magnitude of FC, particularly during the delay period, was positively correlated with WM task accuracy, while FC during cue was inversely correlated with severity of disorganization. Taken together, these results suggest that impairment in lateral PFC FC is a key aspect of information processing impairment in patients with schizophrenia, and may be a sensitive index of altered neurophysiology.

Schizophrenia-related abnormalities in the triple network: a meta-analysis of working memory studies

Previous meta-analyses found abnormal brain activations in schizophrenia patients compared with normal controls when performing working memory tasks. Although most studies focused on dysfunction of the working memory activation network in schizophrenia patients, deactivation abnormalities of the working memory in the default mode network have also been reported in schizophrenia but have received less attention. Our goal was to discover whether deactivation abnormalities can also be consistently found in schizophrenia during working memory tasks and, further, to consider both activation and deactivation abnormalities. Fifty-two English language peer-reviewed studies were included in this meta-analysis. Compared with normal controls, the schizophrenia patients showed activation dysfunction of the bilateral dorsolateral prefrontal cortex and posterior parietal cortex as well as the anterior insula, anterior cingulate cortex, and supplementary motor area, which are core nodes of the central executive and salience network. In addition to dysfunction of the activation networks, the patients showed deactivation abnormalities in the ventral medial prefrontal cortex and posterior cingulate cortex, which are core nodes of the default mode network. These results suggest that both activation and deactivation abnormalities exist in schizophrenia patients and that these abnormalities should both be considered when investigating the pathophysiological mechanism of schizophrenia.

Clinical utility of the dual n-back task in schizophrenia: A functional imaging approach

The neural correlate of working memory (WM) impairment in schizophrenia is key to the understanding of the cognitive deficits observed in this disorder. We sought to determine the clinical validity of the dual version n-back paradigm in patients with schizophrenia, and whether schizophrenia patients exhibit altered brain activation patterns compared with healthy controls in this dual version WM measure using functional magnetic resonance imaging. Patients with schizophrenia (n = 20) and healthy controls (n = 24) performed the dual n-back task that consists of both visuospatial and auditory-verbal n-back streams, in which participants were required to monitor and update the contents from these two different inputs simultaneously. Significant positive correlations were found between performance in the dual 2-back condition and another measure of WM capacity and IQ estimates. Moreover, hypoactivation was observed at the right middle frontal gyrus and the posterior parietal regions in schizophrenia participants compared with healthy controls. The right hippocampus was less deactivated in schizophrenia patients compared with healthy controls. Our results support the clinical utility of the dual n-back task in schizophrenia and may have implications for the development of specific cognitive training targeting these impaired neural substrates in relation to WM in patients with schizophrenia.

Cognitive control network dysconnectivity and response to antipsychotic treatment in schizophrenia

To better understand cognitive control impairment in schizophrenia, it is vital to determine the extent of dysfunctional connectivity in the associated fronto-striatal brain network, with a focus on the connections with the anterior cingulate cortex (ACC), prior to the potential confounding effect of medication. It is also essential to determine the effects following antipsychotic medication and the relationship of those effects on psychosis improvement. Twenty-two patients with schizophrenia, initially unmedicated and after a 6-week course of risperidone, and 20 matched healthy controls (HC) performed a fMRI task twice, six weeks apart. We investigated group and longitudinal differences in ACC-related functional connectivity during performance of a Stroop color task as well as connectivity patterns associated with improvement in psychosis symptoms. Unmedicated patients with schizophrenia showed greater functional connectivity between ACC and bilateral caudate and midbrain and lower connectivity with left putamen compared to healthy controls. At baseline, greater functional connectivity between ACC and bilateral putamen predicted subsequent better treatment response. Change in functional connectivity between ACC and left putamen positively correlated with better treatment response. These results suggest that patterns of functional connectivity in fronto-striatal networks can be utilized to predict potential response to antipsychotic medication. Prior to treatment, brain function may be structured with a predisposition that favors or not treatment response.

