Resting-state functional connectivity of the nucleus accumbens in auditory and visual hallucinations in schizophrenia

Short-term antipsychotic treatment reduces functional connectivity of the striatum in first-episode drug-naïve early-onset schizophrenia

BACKGROUND

The striatum is thought to play a critical role in the pathophysiology and antipsychotic treatment of schizophrenia. Previous studies have revealed abnormal functional connectivity (FC) of the striatum in early-onset schizophrenia (EOS) patients. However, no prior studies have examined post-treatment changes of striatal FC in EOS patients.

METHODS

We recruited 49 first-episode drug-naïve EOS patients to have resting-state functional magnetic resonance imaging scans at baseline and after 8 weeks of treatment with antipsychotics, along with baseline scanning of 34 healthy controls (HCs) for comparison purposes. We examined the FC values between each seed in striatal subregion and the rest of the brain. The Positive and Negative Syndrome Scale (PANSS) was applied to measure psychiatric symptoms in patients.

RESULTS

Compared with HCs at baseline, EOS patients exhibited weaker FC of striatal subregions with several brain regions of the salience network and default mode network. Meanwhile, FC between the dorsal caudal putamen (DCP) and left supplementary motor area, as well as between the DCP and right postcentral gyrus, was negatively correlated with PANSS negative scores. Furthermore, after 8 weeks of treatment, EOS patients showed decreased FC between subregions of the putamen and the triangular part of inferior frontal gyrus, middle frontal gyrus, supramarginal gyrus and inferior parietal lobule.

CONCLUSIONS

Decreased striatal FC is evident, even in the early stages of schizophrenia, and enhance our understanding of the neurodevelopmental abnormalities in schizophrenia. The findings also demonstrate that reduced striatal FC occurs after antipsychotic therapy, indicating that antipsychotic effects need to be accounted for when considering striatal FC abnormalities in schizophrenia.

Hypoactivation of the language network during auditory imagery contributes to hallucinations in Schizophrenia

Auditory verbal hallucinations (AVHs) involve perceptions, often voices, in the absence of external stimuli, and rank among the most common symptoms of schizophrenia. Metrical stress evaluation requires determination of the stronger syllable in words, and therefore requires auditory imagery, of interest for investigation of hallucinations in schizophrenia. The current functional magnetic resonance imaging study provides an updated whole-brain network analysis of a previously published study on metrical stress, which showed reduced directed connections between Broca's and Wernicke's regions of interest (ROIs) for hallucinations. Three functional brain networks were extracted, with the language network (LN) showing an earlier and shallower blood-oxygen-level dependent (BOLD) response for hallucinating patients, in the auditory imagery condition only (the reduced activation for hallucinations observed in the original ROI-based results were not specific to the imagery condition). This suggests that hypoactivation of the LN during internal auditory imagery may contribute to the propensity to hallucinate. This accords with cognitive accounts holding that an impaired balance between internal and external linguistic processes (underactivity in networks involved in internal auditory imagery and overactivity in networks involved in speech perception) contributes to our understanding of the biological underpinnings of hallucinations.

Abnormal effective connectivity of reward network in first-episode schizophrenia with auditory verbal hallucinations

OBJECTIVE

Auditory verbal hallucinations (AVHs) in schizophrenia is proved to be associated with dysfunction of mesolimbic-cortical circuits, especially during abnormal salient and internal verbal resource monitoring processing procedures. However, the information flow among areas involved in coordinated interaction implicated the pathophysiology of AVHs remains unclear.

METHODS

We used spectral dynamic causal modeling (DCM) to quantify connections among eight critical hubs of reward network in 86 first-episode drug-naïve schizophrenia patients with AVHs (AVH), 93 patients without AVHs (NAVH), and 88 matched normal controls (NC) using resting-state functional magnetic resonance imaging. Group-level connection coefficients, between-group differences and correlation analysis between image measures and symptoms were performed.

RESULT

DCM revealed weaker effective connectivity (EC) from right ventral striatum (RVS) to ventral tegmental area (VTA) in AVH compared to NAVH. AVH showed stronger EC from left anterior insula (AI) to RVS, stronger EC from RVS to anterior cingulate cortex (ACC), and stronger EC from VTA to posterior cingulate cortex (PCC) compared to NC. The correlation analysis results were mostly visible in the negative correlation between EC from right AI to ACC and positive sub-score, P1 sub-score, and P3 sub-score of PNASS in group-level.

CONCLUSION

These findings suggest that neural causal interactions between the reward network associated with AVHs are disrupted, expanding the evidence for potential neurobiological mechanisms of AVHs. Particularly, dopamine-dependent salience attribution and top-down monitoring impairments and compensatory effects of enhanced excitatory afferents to ACC, which may provide evidence for a therapeutic target based on direct in vivo of AVHs in schizophrenia.

ROI-based analysis of diffusion indices in healthy subjects and subjects with deficit or non-deficit syndrome schizophrenia

We analyzed DTI data involving 22 healthy subjects (HC), 15 patients with deficit syndrome schizophrenia (DSZ), and 25 patients with non-deficit syndrome schizophrenia (NDSZ). We used a 1.5-T MRI scanner to collect diffusion-weighted images and T1 images, which were employed to correct distortions and deformations within the diffusion-weighted images. For 156 regions of interest (ROI), we calculated the average fractional anisotropy (FA), mean diffusion (MD), and radial diffusion (RD). Each ROI underwent a group-wise comparison using permutation F-test, followed by post hoc pairwise comparisons with Bonferroni correction. In general, we observed lower FA in both schizophrenia groups compared to HC (i.e., HC>(DSZ=NDSZ)), while MD and RD showed the opposite pattern. Notably, specific ROIs with reduced FA in schizophrenia patients included bilateral nucleus accumbens, left fusiform area, brain stem, anterior corpus callosum, left rostral and caudal anterior cingulate, right posterior cingulate, left thalamus, left hippocampus, left inferior temporal cortex, right superior temporal cortex, left pars triangularis and right lingual gyrus. Significantly, the right cuneus exhibited lower FA in the DSZ group compared to other groups ((HC=NDSZ)>DSZ), without affecting MD and RD. These results indicate that compromised neural integrity in the cuneus may contribute to the pathophysiological distinctions between DSZ and NDSZ.

Reduced neural connectivity in the caudate anterior head predicts hallucination severity in schizophrenia

BACKGROUND

Caudate functional abnormalities have been identified as one critical neural substrate underlying sensory gating impairments that lead to auditory phantom hallucinations in both patients with schizophrenia (SZ) and tinnitus, characterized by the perception of internally generated sounds in the absence of external environmental auditory stimuli. In this study, we tested the hypothesis as to whether functional connectivity abnormalities in distinct caudate subdivisions implicated in sensory gating and auditory phantom percepts in tinnitus, which are currently being localized for neuromodulation targeting using deep brain stimulation techniques, would be associated with auditory phantom hallucination severity in SZ.

METHODS

Twenty five SZ and twenty eight demographically-matched healthy control (HC) participants, completed this fMRI resting-state study and clinical assessments.

RESULTS

Between-group seed-to-voxel analyses revealed only one region, the caudate anterior head, which showed reduced functional connectivity with the thalamus that survived whole-brain multiple comparison corrections. Importantly, connectivity between the caudate anterior head with thalamus negatively correlated with hallucination severity.

CONCLUSIONS

In the present study, we deliver the first evidence of caudate subdivision specificity for the neural pathophysiology underlying hallucinations in schizophrenia within a sensory gating framework that has been developed for auditory phantoms in patients with tinnitus. Our findings provide transdiagnostic convergent evidence for the role of the caudate in the gating of auditory phantom hallucinations, observed across patients with SZ and tinnitus by specifying the anterior caudate division is key to mediation of hallucinations, and creating a path towards personalized treatment approaches to arrest auditory phantom hallucinations from reaching perceptual awareness.

Learning without contingencies: A loss of synergy between memory and reward circuits in schizophrenia

Motivational deficits in schizophrenia may interact with foundational cognitive processes including learning and memory to induce impaired cognitive proficiency. If such a loss of synergy exists, it is likely to be underpinned by a loss of synchrony between the brains learning and reward sub-networks. Moreover, this loss should be observed even during tasks devoid of explicit reward contingencies given that such tasks are better models of real world performance than those with artificial contingencies. Here we applied undirected functional connectivity (uFC) analyses to fMRI data acquired while participants engaged in an associative learning task without contingencies or feedback. uFC was estimated and inter-group differences (between schizophrenia patients and controls, n = 54 total, n = 28 patients) were assessed within and between reward (VTA and NAcc) and learning/memory (Basal Ganglia, DPFC, Hippocampus, Parahippocampus, Occipital Lobe) sub-networks. The task paradigm itself alternated between Encoding, Consolidation, and Retrieval conditions, and uFC differences were quantified for each of the conditions. Significantly reduced uFC dominated the connectivity profiles of patients across all conditions. More pertinent to our motivations, these reductions were observed within and across classes of sub-networks (reward-related and learning/memory related). We suggest that disrupted functional connectivity between reward and learning sub-networks may drive many of the performance deficits that characterize schizophrenia. Thus, cognitive deficits in schizophrenia may in fact be underpinned by a loss of synergy between reward-sensitivity and cognitive processes.

