A functional neuroanatomy of hallucinations in schizophrenia

An ontogenetic role for Broca's and related speech areas in schizophrenic auditory hallucinations? Evidence from sulcal pits analysis

The pathogenesis of auditory verbal hallucinations (AVH), a core symptom of schizophrenia, is unknown, but there is increasing interest in the possibility that it involves brain structural changes. We used a novel whole brain structural imaging technique, sulcal pits analysis, to measure different parameters of sulcal pits, the deepest points in each fold of the cerebral cortex, in 24 schizophrenia patients with continuous or near-continuous hallucinations (AVH-frequent) and 22 matched patients who had never experienced AVH (AVH-never). A matched group of 58 healthy controls (HC) were also examined. In comparison to the AVH-never patients, the AVH-frequent patients exhibited increased depth of sulcal pits in a region of the left inferior frontal cortex and anterior insula, overlapping with Broca's Area and Brodmann Area 47. A nearly identical result emerged in the comparison between AVH-frequent patients and the HC. These findings suggest that a neurodevelopmentally stable brain structural alteration may contribute to the manifestation of AVH in individuals later diagnosed with schizophrenia. This finding also has relevance for theoretical approaches to AVH, a leading example of which relates them to inner speech.

Resting-State Electroencephalographic Signatures Predict Treatment Efficacy of tACS for Refractory Auditory Hallucinations in Schizophrenic Patients

Transcranial alternating current stimulation (tACS) has been reported to treat refractory auditory hallucinations in schizophrenia. Despite diligent efforts, it is imperative to underscore that tACS does not uniformly demonstrate efficacy across all patients as with all treatments currently employed in clinical practice. The study aims to find biomarkers predicting individual responses to tACS, guiding treatment decisions, and preventing healthcare resource wastage. We divided 17 schizophrenic patients with refractory auditory hallucinations into responsive(RE) and non-responsive(NR) groups based on their auditory hallucination symptom reduction rates after one month of tACS treatment. The pre-treatment resting-state electroencephalogram(rsEEG) was recorded and then computed absolute power spectral density (PSD), Hjorth parameters (HPs, Hjorth activity (HA), Hjorth mobility (HM), and Hjorth complexity (HC) included) from different frequency bands to portray the brain oscillations. The results demonstrated that statistically significant differences localized within the high gamma frequency bands of the right brain hemisphere. Immediately, we input the significant dissociable features into popular machine learning algorithms, the Cascade Forward Neural Network achieved the best recognition accuracy of 93.87%. These findings preliminarily imply that high gamma oscillations in the right brain hemisphere may be the main influencing factor leading to different responses to tACS treatment, and incorporating rsEEG signatures could improve personalized decisions for integrating tACS in clinical treatment.

Altered functional connectivity and hyperactivity of the caudal hippocampus in schizophrenia compared with bipolar disorder: a resting state fMRI (functional magnetic resonance imaging) study

BACKGROUND

Schizophrenia patients frequently present with structural and functional abnormalities of the hippocampus (Hipp). Further, these abnormalities are often associated with specific symptom profiles.

AIM

To determine whether schizophrenia patients show specific functional connectivity (FC) and activity abnormalities in each hippocampal subregion compared to the BD (bipolar disorder) and HC (healthy control) groups.

METHODS

Basal activation state and functional connectivity (FC) in four subregions of the bilateral Hipp were examined: left caudal (cHipp_L), right caudal (cHipp_R), left rostral (rHipp_L), and right rostral (rHipp_R). Resting-state functional magnetic resonance images were obtained from 62 schizophrenia patients, 57 bipolar disorder (BD) patients, and 45 healthy controls (HCs), and analyzed for fractional amplitude of low-frequency fluctuations (fALFF) as a measure of basal neural activity and for whole-brain FC based on the hippocampal subregions.

RESULTS

The schizophrenia group exhibited greater fALFF in bilateral cHipp (the caudal part of hippocampus) and rHipp (the rostral part of hippocampus) subregions compared to BD and HC groups as well as increased FC between the bilateral cHipp and multiple brain regions, including the thalamus, putamen, middle frontal gyrus, parietal cortex, and precuneus. Moreover, fALFF values of the bilateral cHipp were positively correlated with the severity of clinical symptoms as measured by the Positive and Negative Syndrome Scale.

CONCLUSIONS

These findings confirm an important contribution of hippocampal dysfunction, especially of the cHipp, in schizophrenia. Further, hyper-connectivity and hyperactivity of the cHipp could serve as a biomarker for therapeutic development.