Novelty modulates human striatal activation and prefrontal-striatal effective connectivity during working memory encoding

The functional role of the basal ganglia (BG) in the gating of suitable motor responses to the cortex is well established. Growing evidence supports an analogous role of the BG during working memory encoding, a task phase in which the "input-gating" of relevant materials (or filtering of irrelevant information) is an important mechanism supporting cognitive capacity and the updating of working memory buffers. One important aspect of stimulus relevance is the novelty of working memory items, a quality that is understudied with respect to its effects on corticostriatal function and connectivity. To this end, we used functional magnetic resonance imaging (fMRI) in 74 healthy volunteers performing an established Sternberg working memory task with different task phases (encoding vs. retrieval) and degrees of stimulus familiarity (novel vs. previously trained). Activation analyses demonstrated a highly significant engagement of the anterior striatum, in particular during the encoding of novel working memory items. Dynamic causal modeling (DCM) of corticostriatal circuit connectivity identified a selective positive modulatory influence of novelty encoding on the connection from the dorsolateral prefrontal cortex (DLPFC) to the anterior striatum. These data extend prior research by further underscoring the relevance of the BG for human cognitive function and provide a mechanistic account of the DLPFC as a plausible top-down regulatory element of striatal function that may facilitate the "input-gating" of novel working memory materials.

Evaluation of fronto-striatal networks during cognitive control in unmedicated patients with schizophrenia and the effect of antipsychotic medication

To understand the mechanism of cognitive control dysfunction in schizophrenia, it is critical to characterize brain function without the confounding effect of medication. It is also important to establish the extent to which antipsychotic medication restores brain function and whether those changes are related to psychosis improvement. Twenty-two patients with schizophrenia, initially unmedicated and after a 6-week course of risperidone, and 20 healthy controls (HC) studied twice, 6 weeks apart, performed an fMRI task. We examined group and longitudinal differences in anterior cingulate cortex (ACC), striatum, and midbrain functional activity during performance of a Stroop color task as well as activity patterns associated with improvement in psychosis symptoms. Unmedicated patients showed reduced functional activity in the ACC, striatum, and midbrain compared to HC. Post hoc contrasts from significant group-by-time interactions indicated that, in patients, drug administration was associated with both activity increases and decreases. In unmedicated patients, greater baseline functional activity in the striatum and midbrain predicted subsequent better treatment response. Greater changes in functional activity in ACC and ventral putamen over the course of 6 weeks positively correlated with better treatment response. Unmedicated patients show reduced activity in brain networks pivotal for cognitive control and medication is associated with functional changes in these regions. These results suggest a mechanism by which antipsychotic medication has a beneficial effect on cognition. Our results also support the notion that treatment response is determined by a combination of the baseline pattern of brain function and by the pharmacological modulation of these regions.

Reduced Functional Brain Activation and Connectivity During a Working Memory Task in Childhood-Onset Schizophrenia

OBJECTIVE

Working memory (WM) deficits are consistently reported in schizophrenia and are related to poor functional outcomes. Functional magnetic resonance imaging studies of adult-onset schizophrenia have reported decreased functional activations and connectivity in the WM network, but no prior functional magnetic resonance imaging study has examined WM in childhood-onset schizophrenia (COS). The aim of this study was to examine the neural correlates of WM in COS.

METHOD

Adult patients with COS (n = 32, 21.3 ± 1.1 years), nonpsychotic siblings of patients with COS (n = 30, 19.4 ± 0.8 years), and healthy controls (n = 39, 20.0 ± 0.7 years) completed 1- and 2-back WM tasks during 3-T functional magnetic resonance imaging. Functional activation and connectivity analyses were conducted. A separate group of 23 younger patients with COS (17.9 ± 7.4 years) could not perform the tasks after twice completing a standard training and are not included in this report.

RESULTS

Patients with COS who were included scored significantly lower than controls on all tasks (p < .001). Patients with COS showed significantly lower activations in the dorsolateral prefrontal cortices, posterior parietal cortices, cerebellum, and caudate and decreased frontoparietal and corticostriatal functional connectivity compared with controls (p < .05, corrected). Siblings had functional activations and connectivity intermediate between those of patients and controls in a similar set of regions (p < .05, corrected). In patients, functional connectivity strength in the left frontoparietal network correlated positively with accuracy scores during the 1-back task (p = .0023, corrected).

CONCLUSION

Decreased functional activation and connectivity in the WM network in COS supports pathophysiologic continuity with adult-onset schizophrenia. The low participation rate and accuracy of the patients highlights the disease severity of COS. Hypo-activations and hypo-connectivity were shared by siblings of patients with COS, suggesting COS as a potential endophenotype.

CLINICAL TRIAL REGISTRATION INFORMATION

Evaluating Genetic Risk Factors for Childhood-Onset Schizophrenia; http://ClinicalTrials.gov;NCT00001198.