Modulation of dopamine from ventral tegmental area neurons by the LC-REM-OFF and PPT-REM-ON neurons in REMS regulation in freely moving rats

The role of dopamine (DA)-ergic neurons in ventral tegmental area (VTA) in schizophrenia, depression, hallucinations have been extensively studied. Rapid eye movement sleep (REMS), the closest objective correlate of dream and hallucination, is disrupted during these psychological dysfunctions; however, it was unknown if there is any common neuronal substrate for their regulation. Interactions among locus coeruleus (LC) REM-OFF and pedunculopontine tegmentum (PPT) REM-ON neurons have been reported to regulate REMS in health and diseases. Recently we have reported that PPT neurons modulate VTA and REMS. However, although VTA-DA neurons receive projections from LC and PPT, their role in REMS regulation was unclear. We proposed that the LC and PPT might intermittently modulate VTA-DA neurons and modulate REMS. Male Wistar rats were surgically prepared and electrophysiological wakefulness-sleep-REMS recorded in chronic freely moving condition. We employed RNAi induced downregulation of tyrosine hydroxylase (TH) to evaluate the role of VTA-DA in regulating REMS. We observed that TH-knockdown in VTA decreased REMS in experimental rats, which returned to baseline upon PPT stimulation. Thus, VTA-DA neurons are activated by the REM-ON neurons to modulate REMS, the closest objectively recordable correlate of dreams. In these animals, LC stimulation altered Non-REMS and waking. Based on the findings we have discussed the role of VTA neurochemical circuitry in REMS regulation and their possible implications with REMS-associated dreaming and hallucination in health and diseases.

Neurexin1α knockout rats display oscillatory abnormalities and sensory processing deficits back-translating key endophenotypes of psychiatric disorders

Neurexins are presynaptic transmembrane proteins crucial for synapse development and organization. Deletion and missense mutations in all three Neurexin genes have been identified in psychiatric disorders, with mutations in the NRXN1 gene most strongly linked to schizophrenia (SZ) and autism spectrum disorder (ASD). While the consequences of NRXN1 deletion have been extensively studied on the synaptic and behavioral levels, circuit endophenotypes that translate to the human condition have not been characterized yet. Therefore, we investigated the electrophysiology of cortico-striatal-thalamic circuits in Nrxn1α^-/- rats and wildtype littermates focusing on a set of translational readouts, including spontaneous oscillatory activity, auditory-evoked oscillations and potentials, as well as mismatch negativity-like (MMN) responses and responses to social stimuli. On the behavioral level Nrxn1α^-/- rats showed locomotor hyperactivity. In vivo freely moving electrophysiology revealed pronounced increases of spontaneous oscillatory power within the gamma band in all studied brain areas and elevation of gamma coherence in cortico-striatal and thalamocortical circuits of Nrxn1α^-/- rats. In contrast, auditory-evoked oscillations driven by chirp-modulated tones showed reduced power in cortical areas confined to slower oscillations. Finally, Nrxn1α^-/- rats exhibited altered auditory evoked-potentials and profound deficits in MMN-like responses, explained by reduced prediction error. Despite deficits for auditory stimuli, responses to social stimuli appeared intact. A central hypothesis for psychiatric and neurodevelopmental disorders is that a disbalance of excitation-to-inhibition is underlying oscillatory and sensory deficits. In a first attempt to explore the impact of inhibitory circuit modulation, we assessed the effects of enhancing tonic inhibition via δ-containing GABA_A receptors (using Gaboxadol) on endophenotypes possibly associated with network hyperexcitability. Pharmacological experiments applying Gaboxadol showed genotype-specific differences, but failed to normalize oscillatory or sensory processing abnormalities. In conclusion, our study revealed endophenotypes in Nrxn1α^-/- rats that could be used as translational biomarkers for drug development in psychiatric disorders.

From hallucinations to synaesthesia: A circular inference account of unimodal and multimodal erroneous percepts in clinical and drug-induced psychosis

Psychedelics distort perception and induce visual and multimodal hallucinations as well as synaesthesia. This is in contradiction with the high prevalence of distressing voices in schizophrenia. Here we introduce a unifying account of unimodal and multimodal erroneous percepts based on circular inference. We show that amplification of top-down predictions (descending loops) leads to an excessive reliance on priors and aberrant levels of integration of the sensory representations, resulting in crossmodal percepts and stronger illusions. By contrast, amplification of bottom-up information (ascending loops) results in overinterpretation of unreliable sensory inputs and high levels of segregation between sensory modalities, bringing about unimodal hallucinations and reduced vulnerability to illusions. We delineate a canonical microcircuit in which layer-specific inhibition controls the propagation of information across hierarchical levels: inhibitory interneurons in the deep layers exert control over priors, removing descending loops. Conversely, inhibition in the supragranular layers counterbalances the effects of the ascending loops. Overall, we put forward a multiscale and transnosographic account of erroneous percepts with important theoretical, conceptual and clinical implications.

Altered brain structural and functional connectivity in schizotypy

BACKGROUND

Schizotypy refers to schizophrenia-like traits below the clinical threshold in the general population. The pathological development of schizophrenia has been postulated to evolve from the initial coexistence of 'brain disconnection' and 'brain connectivity compensation' to 'brain connectivity decompensation'.

METHODS

In this study, we examined the brain connectivity changes associated with schizotypy by combining brain white matter structural connectivity, static and dynamic functional connectivity analysis of diffusion tensor imaging data and resting-state functional magnetic resonance imaging data. A total of 87 participants with a high level of schizotypal traits and 122 control participants completed the experiment. Group differences in whole-brain white matter structural connectivity probability, static mean functional connectivity strength, dynamic functional connectivity variability and stability among 264 brain sub-regions of interests were investigated.

RESULTS

We found that individuals with high schizotypy exhibited increased structural connectivity probability within the task control network and within the default mode network; increased variability and decreased stability of functional connectivity within the default mode network and between the auditory network and the subcortical network; and decreased static mean functional connectivity strength mainly associated with the sensorimotor network, the default mode network and the task control network.

CONCLUSIONS

These findings highlight the specific changes in brain connectivity associated with schizotypy and indicate that both decompensatory and compensatory changes in structural connectivity within the default mode network and the task control network in the context of whole-brain functional disconnection may be an important neurobiological correlate in individuals with high schizotypy.

Enhanced Resting-State Functional Connectivity of the Nucleus Accumbens in First-Episode, Medication-Naïve Patients With Early Onset Schizophrenia

There is abundant evidence that early onset schizophrenia (EOS) is associated with abnormalities in widespread regions, including the cortical, striatal, and limbic areas. As a main component of the ventral striatum, the nucleus accumbens (NAc) is implicated in the pathology of schizophrenia. However, functional connection patterns of NAc in patients with schizophrenia, especially EOS, are seldom explored. A total of 78 first-episode, medication-naïve patients with EOS and 90 healthy controls were recruited in the present study, and resting-state, seed-based functional connectivity (FC) analyses were performed to investigate temporal correlations between NAc and the rest of the brain in the two groups. Additionally, correlation analyses were done between regions showing group differences in NAc functional integration and clinical features of EOS. Group comparison found enhanced FC of the NAc in the EOS group relative to the HCs with increased FC in the right superior temporal gyrus and left superior parietal gyrus with the left NAc region of interest (ROI) and elevated FC in left middle occipital gyrus with the right NAc ROI. No significant associations were found between FC strength and symptom severity as well as the age of the patients. Our findings reveal abnormally enhanced FC of the NAc with regions located in the temporal, parietal, and occipital areas, which were implicated in auditory/visual processing, sensorimotor integration, and cognitive functions. The results suggest disturbed relationships between regions subserving reward, salience processing, and regions subserving sensory processing as well as cognitive functions, which may deepen our understanding of the role of NAc in the pathology of EOS.