A working model of neural activity and phenomenal experience in psychosis

According to classical phenomenology, phenomenal experience is composed of perceptions (related to environmental stimuli) and imagery/ideas (unrelated to environmental stimuli). Intensity/vividness is supposed to represent the key phenomenal difference between perceptions and ideas, higher in perceptions than ideas, and thus the core subjective criterion to distinguish reality from imagination. At a neural level, phenomenal experience is related to brain activity in the sensory areas, driven by receptor stimulation (underlying perception) or associative areas (underlying imagery/ideas). An alteration of the phenomenal experience that leads to a loss of contact with reality characterizes psychosis, which mainly consists of hallucinations (false perceptions) and delusions (fixed ideas). According to the current data on their neural correlates across subclinical conditions and different neuropsychiatric disorders (such as schizophrenia), hallucinations are mainly associated with: transient (modality-specific) activations of sensory cortices (primarily superior temporal gyrus, occipito-temporal cortex, postcentral gyrus, and insula) during the hallucinatory experience; increased intrinsic activity/connectivity of associative/default-mode network (DMN) areas (primarily temporoparietal junction, posterior cingulate cortex, and medial prefrontal cortex); and deficits in the sensory systems. Analogously, delusions are mainly associated with increased intrinsic activity/connectivity of associative/DMN areas (primarily medial prefrontal cortex). Integrating these data into our three-dimensional model of neural activity and phenomenal-behavioral patterns, we propose the following model of psychosis. A functional/structural deficit in the sensory systems complemented by a functional reconfiguration of intrinsic brain activity favoring hyperactivity of associative/DMN areas may drive neuronal activations in the sensory (auditory/visual/somatosensory) areas and insular (interoceptive) areas with spatiotemporal configurations maximally independent from environmental stimuli and predominantly related to associative processing. This manifests in perception deficit and imagery/ideas composed of exteroceptive-like and interoceptive/affective-like elements that show a phenomenal intensity indistinguishable from perceptions, impairing the reality monitoring, along with minimal changeability by environmental stimuli, ultimately resulting in dissociation of the phenomenal experience from the environment, i.e., psychosis.

Orbitofrontal cortex hypergyrification in hallucinating schizophrenia patients: Surface ratio as a promising brain biomarker

The study of brain gyrification may provide useful information on the cytoarchitecture and connectivity of the brain. One of the methods that have been developed to estimate brain gyrification, known as surface ratio (SR), has not yet been studied in schizophrenia. Here we aimed to assess whether SR could provide new insights on the brain structure of schizophrenia patients and the severity of symptoms. We also computed a more established brain gyrification measure, namely absolute mean curvature (AMC). We analyzed 63 magnetic resonance images, 25 from schizophrenia patients with treatment-resistant auditory verbal hallucinations (SCH-H), 18 from schizophrenia patients without hallucinations (SCH-NH), and 20 from healthy controls (HC). The SR measure revealed that SCH-H patients had a more folded orbitofrontal cortex than SCH-NH patients and HC. Gyrification in this region was also negatively associated with positive symptoms, specifically with the delusions and conceptual disorganization items, only in the SCH-H group. Regarding the AMC measure, we identified two areas where HC showed more gyrification than SCH-H patients, but no relationships arose with symptoms. The hypergyrification of the orbitofrontal cortex displayed by SCH-H patients, as captured by the SR measure, suggests aberrant and/or excessive wiring in these patients, which in turn could give rise to auditory verbal hallucinations. Alternatively, we comment on potential compensatory mechanisms that may better explain the negative association between orbitofrontal gyrification and positive symptomatology. The SR measure captured the most relevant differences and associations, making it a promising biomarker in schizophrenia.

Altered intrinsic neural activity and its molecular analyses in first-episode schizophrenia with auditory verbal hallucinations

Background

Auditory verbal hallucinations (AVHs) are one of the signature positive symptoms of schizophrenia, affecting a substantial portion of patients with schizophrenia. These hallucinations seriously impact the lives of patients, resulting in a substantial social burden. Recent studies have shown a significant correlation between abnormal local brain activity and the neurobiological mechanisms of AVHs. However, it is not fully clear whether altered intrinsic brain activity in schizophrenia patients with AVHs is correlated with specific neurotransmitter systems.

Methods

We included 50 first-episode, drug-naïve schizophrenia patients with AVHs, 50 patients without AVHs (NAVHs), and 50 age- and sex-matched healthy controls (HCs). The amplitude of low-frequency fluctuation (ALFF) was utilized to explore the altered intrinsic brain activity in the AVH group. Subsequently, we spatially correlated the altered ALFF with neurotransmitter maps using JuSpace.

Results

In our study, compared to HCs, the AVH group exhibited significantly reduced ALFF in multiple brain regions, mainly including the left precuneus, bilateral supplementary motor areas, bilateral paracentral lobules, bilateral precentral gyri, and bilateral postcentral gyri. The NAVH group showed significantly reduced ALFF in the left inferior occipital gyrus, left calcarine gyrus, and left lingual gyrus compared to HCs. Furthermore, the AVH group showed higher ALFF in the right inferior frontal gyrus compared to the NAVH group. Additionally, these ALFF alterations in the AVH group were closely related to three neurotransmitters, including dopamine, serotonin and norepinephrine.