Translational Significance of Selective Estrogen Receptor Modulators in Psychiatric Disorders

Accumulating data from various clinical trial studies suggests that adjuvant therapy with ovarian hormones (estrogens) could be effective in reducing cognitive deficit and psychopathological symptoms in women with psychiatric disorders. However, estrogen therapy poses serious limitations and health issues including feminization in men and increased risks of thromboembolism, hot flashes, breast hyperplasia, and endometrium hyperplasia when used for longer duration in older women (aged ≥ 60 years) or in women who have genetic predispositions. On the other hand, selective estrogen receptor modulators (SERMs), which may (or may not) carry some risks of hot flashes, thromboembolism, breast hyperplasia, and endometrial hyperplasia, are generally devoid of feminization effect. In clinical trial studies, adjuvant therapy with tamoxifen, a triphenylethylene class of SERM, has been found to reduce the frequency of manic episodes in patients with bipolar disorder, whereas addition of raloxifene, a benzothiophene class of SERM, to regular doses of antipsychotic drugs has been found to reduce cognitive deficit and psychological symptoms in men and women with schizophrenia, including women with treatment refractory psychosis. These outcomes together with potent neurocognitive, neuroprotective, and cardiometabolic properties suggest that SERMs could be the potential targets for designing effective and safer therapies for psychiatric disorders.

Verbal working memory and functional large-scale networks in schizophrenia

The aim of this study was to test whether bilinear and nonlinear effective connectivity (EC) measures of working memory fMRI data can differentiate between patients with schizophrenia (SZ) and healthy controls (HC). We applied bilinear and nonlinear Dynamic Causal Modeling (DCM) for the analysis of verbal working memory in 16 SZ and 21 HC. The connection strengths with nonlinear modulation between the dorsolateral prefrontal cortex (DLPFC) and the ventral tegmental area/substantia nigra (VTA/SN) were evaluated. We used Bayesian Model Selection at the group and family levels to compare the optimal bilinear and nonlinear models. Bayesian Model Averaging was used to assess the connection strengths with nonlinear modulation. The DCM analyses revealed that SZ and HC used different bilinear networks despite comparable behavioral performance. In addition, the connection strengths with nonlinear modulation between the DLPFC and the VTA/SN area showed differences between SZ and HC. The adoption of different functional networks in SZ and HC indicated neurobiological alterations underlying working memory performance, including different connection strengths with nonlinear modulation between the DLPFC and the VTA/SN area. These novel findings may increase our understanding of connectivity in working memory in schizophrenia.

Functional dysconnectivity of the limbic loop of frontostriatal circuits in first-episode, treatment-naive schizophrenia

Frontostriatal circuits dysfunction has been implicated in the etiology and psychopathology of patients with schizophrenia (SZ). However, few studies have investigated SZ-related functional connectivity (FC) alterations in discrete frontostriatal circuits and their relationship with pathopsychology in first-episode schizophrenia (FESZ). The goal of this study was to identify dysfunctions in discrete frontostriatal circuits that are associated with key features of FESZ. To this end, a case-control, cross-sectional study was conducted, wherein resting-state (RS) functional magnetic resonance (fMRI) data were collected from 37 treatment-naïve FESZ patients and 29 healthy control (HC) subjects. Seed-based FC analyses were performed by placing six bilateral pairs of seeds within a priori defined subdivisions of the striatum. We observed significantly decreased FC for the FESZ group relative to the HC group [p < .05, family-wise error (FWE)-corrected] in the limbic loop, but not in the sensorimotor or associative loops, of frontostriatal circuitry. Moreover, bilaterally decreased inferior ventral striatum/nucleus accumbens (VSi)-dorsal anterior cingulate cortex (dACC) FC within the limbic loop correlated inversely with overall FESZ symptom severity and the disorganization factor score of PANSS. These findings provide new insight into the role of frontostriatal limbic loop hypoconnectivity in early-stage schizophrenia pathology and suggest potential novel therapeutic targets.

Effects of gratitude meditation on neural network functional connectivity and brain-heart coupling

A sense of gratitude is a powerful and positive experience that can promote a happier life, whereas resentment is associated with life dissatisfaction. To explore the effects of gratitude and resentment on mental well-being, we acquired functional magnetic resonance imaging and heart rate (HR) data before, during, and after the gratitude and resentment interventions. Functional connectivity (FC) analysis was conducted to identify the modulatory effects of gratitude on the default mode, emotion, and reward-motivation networks. The average HR was significantly lower during the gratitude intervention than during the resentment intervention. Temporostriatal FC showed a positive correlation with HR during the gratitude intervention, but not during the resentment intervention. Temporostriatal resting-state FC was significantly decreased after the gratitude intervention compared to the resentment intervention. After the gratitude intervention, resting-state FC of the amygdala with the right dorsomedial prefrontal cortex and left dorsal anterior cingulate cortex were positively correlated with anxiety scale and depression scale, respectively. Taken together, our findings shed light on the effect of gratitude meditation on an individual’s mental well-being, and indicate that it may be a means of improving both emotion regulation and self-motivation by modulating resting-state FC in emotion and motivation-related brain regions.