Modular-Level Functional Connectome Alterations in Individuals With Hallucinations Across the Psychosis Continuum

Functional connectome alterations, including modular network organization, have been related to the experience of hallucinations. It remains to be determined whether individuals with hallucinations across the psychosis continuum exhibit similar alterations in modular brain network organization. This study assessed functional connectivity matrices of 465 individuals with and without hallucinations, including patients with schizophrenia and bipolar disorder, nonclinical individuals with hallucinations, and healthy controls. Modular brain network organization was examined at different scales of network resolution, including (1) global modularity measured as Qmax and Normalised Mutual Information (NMI) scores, and (2) within- and between-module connectivity. Global modular organization was not significantly altered across groups. However, alterations in within- and between-module connectivity were observed for higher-order cognitive (e.g., central-executive salience, memory, default mode), and sensory modules in patients with schizophrenia and nonclinical individuals with hallucinations relative to controls. Dissimilar patterns of altered within- and between-module connectivity were found bipolar disorder patients with hallucinations relative to controls, including the visual, default mode, and memory network, while connectivity patterns between visual, salience, and cognitive control modules were unaltered. Bipolar disorder patients without hallucinations did not show significant alterations relative to controls. This study provides evidence for alterations in the modular organization of the functional connectome in individuals prone to hallucinations, with schizophrenia patients and nonclinical individuals showing similar alterations in sensory and higher-order cognitive modules. Other higher-order cognitive modules were found to relate to hallucinations in bipolar disorder patients, suggesting differential neural mechanisms may underlie hallucinations across the psychosis continuum.

Pedunculo-pontine tegmentum cholinergic REM-ON neurons modulate ventral tegmental neurons to modulate rapid eye movement sleep in rats

The interaction among the acetylcholine (ACh)-ergic REM-ON neurons in the pedunculo-pontine area (PPT), noradrenergic REM-OFF neurons in locus coeruleus (LC) and GABA-ergic neurons in the regulation of rapid eye movement sleep (REMS) have been studied in relative details; however, many questions including the role of dopamine (DA) remain unanswered. The ventral tegmental area (VTA) is rich in DA-ergic neurons, which have been implicated with schizophrenia and depression, when REMS is significantly affected. Also, some of the symptoms of REMS and these diseases are common. As the ACh-ergic REM-ON neurons in the PPT project to VTA, we proposed that such inputs might affect REMS, dreams and hallucinations. We recorded sleep-wake-REMS in freely moving, chronically prepared rats under three controlled experimental conditions. In different sets of experiments, either the ACh-ergic inputs to the VTA were blocked by local microinjection of Scopolamine (Scop) alone, or, the PPT neurons were bilaterally stimulated by Glutamate (Glut), or, the PPT neurons were stimulated by Glut in presence of Scop into the VTA. It was observed that Glut into PPT and Scop into the VTA significantly increased and decreased REMS, respectively. Additionally, PPT stimulation induced increased REMS was prevented in the presence of Scop into the VTA. Based on these findings we propose that inputs from ACh-ergic REM-ON neurons to VTA increase REMS and it could be a possible circuitry for expressions of hallucinations and dreams.

The alternations of nucleus accumbent in schizophrenia patients with auditory verbal hallucinations during low-frequency rTMS treatment

Low-frequency repetitive transcranial magnetic stimulation (rTMS) has been shown to reduce the severity of auditory verbal hallucinations (AVH) and induce beneficial functional and structural alternations of the brain in schizophrenia patients with AVH. The nucleus accumbens (NAcc) as an important component of the ventral striatum is implicated with the pathology in AVH. However, the induced characteristic patterns of NAcc by low-frequency rTMS in schizophrenia with AVH are seldom explored. We investigated the functional and structural characteristic patterns of NAcc by using seed-based functional connectivity (FC) analysis and gray matter volume (GMV) measurement in schizophrenia patients with AVH during 1 Hz rTMS treatment. Although low-frequency rTMS treatment did not affect the volumetric changes of NAcc, the abnormal FC patterns of NAcc, including increased FC of NAcc with the temporal lobes and decreased FC of NAcc with the frontal cortices in the pretreatment patients compared to healthy controls, were normalized or reversed after treatment. These FC changes were associated with improvements in clinical symptoms and neurocognitive functions. Our findings may extend our understanding of the NAcc in the pathology of schizophrenia with AVH and might be a biomarker of clinical effect for low-frequency rTMS treatment in schizophrenia.

The Etiology of Auditory Hallucinations in Schizophrenia: From Multidimensional Levels

Enormous efforts have been made to unveil the etiology of auditory hallucinations (AHs), and multiple genetic and neural factors have already been shown to have their own roles. Previous studies have shown that AHs in schizophrenia vary from those in other disorders, suggesting that they have unique features and possibly distinguishable mechanisms worthy of further investigation. In this review, we intend to offer a comprehensive summary of current findings related to AHs in schizophrenia from aspects of genetics and transcriptome, neurophysiology (neurometabolic and electroencephalogram studies), and neuroimaging (structural and functional magnetic resonance imaging studies and transcriptome–neuroimaging association study). Main findings include gene polymorphisms, glutamate level change, electroencephalographic alterations, and abnormalities of white matter fasciculi, cortical structure, and cerebral activities, especially in multiple regions, including auditory and language networks. More solid and comparable research is needed to replicate and integrate ongoing findings from multidimensional levels.

Functional Connectivity of Nucleus Accumbens Is Associated with Lifelong Premature Ejaculation in Male Adults : A Resting-state fMRI Study

PURPOSE

Ejaculation represents a crucial component of sexual behavior in men, which is involved in reward functions of certain brain areas including the nucleus accumbens (NAcc). Lifelong premature ejaculation (PE) is one of the most prevalent sexual dysfunctions in men. It is suggested to be related to abnormal brain function. This study aimed to explore changes of the functional connectivity patterns of NAcc and possible correlations of the neuroimaging abnormalities with clinical features in lifelong PE patients.

METHODS

The sample consisted with 42 lifelong PE patients and 30 healthy controls. All participants underwent functional magnetic resonance imaging scans and clinical symptoms. The functional connectivity (FC) approach was applied to investigate differences of NAcc-seed intrinsic connectivity between two groups and correlation analysis was used to access possible relationships between the imaging findings and clinical features, such as premature ejaculation diagnostic tool (PEDT) or intravaginal ejaculatory latency time (IELT).

RESULTS

Results showed that lifelong PE patients had decreased FC between the NAcc and thalamus, superior temporal pole, superior temporal cortex (STC), inferior frontal gyrus (IFG), orbitofrontal cortex, caudate and putamen. A significantly negative correlation between the PEDT score and NAcc-STC connectivity (r = -0.46) was found in lifelong PE patients, while IELT score positively correlated with the NAcc-IFG connectivity (r = 0.48) and NAcc-thalamus connectivity (r = 0.46).

CONCLUSION

The findings may facilitate a more sophisticated understanding of neural mechanisms of lifelong PE, particularly associated with the NAcc-related intrinsic connectivity during the resting state.

Knowledge domain and emerging trends in visual hallucination research: A scientometric analysis

BACKGROUND

Visual hallucination (VH) refers to a spontaneous visual perception without corresponding external stimuli and often occurs in ophthalmological and neuropsychiatric disorders. It is associated with poor quality of life, and increased patient hospitalization and nursing home admission. To date, a scientometric analysis of research on VH is lacking.

AIM

To objectively summarize the features of VH research and gain insights into the emerging trends in research on VH.

METHODS

CiteSpace V was used in this article. Publication outputs, document types, geographic distributions, co-authorship status, research hotspots, and co-citation status were analyzed. A total of 2176 original articles and 465 reviews were included in the database downloaded from the Web of Science Core Collection. We selected the top 50 most cited or occurring articles or items to create a visualized network with a 1-year interval. In the document co-citation analysis stage, we performed clustering analysis on co-cited references, and log likelihood tests were used to name the clusters.

RESULTS

The results showed that most publications can be classified into neurology, sports, and ophthalmology studies. In addition, North America, Europe, Asia and Australia published the most documents. Some well-known authors have always had a leading role in this field; meanwhile, new authors keep emerging. A relatively stable cooperation has been formed among many authors. Furthermore, neuropsychiatric symptom and functional connectivity are the top hotspots. Research on VH in dementia with Lewy bodies and Parkinson’s disease (PD) have received much attention. Studies on VH in PD are likely to be the new emerging trends in the future, especially the mechanisms of VH.

CONCLUSION

Research on VH has formed a complete system. More large-scale clinical and in-depth basic research are required to better understand the mechanisms underlying VH, which will contribute to our understanding of the pathophysiology and therapeutic options for VH.

Computational models of the "active self" and its disturbances in schizophrenia

The notion that self-disorders are at the root of the emergence of schizophrenia rather than a symptom of the disease, is getting more traction in the cognitive sciences. This is in line with philosophical approaches that consider an enactive self, constituted through action and interaction with the environment. We thereby analyze different definitions of the self and evaluate various computational theories lending to these ideas. Bayesian and predictive processing are promising approaches for computational modeling of the "active self". We evaluate their implementation and challenges in computational psychiatry and cognitive developmental robotics. We describe how and why embodied robotic systems provide a valuable tool in psychiatry to assess, validate, and simulate mechanisms of self-disorders. Specifically, mechanisms involving sensorimotor learning, prediction, and self-other distinction, can be assessed with artificial agents. This link can provide essential insights to the formation of the self and new avenues in the treatment of psychiatric disorders.