Conclusion

We link neurotransmitters to abnormal intrinsic brain activity in first-episode, drug-naïve schizophrenia patients with AVHs, contributing to a comprehensive understanding of the pathophysiological processes and treatment pathways underlying AVHs.

Correlation Between Cortical Thickness Abnormalities of the Olfactory Sulcus and Olfactory Identification Disorder and Persistent Auditory Verbal Hallucinations in Chinese Patients With Chronic Schizophrenia

BACKGROUND AND HYPOTHESIS

Persistent auditory verbal hallucinations (pAVHs) and olfactory identification impairment are common in schizophrenia (SCZ), but the neuroimaging mechanisms underlying both pAVHs and olfactory identification impairment are unclear. This study aimed to investigate whether pAVHs and olfactory identification impairment in SCZ patients are associated with changes in cortical thickness.

STUDY DESIGN

In this study, cortical thickness was investigated in 78 SCZ patients with pAVHs (pAVH group), 58 SCZ patients without AVHs (non-AVH group), and 83 healthy controls (HC group) using 3T magnetic resonance imaging. The severity of pAVHs was assessed by the Auditory Hallucination Rating Scale. Olfactory identification deficits were assessed using the Odor Stick Identification Test for Japanese (OSIT-J). In addition, the relationship between the severity of pAVHs and olfactory identification disorder and cortical thickness abnormalities was determined.

STUDY RESULTS

Significant reductions in cortical thickness were observed in the right medial orbital sulcus (olfactory sulcus) and right orbital sulcus (H-shaped sulcus) in the pAVH group compared to both the non-AVH and HC groups (P < .003, Bonferroni correction). Furthermore, the severity of pAVHs was found to be negatively correlated with the reduction in cortical thickness in the olfactory sulcus and H-shaped sulcus. Additionally, a decrease in cortical thickness in the olfactory sulcus showed a positive correlation with the OSIT-J scores (P < .05, false discovery rate correction).

CONCLUSIONS

Cortical thickness abnormalities in the olfactory sulcus may be a common neuroimaging mechanism for pAVHs and olfactory identification deficits in SCZ patients.

Contributions of Basal Ganglia Circuits to Perception, Attention, and Consciousness

Research into ascending sensory pathways and cortical networks has generated detailed models of perception. These same cortical regions are strongly connected to subcortical structures, such as the basal ganglia (BG), which have been conceptualized as playing key roles in reinforcement learning and action selection. However, because the BG amasses experiential evidence from higher and lower levels of cortical hierarchies, as well as higher-order thalamus, it is well positioned to dynamically influence perception. Here, we review anatomical, functional, and clinical evidence to demonstrate how the BG can influence perceptual processing and conscious states. This depends on the integrative relationship between cortex, BG, and thalamus, which allows contributions to sensory gating, predictive processing, selective attention, and representation of the temporal structure of events.

Episodic Visual Hallucinations, Inference and Free Energy

Understandings of how visual hallucinations appear have been highly influenced by generative approaches, in particular Friston's Active Inference conceptualization. Their core proposition is that these phenomena occur when hallucinatory expectations outweigh actual sensory data. This imbalance occurs as the brain seeks to minimize informational free energy, a measure of the distance between predicted and actual sensory data in a stationary open system. We review this approach in the light of old and new information on the role of environmental factors in episodic hallucinations. In particular, we highlight the possible relationship of specific visual triggers to the onset and offset of some episodes. We use an analogy from phase transitions in physics to explore factors which might account for intermittent shifts between veridical and hallucinatory vision. In these triggered forms of hallucinations, we suggest that there is a transient disturbance in the normal one-to-one correspondence between a real object and the counterpart perception such that this correspondence becomes between the real object and a hallucination. Generative models propose that a lack of information transfer from the environment to the brain is one of the key features of hallucinations. In contrast, we submit that specific information transfer is required at onset and offset in these cases. We propose that this transient one-to-one correspondence between environment and hallucination is mediated more by aberrant discriminative than by generative inference. Discriminative inference can be conceptualized as a process for maximizing shared information between the environment and perception within a self-organizing nonstationary system. We suggest that generative inference plays the greater role in established hallucinations and in the persistence of individual hallucinatory episodes. We further explore whether thermodynamic free energy may be an additional factor in why hallucinations are temporary. Future empirical research could productively concentrate on three areas. Firstly, subjective perceptual changes and parallel variations in brain function during specific transitions between veridical and hallucinatory vision to inform models of how episodes occur. Secondly, systematic investigation of the links between environment and hallucination episodes to probe the role of information transfer in triggering transitions between veridical and hallucinatory vision. Finally, changes in hallucinatory episodes over time to elucidate the role of learning on phenomenology. These empirical data will allow the potential roles of different forms of inference in the stages of hallucinatory episodes to be elucidated.