Functional Connectivity of Cognitive Brain Networks in Schizophrenia during a Working Memory Task

Task-based connectivity studies facilitate the understanding of how the brain functions during cognition, which is commonly impaired in schizophrenia (SZ). Our aim was to investigate functional connectivity during a working memory task in SZ. We hypothesized that the task-negative (default mode) network and the cognitive control (frontoparietal) network would show dysconnectivity. Twenty-five SZ patient and 31 healthy control scans were collected using the customized 3T Siemens Skyra MRI scanner, previously used to collect data for the Human Connectome Project. Blood oxygen level dependent signal during the 0-back and 2-back conditions were extracted within a network-based parcelation scheme. Average functional connectivity was assessed within five brain networks: frontoparietal (FPN), default mode (DMN), cingulo-opercular (CON), dorsal attention (DAN), and ventral attention network; as well as between the DMN or FPN and other networks. For within-FPN connectivity, there was a significant interaction between n-back condition and group (p = 0.015), with decreased connectivity at 0-back in SZ subjects compared to controls. FPN-to-DMN connectivity also showed a significant condition × group effect (p = 0.003), with decreased connectivity at 0-back in SZ. Across groups, connectivity within the CON and DAN were increased during the 2-back condition, while DMN connectivity with either CON or DAN were decreased during the 2-back condition. Our findings support the role of the FPN, CON, and DAN in working memory and indicate that the pattern of FPN functional connectivity differs between SZ patients and control subjects during the course of a working memory task.

Transdiagnostic neural markers of emotion-cognition interaction in psychotic disorders

Deficits in working memory (WM) and emotion processing are prominent impairments in psychotic disorders, and have been linked to reduced quality of life and real-world functioning. Translation of knowledge regarding the neural circuitry implementing these deficits into improved diagnosis and targeted treatments has been slow, possibly because of categorical definitions of disorders. Using the dimensional Research Domain Criteria (RDoC) framework, we investigated the clinical and practical utility of transdiagnostic behavioral and neural measures of emotion-related WM disruption across psychotic disorders. Behavioral and functional MRI data were recorded while 53 participants with psychotic disorders and 29 participants with no history of psychosis performed a modified n-back task with fear and neutral distractors. Hierarchical regression analyses showed that psychotic symptoms entered after diagnosis accounted for unique variance in fear versus neutral accuracy and activation in the ventrolateral, dorsolateral, and dorsomedial prefrontal cortex, but diagnostic group entered after psychotic symptoms did not. These results remained even after controlling for negative symptoms, disorganized symptoms, and dysphoria. Finally, worse accuracy and greater prefrontal activity were associated with poorer social functioning and unemployment across diagnostic groups. Present results support the transdiagnostic nature of behavioral and neuroimaging measures of emotion-related WM disruption as they relate to psychotic symptoms, irrespective of diagnosis. They also provide support for the practical utility of these markers in explaining real-world functioning. Overall, these results elucidate key aspects of the RDoC construct of WM maintenance by clarifying its transdiagnostic importance and clinical utility in psychotic disorders. (PsycINFO Database Record

Dopamine-Related Disruption of Functional Topography of Striatal Connections in Unmedicated Patients With Schizophrenia

IMPORTANCE

Despite the well-established role of striatal dopamine in psychosis, current views generally agree that cortical dysfunction is likely necessary for the emergence of psychotic symptoms. The topographic organization of striatal-cortical connections is central to gating and integration of higher-order information, so a disruption of such topography via dysregulated dopamine could lead to cortical dysfunction in schizophrenia. However, this hypothesis remains to be tested using multivariate methods ascertaining the global pattern of striatal connectivity and without the confounding effects of antidopaminergic medication.

OBJECTIVES

To examine whether the pattern of brain connectivity across striatal subregions is abnormal in unmedicated patients with schizophrenia and whether this abnormality relates to psychotic symptoms and extrastriatal dopaminergic transmission.