Lesions causing hallucinations localize to one common brain network

The brain regions responsible for hallucinations remain unclear. We studied 89 brain lesions causing hallucinations using a recently validated technique termed lesion network mapping. We found that hallucinations occurred following lesions to a variety of different brain regions, but these lesion locations fell within a single functionally connected brain network. This network was defined by connectivity to the cerebellar vermis, inferior cerebellum (bilateral lobule X), and the right superior temporal sulcus. Within this single hallucination network, additional connections with the lesion location dictated the sensory modality of the hallucination: lesions causing visual hallucinations were connected to the lateral geniculate nucleus in the thalamus while lesions causing auditory hallucinations were connected to the dentate nucleus in the cerebellum. Our results suggest that lesions causing hallucinations localize to a single common brain network, but additional connections within this network dictate the sensory modality, lending insight into the causal neuroanatomical substrate of hallucinations.

Dopaminergic Regulation of Reward System Connectivity Underpins Pain and Emotional Suffering in Migraine

Purpose

It has been suggested that reward system dysfunction may account for emotion and pain suffering in migraine. However, there is a lack of evidence whether the altered reward system connectivity is directly associated with clinical manifestations, including negative affect and ictal pain severity and, at the molecular level, the dopamine (DA) D2/D3 receptors (D2/3Rs) signaling implicated in encoding motivational and emotional cues.

Patients and Methods

We acquired resting-state functional MRI from interictal episodic migraine (EM) patients and age-matched healthy controls, as well as positron emission tomography (PET) with [¹¹C]raclopride, a selective radiotracer for DA D2/3Rs, from a subset of these participants. The nucleus accumbens (NAc) was seeded to measure functional connectivity (FC) and DA D2/3Rs availability based on its essential involvement in pain-related aversive/reward functions. Associations of the brain measures with positive/negative affect and ictal pain severity were also assessed.

Results

Compared with controls, the EM group showed weaker right NAc connectivity with areas implicated in pain and emotional regulation, such as the amygdala, rostral anterior cingulate cortex, hippocampus, and thalamus; but showed stronger left NAc connectivity with the dorsolateral prefrontal cortex and lingual gyrus. Moreover, among the altered NAc connectivities, only right NAc-amygdala connectivity was inversely correlated with DA D2/3Rs availability in migraine patients (diagnostic group-by-D2/3Rs interaction p < 0.007). At a clinical level, such weaker NAc-amygdala connectivity was associated with lower interictal positive affect and greater ictal pain severity over the head and facial extension area (pain area and intensity number summation, PAINS).

Conclusion

Together, our findings suggest that altered reward system connectivity, specifically between the NAc and amygdala, might be affected by endogenous DA D2/3Rs signaling, and such process might be a neural mechanism that underlies emotional and pain suffering in episodic migraineurs.

Interrelations between dopamine and serotonin producing sites and regions of the default mode network

Recent functional magnetic resonance imaging (fMRI) studies showed that blood oxygenation level-dependent (BOLD) signal fluctuations in the default mode network (DMN) are functionally tightly connected to those in monoaminergic nuclei, producing dopamine (DA), and serotonin (5-HT) transmitters, in the midbrain/brainstem. We combined accelerated fMRI acquisition with spectral Granger causality and coherence analysis to investigate causal relationships between these areas. Both methods independently lead to similar results and confirm the existence of a top-down information flow in the resting-state condition, where activity in core DMN areas influences activity in the neuromodulatory centers producing DA/5-HT. We found that latencies range from milliseconds to seconds with high inter-subject variability, likely attributable to the resting condition. Our novel findings provide new insights into the functional organization of the human brain.

The Phenomenology and Neurobiology of Visual Distortions and Hallucinations in Schizophrenia: An Update

Schizophrenia is characterized by visual distortions in ~60% of cases, and visual hallucinations (VH) in ~25-50% of cases, depending on the sample. These symptoms have received relatively little attention in the literature, perhaps due to the higher rate of auditory vs. visual hallucinations in psychotic disorders, which is the reverse of what is found in other neuropsychiatric conditions. Given the clinical significance of these perceptual disturbances, our aim is to help address this gap by updating and expanding upon prior reviews. Specifically, we: (1) present findings on the nature and frequency of VH and distortions in schizophrenia; (2) review proposed syndromes of VH in neuro-ophthalmology and neuropsychiatry, and discuss the extent to which these characterize VH in schizophrenia; (3) review potential cortical mechanisms of VH in schizophrenia; (4) review retinal changes that could contribute to VH in schizophrenia; (5) discuss relationships between findings from laboratory measures of visual processing and VH in schizophrenia; and (6) integrate findings across biological and psychological levels to propose an updated model of VH mechanisms, including how their content is determined, and how they may reflect vulnerabilities in the maintenance of a sense of self. In particular, we emphasize the potential role of alterations at multiple points in the visual pathway, including the retina, the roles of multiple neurotransmitters, and the role of a combination of disinhibited default mode network activity and enhanced state-related apical/contextual drive in determining the onset and content of VH. In short, our goal is to cast a fresh light on the under-studied symptoms of VH and visual distortions in schizophrenia for the purposes of informing future work on mechanisms and the development of targeted therapeutic interventions.

Altered Functional Connectivity of the Nucleus Accumbens Network Between Deficit and Non-deficit Schizophrenia

Deficit schizophrenia (DS), which is marked by stable negative symptoms, is regarded as a homogeneous subgroup of schizophrenia. While DS patients have structurally altered nucleus accumbens (NAcc) compared to non-deficit schizophrenia (NDS) patients and healthy individuals, the investigation of NAcc functional connectivity (FC) with negative symptoms and neurocognition could provide insights into the pathophysiology of schizophrenia. 58 DS, 93 NDS, and 113 healthy controls (HCs) underwent resting-state functional magnetic resonance (rsfMRI). The right and left NAcc were respectively used as seed points to construct the functional NAcc network in whole-brain FC analysis. ANCOVA compared the differences in NAcc network FC and partial correlation analysis explored the relationships between altered FC of NAcc, negative symptoms and neurocognition. Compared to HCs, both DS and NDS patients showed decreased FC between the left NAcc (LNAcc) and bilateral middle cingulate gyrus, and between the right NAcc (RNAcc) and right middle frontal gyrus (RMFG), as well as increased FC between bilateral NAcc and bilateral lingual gyrus. Moreover, the FC between the LNAcc and bilateral calcarine gyrus (CAL) was lower in the DS group compared to NDS patients. Correlation analysis indicated that FC value of LNAcc-CAL was negatively correlated to negative symptoms. Furthermore, aberrant FC values within the NAcc network were correlated with severity of clinical symptoms and neurocognitive impairments in DS and NDS patients. This study demonstrated abnormal patterns of FC in the NAcc network between DS and NDS. The presence of altered LNAcc-CAL FC might be involved in the pathogenesis of negative symptoms in schizophrenia.

Brain-on-a-Chip Device for Modeling Multiregional Networks

Animal models are frequently used in drug discovery because they represent a mammalian in vivo model system, they are the closest approximation to the human brain, and experimentation in humans is not ethical. Working with postmortem human brain samples is challenging and developing human in vitro systems, which mimic the in vivo human brain, has been challenging. However, the use of animal models in drug discovery for human neurological diseases is currently under scrutiny because data from animal models has come with variations due to genetic differences. Evidence from the literature suggests that techniques to reconstruct multiple neurotransmission projections, which characterize neurological disease circuits in humans, in vitro, have not been demonstrated. This paper presents a multicompartment microdevice for patterning neurospheres and specification of neural stem cell fate toward networks of multiple neuronal phenotypes. We validated our design by specification of human neural stem cells to dopaminergic and GABAergic neurons in different compartments of the device, simultaneously. The neurospheres formed unrestricted robust neuronal circuits between arrays of neurospheres in all compartments of the device. Such a device design may provide a basis for formation of multineurotransmission circuits to model functional connectivity between specific human brain regions, in vitro, using human-derived neural stem cells. This work finds relevance in neurological disease modeling and drug screening using human cell-based assays and may provide the impetus for shifting from animal-based models.

Differences in Functional Connectivity Networks Related to the Midbrain Dopaminergic System-Related Area in Various Psychiatric Disorders

OBJECTIVE

Disruptions in the dopamine system have been observed in psychiatric disorders. Since dopamine is mainly produced in the ventral tegmental area (VTA), elucidating the differences in the VTA neural network across psychiatric disorders would facilitate a greater understanding of the pathophysiological mechanisms underlying these disorders. However, no study has compared VTA-seed-based functional connectivity across psychiatric disorders. Therefore, we conducted a resting-state functional magnetic resonance imaging (rs-fMRI) study to perform a seed-based fMRI analysis, using the VTA as a seed.

METHODS

We included participants with major depressive disorder (MDD; n = 45), schizophrenia (n = 32), and bipolar disorder (BPD; n = 30), along with healthy control participants (n = 46) who were matched for age, gender, and handedness.

RESULTS

The results showed that patients with MDD and BPD had altered VTA-related connectivity in the superior frontal gyrus, frontal pole regions, hippocampus, cerebellum, and posterior cingulate cortex. Some of these differences in connectivity were also found between affective disorders and schizophrenia; however, there were no differences between the schizophrenia and control groups. Connectivity between the VTA and the hippocampus was correlated with positive symptoms in the schizophrenia group. The connectivity was not associated with medication dose, and the results remained significant after controlling for dose.

CONCLUSIONS

The results suggest that altered brain functional connectivity related to VTA networks could be associated with the distinctive pathophysiologies of psychiatric disorders, especially affective disorders.

Overlapping but Asymmetrical Relationships Between Schizophrenia and Autism Revealed by Brain Connectivity

Although the relationship between schizophrenia spectrum disorder (SSD) and autism spectrum disorder (ASD) has long been debated, it has not yet been fully elucidated. The authors quantified and visualized the relationship between ASD and SSD using dual classifiers that discriminate patients from healthy controls (HCs) based on resting-state functional connectivity magnetic resonance imaging. To develop a reliable SSD classifier, sophisticated machine-learning algorithms that automatically selected SSD-specific functional connections were applied to Japanese datasets from Kyoto University Hospital (N = 170) including patients with chronic-stage SSD. The generalizability of the SSD classifier was tested by 2 independent validation cohorts, and 1 cohort including first-episode schizophrenia. The specificity of the SSD classifier was tested by 2 Japanese cohorts of ASD and major depressive disorder. The weighted linear summation of the classifier's functional connections constituted the biological dimensions representing neural classification certainty for the disorders. Our previously developed ASD classifier was used as ASD dimension. Distributions of individuals with SSD, ASD, and HCs s were examined on the SSD and ASD biological dimensions. We found that the SSD and ASD populations exhibited overlapping but asymmetrical patterns in the 2 biological dimensions. That is, the SSD population showed increased classification certainty for the ASD dimension but not vice versa. Furthermore, the 2 dimensions were correlated within the ASD population but not the SSD population. In conclusion, using the 2 biological dimensions based on resting-state functional connectivity enabled us to discover the quantified relationships between SSD and ASD.

GBA Variants in Parkinson's Disease: Clinical, Metabolomic, and Multimodal Neuroimaging Phenotypes

BACKGROUND

Alterations in the GBA gene (NM_000157.3) are the most important genetic risk factor for Parkinson's disease (PD). Biallelic GBA mutations cause the lysosomal storage disorder Gaucher's disease. The GBA variants p.E365K and p.T408M are associated with PD but not with Gaucher's disease. The pathophysiological role of these variants needs to be further explored.

OBJECTIVE

This study analyzed clinical, neuropsychological, metabolic, and neuroimaging phenotypes of patients with PD carrying the GBA variants p.E365K and p.T408M.

METHODS

GBA was sequenced in 56 patients with mid-stage PD. Carriers of GBA variants were compared with noncarriers regarding clinical history and symptoms, neuropsychological features, metabolomics, and multimodal neuroimaging. Blood plasma gas chromatography coupled to mass spectrometry, 6-[¹⁸ F]fluoro-L-Dopa positron emission tomography (PET), [¹⁸ F]fluorodeoxyglucose PET, and resting-state functional magnetic resonance imaging were performed.

RESULTS

Sequence analysis detected 13 heterozygous GBA variant carriers (7 with p.E365K, 6 with p.T408M). One patient carried a GBA mutation (p.N409S) and was excluded. Clinical history and symptoms were not significantly different between groups. Global cognitive performance was lower in variant carriers. Metabolomic group differences were suggestive of more severe PD-related alterations in carriers versus noncarriers. Both PET scans showed signs of a more advanced disease; [¹⁸ F]fluorodeoxyglucose PET and functional magnetic resonance imaging showed similarities with Lewy body dementia and PD dementia in carriers.

CONCLUSIONS

This is the first study to comprehensively assess (neuro-)biological phenotypes of GBA variants in PD. Metabolomics and neuroimaging detected more significant group differences than clinical and behavioral evaluation. These alterations could be promising to monitor effects of disease-modifying treatments targeting glucocerebrosidase metabolism. © 2020 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

A Review of Multimodal Hallucinations: Categorization, Assessment, Theoretical Perspectives, and Clinical Recommendations

Hallucinations can occur in different sensory modalities, both simultaneously and serially in time. They have typically been studied in clinical populations as phenomena occurring in a single sensory modality. Hallucinatory experiences occurring in multiple sensory systems-multimodal hallucinations (MMHs)-are more prevalent than previously thought and may have greater adverse impact than unimodal ones, but they remain relatively underresearched. Here, we review and discuss: (1) the definition and categorization of both serial and simultaneous MMHs, (2) available assessment tools and how they can be improved, and (3) the explanatory power that current hallucination theories have for MMHs. Overall, we suggest that current models need to be updated or developed to account for MMHs and to inform research into the underlying processes of such hallucinatory phenomena. We make recommendations for future research and for clinical practice, including the need for service user involvement and for better assessment tools that can reliably measure MMHs and distinguish them from other related phenomena.

Antipsychotic agents deteriorate brain and retinal function in schizophrenia patients with combined auditory and visual hallucinations: A pilot study and secondary follow-up study

INTRODUCTION

Schizophrenia patients often experience auditory hallucinations (AHs) and visual hallucinations (VHs). However, the degree and type of brain and retinal alterations associated with combined AHs and VHs in schizophrenia patients remain unknown. There is an urgent need for a study that investigates the trajectory of brain and retinal alterations in patients with first-episode untreated schizophrenia accompanied by combined AHs and VHs (FUSCHAV).

METHODS

FUSCHAV patients (n = 120), divided into four groups according to AH and VH symptom severity (severe AHs combined with severe VHs [FUSCHSASV, 20 patients]; middle-to-moderate AHs combined with severe VHs [FUSCHMASV, 23 patients]; severe AHs combined with middle-to-moderate VHs [FUSCHSAMV, 28 patients]; and middle-to-moderate AHs combined with middle-to-moderate VHs [FUSCHMAMV, 26 patients]), were compared to healthy controls (n = 30). Gray matter volume (GMV) was adopted for brain structural alteration assessment. Total retinal thickness was adopted as a measure of retinal thickness impairment.

RESULTS

In the pilot study, the rate of GMV reduction showed an inverted U-shaped pattern across the different FUSCHAV patient groups according to AH and VH severity. The degree of retinal impairment remained stable across the groups. More notably, in the secondary follow-up study, we observed that, after 6 months of treatment with antipsychotic agents, all the GMV reduction-related differences across the different patient groups disappeared, and both GMV and retinal thickness demonstrated a tendency to deteriorate.

CONCLUSIONS

These findings indicate the need for heightened alertness on brain and retinal impairments in patients with FUSCHAV. Further deteriorations induced by antipsychotic agent treatment should be monitored in clinical practice.

Machine learning technique reveals intrinsic characteristics of schizophrenia: an alternative method

Machine learning technique has long been utilized to assist disease diagnosis, increasing clinical physicians' confidence in their decision and expediting the process of diagnosis. In this case, machine learning technique serves as a tool for distinguishing patients from healthy people. Additionally, it can also serve as an exploratory method to reveal intrinsic characteristics of a disease based on discriminative features, which was demonstrated in this study. Resting-state functional magnetic resonance imaging (fMRI) data were obtained from 148 participants (including patients with schizophrenia and healthy controls). Connective strengths were estimated by Pearson correlation for each pair of brain regions partitioned according to automated anatomical labelling atlas. Subsequently, consensus connections with high discriminative power were extracted under the circumstance of the best classification accuracy. Investigating these consensus connections, we found that schizophrenia group predominately exhibited weaker strengths of inter-regional connectivity compared to healthy group. Aberrant connectivities in both intra- and inter-hemispherical connections were observed. Within intra-hemispherical connections, the number of aberrant connections in the right hemisphere was more than that of the left hemisphere. In the exploration of large regions, we revealed that the serious dysconnectivities mainly appeared on temporal and occipital regions for the within-large-region connections; while connectivity disruption was observed on the connections from temporal region to occipital, insula and limbic regions for the between-large-region connections. The findings of this study corroborate previous conclusion of dysconnectivity in schizophrenia and further shed light on distribution patterns of dysconnectivity, which deepens the understanding of pathological mechanism of schizophrenia.