DESIGN, SETTING, AND PARTICIPANTS

In this multimodal, case-control study, we obtained resting-state functional magnetic resonance imaging data from 18 unmedicated patients with schizophrenia and 24 matched healthy controls from the New York State Psychiatric Institute. A subset of these (12 and 17, respectively) underwent positron emission tomography with the dopamine D2 receptor radiotracer carbon 11-labeled FLB457 before and after amphetamine administration. Data were acquired between June 16, 2011, and February 25, 2014. Data analysis was performed from September 1, 2014, to January 11, 2016.

MAIN OUTCOMES AND MEASURES

Group differences in the striatal connectivity pattern (assessed via multivariable logistic regression) across striatal subregions, the association between the multivariate striatal connectivity pattern and extrastriatal baseline D2 receptor binding potential and its change after amphetamine administration, and the association between the multivariate connectivity pattern and the severity of positive symptoms evaluated with the Positive and Negative Syndrome Scale.

RESULTS

Of the patients with schizophrenia (mean [SEM] age, 35.6 [11.8] years), 9 (50%) were male and 9 (50%) were female. Of the controls (mean [SEM] age, 33.7 [8.8] years), 10 (42%) were male and 14 (58%) were female. Patients had an abnormal pattern of striatal connectivity, which included abnormal caudate connections with a distributed set of associative cortex regions (χ229 = 53.55, P = .004). In patients, more deviation from the multivariate pattern of striatal connectivity found in controls correlated specifically with more severe positive symptoms (ρ = -0.77, P = .002). Striatal connectivity also correlated with baseline binding potential across cortical and extrastriatal subcortical regions (t25 = 3.01, P = .01, Bonferroni corrected) but not with its change after amphetamine administration.

CONCLUSIONS AND RELEVANCE

Using a multimodal, circuit-level interrogation of striatal-cortical connections, it was demonstrated that the functional topography of these connections is globally disrupted in unmedicated patients with schizophrenia. These findings suggest that striatal-cortical dysconnectivity may underlie the effects of dopamine dysregulation on the pathophysiologic mechanism of psychotic symptoms.

Reduction of Pavlovian Bias in Schizophrenia: Enhanced Effects in Clozapine-Administered Patients

The negative symptoms of schizophrenia (SZ) are associated with a pattern of reinforcement learning (RL) deficits likely related to degraded representations of reward values. However, the RL tasks used to date have required active responses to both reward and punishing stimuli. Pavlovian biases have been shown to affect performance on these tasks through invigoration of action to reward and inhibition of action to punishment, and may be partially responsible for the effects found in patients. Forty-five patients with schizophrenia and 30 demographically-matched controls completed a four-stimulus reinforcement learning task that crossed action ("Go" or "NoGo") and the valence of the optimal outcome (reward or punishment-avoidance), such that all combinations of action and outcome valence were tested. Behaviour was modelled using a six-parameter RL model and EEG was simultaneously recorded. Patients demonstrated a reduction in Pavlovian performance bias that was evident in a reduced Go bias across the full group. In a subset of patients administered clozapine, the reduction in Pavlovian bias was enhanced. The reduction in Pavlovian bias in SZ patients was accompanied by feedback processing differences at the time of the P3a component. The reduced Pavlovian bias in patients is suggested to be due to reduced fidelity in the communication between striatal regions and frontal cortex. It may also partially account for previous findings of poorer "Go-learning" in schizophrenia where "Go" responses or Pavlovian consistent responses are required for optimal performance. An attenuated P3a component dynamic in patients is consistent with a view that deficits in operant learning are due to impairments in adaptively using feedback to update representations of stimulus value.

Dysfunctional Striatal Systems in Treatment-Resistant Schizophrenia

The prevalence of treatment-resistant schizophrenia points to a discrete illness subtype, but to date its pathophysiologic characteristics are undetermined. Information transfer from ventral to dorsal striatum depends on both striato-cortico-striatal and striato-nigro-striatal subcircuits, yet although the functional integrity of the former appears to track improvement of positive symptoms of schizophrenia, the latter have received little experimental attention in relation to the illness. Here, in a sample of individuals with schizophrenia stratified by treatment resistance and matched controls, functional pathways involving four foci along the striatal axis were assessed to test the hypothesis that treatment-resistant and non-refractory patients would exhibit contrasting patterns of resting striatal connectivity. Compared with non-refractory patients, treatment-resistant individuals exhibited reduced connectivity between ventral striatum and substantia nigra. Furthermore, disturbance to corticostriatal connectivity was more pervasive in treatment-resistant individuals. The occurrence of a more distributed pattern of abnormality may contribute to the failure of medication to treat symptoms in these individuals. This work strongly supports the notion of pathophysiologic divergence between individuals with schizophrenia classified by treatment-resistance criteria.