Map2k7 Haploinsufficiency Induces Brain Imaging Endophenotypes and Behavioral Phenotypes Relevant to Schizophrenia

c-Jun N-terminal kinase (JNK) signaling contributes to functional plasticity in the brain and cognition. Accumulating evidence implicates a role for MAP kinase kinase 7 (MAP2K7), a JNK activator encoded by the Map2k7 gene, and other JNK pathway components in schizophrenia (ScZ). Mice haploinsufficient for Map2k7 (Map2k7+/- mice) display ScZ-relevant cognitive deficits, although the mechanisms are unclear. Here we show that Map2k7+/- mice display translationally relevant alterations in brain function, including hippocampal and mesolimbic system hypermetabolism with a contrasting prefrontal cortex (PFC) hypometabolism, reminiscent of patients with ScZ. In addition Map2k7+/- mice show alterations in functional brain network connectivity paralleling those reported in early ScZ, including PFC and hippocampal hyperconnectivity and compromised mesolimbic system functional connectivity. We also show that although the cerebral metabolic response to ketamine is preserved, the response to dextroamphetamine (d-amphetamine) is significantly attenuated in Map2k7+/- mice, supporting monoamine neurotransmitter system dysfunction but not glutamate/NMDA receptor (NMDA-R) dysfunction as a consequence of Map2k7 haploinsufficiency. These effects are mirrored behaviorally with an attenuated impact of d-amphetamine on sensorimotor gating and locomotion, whereas similar deficits produced by ketamine are preserved, in Map2k7+/- mice. In addition, Map2k7+/- mice show a basal hyperactivity and sensorimotor gating deficit. Overall, these data suggest that Map2k7 modifies brain and monoamine neurotransmitter system function in a manner relevant to the positive and cognitive symptoms of ScZ.

Reality-monitoring deficits and visual hallucinations in schizophrenia

The presence of visual hallucinations in addition to auditory hallucinations (V + AH) is associated with poor prognosis in patients with schizophrenia. However, little consideration has been given to these symptoms and their underlying cognitive bases remain unclear. Based on cognitive models of hallucinations, we hypothesized that V + AH are underpinned by an impairment in reality-monitoring processes. The objective of the present study was to test whether reality-monitoring deficits were associated with V + AH in schizophrenia. This study examined reality-monitoring abilities in two groups of patients with schizophrenia: a group of patients with V + AH (n = 24) and a group of patients with AH only (n = 22). Patients with V + AH were significantly more likely to misremember imagined words as being perceived from an external source, compared to patients with AH only (p = 0.008, d = -0.82). In other words, V + AH patients display a larger externalization bias than patients with AH only. One explanation for these results could be that experiencing hallucinations in two sensory modalities may contribute to increased vividness of mental imagery and, in turn, lead to disruption in reality-monitoring processes. This study helps to refine our understanding of the cognitive processes underlying the presence of both auditory and visual hallucinations in patients with schizophrenia.

Chronic psychosocial stressors are associated with alterations in salience processing and corticostriatal connectivity

Psychosocial stressors including childhood adversity, migration, and living in an urban environment, have been associated with several psychiatric disorders, including psychotic disorders. The neural and psychological mechanisms mediating this relationship remain unclear. In parallel, alterations in corticostriatal connectivity and abnormalities in the processing of salience, are seen in psychotic disorders. Aberrant functioning of these mechanisms secondary to chronic stress exposure, could help explain how common environmental exposures are associated with a diverse range of symptoms. In the current study, we recruited two groups of adults, one with a high degree of exposure to chronic psychosocial stressors (the exposed group, n = 20), and one with minimal exposure (the unexposed group, n = 22). All participants underwent a resting state MRI scan, completed the Aberrant Salience Inventory, and performed a behavioural task - the Salience Attribution Test (SAT). The exposed group showed reduced explicit adaptive salience scores (cohen's d = 0.69, p = 0.03) and increased aberrant salience inventory scores (d = 0.65, p = 0.04). The exposed group also showed increased corticostriatal connectivity between the ventral striatum and brain regions previously implicated in salience processing. Corticostriatal connectivity in these regions negatively correlated with SAT explicit adaptive salience (r = -0.48, p = 0.001), and positively correlated with aberrant salience inventory scores (r = 0.42, p = 0.006). Furthermore, in a mediation analysis there was tentative evidence that differences in striato-cortical connectivity mediated the group differences in salience scores.

Functional Connectivity of the Striatum in Schizophrenia and Psychotic Bipolar Disorder

BACKGROUND

The striatum is abnormal in schizophrenia and possibly represents a common neurobiological mechanism underlying psychotic disorders. Resting-state functional magnetic resonance imaging studies have not reached a consensus regarding striatal dysconnectivity in schizophrenia, although these studies generally find impaired frontoparietal and salience network connectivity. The goal of the current study was to clarify the pattern of corticostriatal connectivity, including whether corticostriatal dysconnectivity is transdiagnostic and extends into psychotic bipolar disorder.

METHODS

We examined corticostriatal functional connectivity in 60 healthy subjects and 117 individuals with psychosis, including 77 with a schizophrenia spectrum illness and 40 with psychotic bipolar disorder. We conducted a cortical seed-based region-of-interest analysis with follow-up voxelwise analysis for any significant results. Further, a striatum seed-based analysis was conducted to examine group differences in connectivity between the striatum and the whole cortex.

RESULTS

Cortical region-of-interest analysis indicated that overall connectivity of the salience network with the striatum was reduced in psychotic disorders, which follow-up voxelwise analysis localized to the left putamen. Striatum seed-based analyses showed reduced ventral rostral putamen connectivity with the salience network portion of the medial prefrontal cortex in both schizophrenia and psychotic bipolar disorder.

CONCLUSIONS

The current study found evidence of transdiagnostic corticostriatal dysconnectivity in both schizophrenia and psychotic bipolar disorder, including reduced salience network connectivity, as well as reduced connectivity between the putamen and the medial prefrontal cortex. Overall, the current study points to the relative importance of salience network hypoconnectivity in psychotic disorders.

Visual hallucinations associated with multimodal hallucinations, suicide attempts and morbidity of illness in psychotic disorders

BACKGROUND

Visual hallucinations (VH) are a common, but understudied symptom of psychosis, experienced by individuals across diagnostic categories of psychotic and neuropsychiatric conditions. There are limited data on VH and associated clinical phenotypes in adult idiopathic psychotic disorders, which are needed to elucidate their relevance to psychotic illness paradigms.

METHOD

In this cross-sectional study, we examined clinical risk factors for VH in a well-characterized sample of 766 patients with adult psychotic disorders across diagnostic categories of schizophrenia (n = 227), schizoaffective disorder (n = 210), and bipolar I disorder (n = 329). The Structured Clinical Interview for DSM-IV-TR was used for diagnosis and symptom measurements.

RESULTS

The prevalence of VH was 26.1% (200/766). Multivariate logistic regression showed that VH were independently associated with the presence of hallucinations in other modalities, including auditory, tactile, olfactory, and gustatory hallucinations. History of a suicide attempt and catatonic behavior were also associated with VH. In addition, specific delusions were associated with VH, in particular, delusions of control, and religious, erotomanic and jealousy delusions. Diagnosis, negative symptoms, and family history of psychosis were not independent predictors of VH.

CONCLUSIONS

Results showed the clinical and disease relevance of VH as they were associated with severe morbidity of illness, including suicide attempts and catatonic behavior. Findings also suggest a phenotype associated with hallucinations in other modalities and specific types of delusions. Based on our findings, VH may be a significant factor in assessing for suicidality and illness severity, warranting clinical attention and further study of underlying mechanisms.

Neural Correlates of Auditory Verbal Hallucinations in Schizophrenia and the Therapeutic Response to Theta-Burst Transcranial Magnetic Stimulation

Auditory verbal hallucinations (AVHs) are a core symptom of schizophrenia, and resistant to antipsychotic medication in a substantial proportion of patients. This study aimed to investigate the neural correlates of AVHs in schizophrenia patients and its response to a modified continuous theta-burst stimulation (cTBS) by transcranial magnetic stimulation. In a cross-sectional experiment, resting-state functional magnetic resonance images were collected from 31 AVH schizophrenia patients, 26 non-AVH schizophrenia patients, and 33 sex-/age-matched healthy controls (HCs). Functional connectivity strength (FCS) maps were compared among groups by 1-way analysis of variance (ANOVA). In a longitudinal experiment, 16 and 11 AVH patients received real and sham cTBS treatment for 15 days, respectively. Notably, this was not a randomized control trail. Changes in AVH and FCS were analyzed by 2-way ANOVA and 2-sample t-test, respectively. In the cross-sectional experiment, comparison of FCS maps identified 8 clusters among groups, but only one cluster (in left cerebellum) differed significantly in AVH patients compared to both HCs and non-AVH patients. In the longitudinal experiment, the real cTBS group showed a greater improvement in symptoms and a larger FCS decrease in left cerebellum than the sham group. Pearson's correlation analysis indicated that baseline FCS of the overlapping cerebellum cluster (between the cross-sectional and longitudinal findings) was negatively correlated with symptom improvement in the real treatment group. These findings emphasize the role of the left cerebellum in both the pathophysiology and clinical treatment of AVHs in schizophrenia patients.

Frontostriatal network dysfunction as a domain-general mechanism underlying phantom perception

In the present study, we use resting state fMRI to investigate whether nucleus accumbens (NAc) and extended frontostriatal networks are involved in the pathology of auditory phantom perception, i.e., tinnitus, through a study of functional connectivity. We hypothesize that resting state functional connectivity involving NAc will be increased relative to what is observed in healthy subjects and that this connectivity will correlate with clinical measures of tinnitus such as percept loudness, duration of symptoms, etc. We show that a large sample of patients with chronic tinnitus (n = 90) features extensive functional connectivity involving NAc that is largely absent in healthy subjects (n = 94). We further show that connectivity involving NAc correlates significantly with tinnitus percept loudness and the duration of tinnitus symptoms, even after controlling for the effects of age and hearing loss. The loudness correlation, which involves NAc and parahippocampal cortex, is consistent with existing literature identifying the parahippocampus as a tinnitus generator. Our results further suggest that frontostriatal connectivity may predict the transition from acute to chronic tinnitus, analogous to what is seen in the pain literature. We discuss these ideas and suggest fruitful avenues for future research.

Using fMRI and machine learning to predict symptom improvement following cognitive behavioural therapy for psychosis

Cognitive behavioural therapy for psychosis (CBTp) involves helping patients to understand and reframe threatening appraisals of their psychotic experiences to reduce distress and increase functioning. Whilst CBTp is effective for many, it is not effective for all patients and the factors predicting a good outcome remain poorly understood. Machine learning is a powerful approach that allows new predictors to be identified in a data-driven way, which can inform understanding of the mechanisms underlying therapeutic interventions, and ultimately make predictions about symptom improvement at the individual patient level. Thirty-eight patients with a diagnosis of schizophrenia completed a social affect task during functional MRI. Multivariate pattern analysis assessed whether treatment response in those receiving CBTp (n = 22) could be predicted by pre-therapy neural responses to facial affect that was either threat-related (ambiguous ‘neutral’ faces perceived as threatening in psychosis, in addition to angry and fearful faces) or prosocial (happy faces). The models predicted improvement in psychotic (r = 0.63, p = 0.003) and affective (r = 0.31, p = 0.05) symptoms following CBTp, but not in the treatment-as-usual group (n = 16). Psychotic symptom improvement was predicted by neural responses to threat-related affect across sensorimotor and frontal-limbic regions, whereas affective symptom improvement was predicted by neural responses to fearful faces only as well as prosocial affect across sensorimotor and frontal regions. These findings suggest that CBTp most likely improves psychotic and affective symptoms in those endorsing more threatening appraisals and mood-congruent processing biases, respectively, which are explored and reframed as part of the therapy. This study improves our understanding of the neurobiology of treatment response and provides a foundation that will hopefully lead to greater precision and tailoring of the interventions offered to patients.

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Machine learning models using neuroimaging data can predict response to CBTp.

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Neural responses to social threat predicted improvement in psychotic symptoms.

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Activation related to different social stimuli predicted distinct symptom domains.

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Predictors included activity in the hippocampus, frontal, and sensorimotor regions.

Disrupted network cross talk, hippocampal dysfunction and hallucinations in schizophrenia

Hallucinations characterize schizophrenia, with approximately 59% of patients reporting auditory hallucinations and 27% reporting visual hallucinations. Prior neuroimaging studies suggest that hallucinations are linked to disrupted communication across distributed (sensory, salience-monitoring and subcortical) networks. Yet, our understanding of the neurophysiological mechanisms that underlie auditory and visual hallucinations in schizophrenia remains limited. This study integrates two resting-state functional magnetic resonance imaging (fMRI) analysis methods - amplitudes of low-frequency fluctuations (ALFF) and functional network connectivity (FNC) - to explore the hypotheses that (1) abnormal FNC between salience and sensory (visual/auditory) networks underlies hallucinations in schizophrenia, and (2) disrupted hippocampal oscillations (as measured by hippocampal ALFF) beget changes in FNC linked to hallucinations. Our first hypothesis was supported by the finding that schizophrenia patients reporting hallucinations have higher FNC between the salience network and an associative auditory network relative to healthy controls. Hippocampal ALFF was negatively associated with FNC between primary auditory cortex and the salience network in healthy subjects, but was positively associated with FNC between these networks in patients reporting hallucinations. These findings provide indirect support favoring our second hypothesis. We suggest future studies integrate fMRI with electroencephalogram (EEG) and/or magnetoencephalogram (MEG) methods to directly probe the temporal relation between altered hippocampal oscillations and changes in cross-network functional communication.

Multilevel convergence of interoceptive impairments in hypertension: New evidence of disrupted body-brain interactions

Interoception, the sensing of visceral body signals, involves an interplay between neural and autonomic mechanisms. Clinical studies into this domain have focused on patients with neurological and psychiatric disorders, showing that damage to relevant brain mechanisms can variously alter interoceptive functions. However, the association between peripheral cardiac-system alterations and neurocognitive markers of interoception remains poorly understood. To bridge this gap, we examined multidimensional neural markers of interoception in patients with early stage of hypertensive disease (HTD) and healthy controls. Strategically, we recruited only HTD patients without cognitive impairment (as shown by neuropsychological tests), brain atrophy (as assessed with voxel-based morphometry), or white matter abnormalities (as evidenced by diffusion tensor imaging analysis). Interoceptive domains were assessed through (a) a behavioral heartbeat detection task; (b) measures of the heart-evoked potential (HEP), an electrophysiological cortical signature of attention to cardiac signals; and (c) neuroimaging recordings (MRI and fMRI) to evaluate anatomical and functional connectivity properties of key interoceptive regions (namely, the insula and the anterior cingulate cortex). Relative to controls, patients exhibited poorer interoceptive performance and reduced HEP modulations, alongside an abnormal association between interoceptive performance and both the volume and functional connectivity of the above regions. Such results suggest that peripheral cardiac-system impairments can be associated with abnormal behavioral and neurocognitive signatures of interoception. More generally, our findings indicate that interoceptive processes entail bidirectional influences between the cardiovascular and the central nervous systems.

Subcortical Local Functional Hyperconnectivity in Cannabis Dependence

BACKGROUND

Cannabis abuse (CA) has been associated with psychopathology, including negative emotionality and higher risk of psychosis, particularly with early age of initiation. However, the mechanisms underlying this association are poorly understood. Because aberrant dopamine signaling is implicated in cannabis-associated psychopathology, we hypothesized that regular CA would be associated with altered resting-state functional connectivity in dopamine midbrain-striatal circuits.

METHODS

We examined resting-state brain activity of subcortical regions in 441 young adults from the Human Connectome Project, including 30 subjects with CA meeting DSM-IV criteria for dependence and 30 control subjects matched on age, sex, education, body mass index, anxiety, depression, and alcohol and tobacco usage.

RESULTS

Across all subjects, local functional connectivity density hubs in subcortical regions were most prominent in ventral striatum, hippocampus, amygdala, dorsal midbrain, and posterior-ventral brainstem. As hypothesized, subjects with CA showed markedly increased local functional connectivity density relative to control subjects, not only in ventral striatum (where nucleus accumbens is located) and midbrain (where substantia nigra and ventral tegmental nuclei are located) but also in brainstem and lateral thalamus. These effects were observed in the absence of significant differences in subcortical volumes and were most pronounced in individuals who began cannabis use earliest in life and who reported high levels of negative emotionality.

CONCLUSIONS

Together, these findings suggest that chronic CA is associated with changes in resting-state brain function, particularly in dopaminergic nuclei implicated in psychosis but that are also critical for habit formation and reward processing. These results shed light on neurobiological differences that may be relevant to psychopathology associated with cannabis use.

Network modeling of resting state connectivity points towards the bottom up theories of schizophrenia

The dysconnectivity theory of schizophrenia proposes that schizophrenia symptoms arise from abnormalities in neuronal synchrony. Resting-state Functional Connectivity (FC) techniques allow us to highlight synchronization of large-scale networks, the Resting-state Networks (RNs). A large body of work suggests that disruption of RN synchronization could give rise to specific schizophrenia symptoms. The present study aimed to explore within- and between-network FC strength of 34 RNs in 29 patients suffering from schizophrenia, and their relationships with schizophrenia symptoms. Resting-state data were analyzed using independent component analysis and dual-regression techniques. Our results showed that both within-RN and between-RN FC were disrupted in patients with schizophrenia, with a global trend toward weaker FC. This decrease affected more particularly visual, auditory and crossmodal binding networks. These alterations were correlated with negative symptoms, positive symptoms and hallucinations, indicating abnormalities in visual processing and crossmodal binding in schizophrenia. Moreover, we stressed an anomalous synchronization between a visual network and a network thought to be engaged in mental imaging processes, correlated with delusions and hallucinations. Altogether, our results supported the assumption that some schizophrenia symptoms may be related to low-order sensory alterations impacting higher-order cognitive processes, i.e. the "bottom-up" hypothesis of schizophrenia symptoms.

Disrupted Olfactory Integration in Schizophrenia: Functional Connectivity Study

BACKGROUND

Evidence for olfactory dysfunction in schizophrenia has been firmly established. However, in the typical understanding of schizophrenia, olfaction is not recognized to contribute to or interact with the illness. Despite the solid presence of olfactory dysfunction in schizophrenia, its relation to the rest of the illness remains largely unclear. Here, we aimed to examine functional connectivity of the olfactory bulb, olfactory tract, and piriform cortices and isolate the network that would account for the altered olfaction in schizophrenia.

METHODS

We examined the functional connectivity of these specific olfactory regions in order to isolate other brain regions associated with olfactory processing in schizophrenia. Using the resting state functional MRI data from the Center for Biomedical Research Excellence in Brain Function and Mental Illness, we compared 84 patients of schizophrenia and 90 individuals without schizophrenia.

RESULTS

The schizophrenia group showed disconnectivity between the anterior piriform cortex and the nucleus accumbens, between the posterior piriform cortex and the middle frontal gyrus, and between the olfactory tract and the visual cortices.

CONCLUSIONS

The current results suggest functional disconnectivity of olfactory regions in schizophrenia, which may account for olfactory dysfunction and disrupted integration with other sensory modalities in schizophrenia.

Unexpected global impact of VTA dopamine neuron activation as measured by opto-fMRI

Dopamine neurons in the ventral tegmental area (VTA) are strongly implicated in cognitive and affective processing as well as in psychiatric disorders, including schizophrenia, depression, attention-deficit hyperactivity disorder and substance abuse disorders. In human studies, dopamine-related functions are routinely assessed using functional magnetic resonance imaging (fMRI) measures of blood oxygenation-level-dependent (BOLD) signals during the performance of dopamine-dependent tasks. There is, however, a critical void in our knowledge about whether and how activation of VTA dopamine neurons specifically influences regional or global fMRI signals. Here, we used optogenetics in Th::Cre rats to selectively stimulate VTA dopamine neurons while simultaneously measuring global hemodynamic changes using BOLD and cerebral blood volume-weighted (CBVw) fMRI. Phasic activation of VTA dopamine neurons increased BOLD and CBVw fMRI signals in VTA-innervated limbic regions, including the ventral striatum (nucleus accumbens). Surprisingly, basal ganglia regions that receive sparse or no VTA dopaminergic innervation, including the dorsal striatum and the globus pallidus, were also activated. In fact, the most prominent fMRI signal increase in the forebrain was observed in the dorsal striatum that is not traditionally associated with VTA dopamine neurotransmission. These data establish causation between phasic activation of VTA dopamine neurons and global fMRI signals. They further suggest that mesolimbic and non-limbic basal ganglia dopamine circuits are functionally connected and thus provide a potential novel framework for understanding dopamine-dependent functions and interpreting data obtained from human fMRI studies.

Effort-Based Reinforcement Processing and Functional Connectivity Underlying Amotivation in Medicated Patients with Depression and Schizophrenia

Amotivation is a common phenotype of major depressive disorder and schizophrenia, which are clinically distinct disorders. Effective treatment targets and strategies can be discovered by examining the dopaminergic reward network function underlying amotivation between these disorders. We conducted an fMRI study in healthy human participants and medicated patients with depression and schizophrenia using an effort-based reinforcement task. We examined regional activations related to reward type (positive and negative reinforcement), effort level, and their composite value, as well as resting-state functional connectivities within the meso-striatal-prefrontal pathway. We found that integrated reward and effort values of low effort-positive reinforcement and high effort-negative reinforcement were behaviorally anticipated and represented in the putamen and medial orbitofrontal cortex activities. Patients with schizophrenia and depression did not show anticipation-related and work-related reaction time reductions, respectively. Greater amotivation severity correlated with smaller work-related putamen activity changes according to reward type in schizophrenia and effort level in depression. Patients with schizophrenia showed feedback-related putamen hyperactivity of low effort compared with healthy controls and depressed patients. The strength of medial orbitofrontal-striatal functional connectivity predicted work-related reaction time reduction of high effort negative reinforcement in healthy controls and amotivation severity in both patients with schizophrenia and those with depression. Patients with depression showed deficient medial orbitofrontal-striatal functional connectivity compared with healthy controls and patients with schizophrenia. These results indicate that amotivation in depression and schizophrenia involves different pathophysiology in the prefrontal-striatal circuitry.SIGNIFICANCE STATEMENT Amotivation is present in both depression and schizophrenia. However, treatment involves the use of drugs that enhance serotonin activity in depression and inhibit serotonin and dopamine activity in schizophrenia. Understanding how motivation processed in the mesocorticolimbic and nigostriatal pathways is affected in depression and schizophrenia is important in discovering treatment targets and strategies for amotivation. To our knowledge, this is the first study to compare patients with depression and schizophrenia in a common functional construct. By using an effort-based reinforcement task and examining resting-state functional connectivity in the dopaminergic network, we propose that difference in striato-orbitofrontal dysfunction in effort-based reinforcement between depression and schizophrenia may be related to differences in the extent of functional dysconnectivity in the dopaminergic pathway.

Striatal phosphodiesterase 10A and medial prefrontal cortical thickness in patients with schizophrenia: a PET and MRI study

The enzyme phosphodiesterase 10A (PDE10A) is abundant in striatal medium spiny neurons and has been implicated in the pathophysiology of schizophrenia in animal models and is investigated as a possible new pharmacological treatment target. A reduction of prefrontal cortical thickness is common in schizophrenia, but how this relates to PDE10A expression is unknown. Our study aim was to compare, we believe for the first time, the striatal non-displaceable binding potential (BP_ND) of the new validated PDE10A ligand [¹¹C]Lu AE92686 between patients with schizophrenia and healthy controls. Furthermore, we aimed to assess the correlation of PDE10A BP_ND to cortical thickness. Sixteen healthy male controls and 10 male patients with schizophrenia treated with clozapine, olanzapine or quetiapine were investigated with positron emission tomography (PET) and magnetic resonance imaging (MRI). Striatal binding potential (BP_ND) of [¹¹C]Lu AE92686 was acquired through dynamic PET scans and cortical thickness by structural MRI. Clinical assessments of symptoms and cognitive function were performed and the antipsychotic dosage was recorded. Patients with schizophrenia had a significantly lower BP_ND of [¹¹C]Lu AE92686 in striatum (P=0.003) than healthy controls. The striatal BP_ND significantly correlated to cortical thickness in the medial prefrontal cortex and superior frontal gyrus across patients with schizophrenia and healthy controls. No significant correlation was observed between the BP_ND for [¹¹C]Lu AE92686 in striatum and age, schizophrenia symptoms, antipsychotic dosage, coffee consumption, smoking, duration of illness or cognitive function in the patients. In conclusion, PDE10A may be important for functioning in the striato-cortical interaction and in the pathophysiology of schizophrenia.

A dimensional approach to modeling symptoms of neuropsychiatric disorders in the marmoset monkey

Some patients suffering from the same neuropsychiatric disorder may have no overlapping symptoms whilst others may share symptoms common to other distinct disorders. Therefore, the Research Domain Criteria initiative recognises the need for better characterisation of the individual symptoms on which to focus symptom-based treatment strategies. Many of the disorders involve dysfunction within the prefrontal cortex (PFC) and so the marmoset, due to their highly developed PFC and small size, is an ideal species for studying the neurobiological basis of the behavioural dimensions that underlie these symptoms.Here we focus on a battery of tests that address dysfunction spanning the cognitive (cognitive inflexibility and working memory), negative valence (fear generalisation and negative bias) and positive valence (anhedonia) systems pertinent for understanding disorders such as ADHD, Schizophrenia, Anxiety, Depression and OCD. Parsing the separable prefrontal and striatal circuits and identifying the selective neurochemical modulation (serotonin vs dopamine) that underlie cognitive dysfunction have revealed counterparts in the clinical domain. Aspects of the negative valence system have been explored both at individual- (trait anxiety and genetic variation in serotonin transporter) and circuit-based levels enabling the understanding of generalisation processes, negative biases and differential responsiveness to SSRIs. Within the positive valence system, the combination of cardiovascular and behavioural measures provides a framework for understanding motivational, anticipatory and consummatory aspects of anhedonia and their neurobiological mechanisms. Together, the direct comparison of experimental findings in marmosets with clinical studies is proving an excellent translational model to address the behavioural dimensions and neurobiology of neuropsychiatric symptoms. © 2016 Wiley Periodicals, Inc. Develop Neurobiol 77: 328-353, 2017.