The antipsychotic agent sulpiride microinjected into the ventral pallidum restores positive symptom-like habituation disturbance in MAM-E17 schizophrenia model rats

Dysfunction of subcortical D2-like dopamine receptors (D2Rs) can lead to positive symptoms of schizophrenia, and their analog, the increased locomotor activity in schizophrenia model MAM-E17 rats. The ventral pallidum (VP) is a limbic structure containing D2Rs. The D2R antagonist sulpiride is a widespread antipsychotic drug, which can alleviate positive symptoms in human patients. However, it is still not known how sulpiride can influence positive symptoms via VP D2Rs. We hypothesize that the microinjection of sulpiride into the VP can normalize hyperactivity in MAM-E17 rats. In addition, recently, we showed that the microinjection of sulpirid into the VP induces place preference in neurotypical rats. Thus, we aimed to test whether intra-VP sulpiride can also have a rewarding effect in MAM-E17 rats. Therefore, open field-based conditioned place preference (CPP) test was applied in neurotypical (SAL-E17) and MAM-E17 schizophrenia model rats to test locomotor activity and the potential locomotor-reducing and rewarding effects of sulpiride. Sulpiride was microinjected bilaterally in three different doses into the VP, and the controls received only vehicle. The results of the present study demonstrated that the increased locomotor activity of the MAM-E17 rats was caused by habituation disturbance. Accordingly, larger doses of sulpiride in the VP reduce the positive symptom-analog habituation disturbance of the MAM-E17 animals. Furthermore, we showed that the largest dose of sulpiride administered into the VP induced CPP in the SAL-E17 animals but not in the MAM-E17 animals. These findings revealed that VP D2Rs play an important role in the formation of positive symptom-like habituation disturbances in MAM-E17 rats.

Cross-cohort replicable resting-state functional connectivity in predicting symptoms and cognition of schizophrenia

Schizophrenia (SZ) is a debilitating mental illness characterized by adolescence or early adulthood onset of psychosis, positive and negative symptoms, as well as cognitive impairments. Despite a plethora of studies leveraging functional connectivity (FC) from functional magnetic resonance imaging (fMRI) to predict symptoms and cognitive impairments of SZ, the findings have exhibited great heterogeneity. We aimed to identify congruous and replicable connectivity patterns capable of predicting positive and negative symptoms as well as cognitive impairments in SZ. Predictable functional connections (FCs) were identified by employing an individualized prediction model, whose replicability was further evaluated across three independent cohorts (BSNIP, SZ = 174; COBRE, SZ = 100; FBIRN, SZ = 161). Across cohorts, we observed that altered FCs in frontal-temporal-cingulate-thalamic network were replicable in prediction of positive symptoms, while sensorimotor network was predictive of negative symptoms. Temporal-parahippocampal network was consistently identified to be associated with reduced cognitive function. These replicable 23 FCs effectively distinguished SZ from healthy controls (HC) across three cohorts (82.7%, 90.2%, and 86.1%). Furthermore, models built using these replicable FCs showed comparable accuracies to those built using the whole-brain features in predicting symptoms/cognition of SZ across the three cohorts (r = .17-.33, p < .05). Overall, our findings provide new insights into the neural underpinnings of SZ symptoms/cognition and offer potential targets for further research and possible clinical interventions.

Eight-month intensive meditation-based intervention improves refractory hallucinations and delusions and quality of life in male inpatients with schizophrenia: a randomized controlled trial

AIM

This study investigated the impact of an 8-month daily-guided intensive meditation-based intervention (iMI) on persistent hallucinations/delusions and health-related quality of life (QoL) in male inpatients with schizophrenia with treatment-refractory hallucinations and delusions (TRHDs).

METHODS

A randomized controlled trial assigned 64 male inpatients with schizophrenia and TRHD equally to an 8-month iMI plus general rehabilitation program (GRP) or GRP alone. Assessments were conducted at baseline and the third and eighth months using the Positive and Negative Syndrome Scale (PANSS), 36-Item Short Form-36 (SF-36), and Five Facet Mindfulness Questionnaire (FFMQ). Primary outcomes measured PANSS reduction rates for total score, positive symptoms, and hallucinations/delusions items. Secondary outcomes assessed PANSS, SF-36, and FFMQ scores for psychotic symptoms, health-related QoL, and mindfulness skills, respectively.

RESULTS

In the primary outcome, iMI significantly improved the reduction rates of PANSS total score, positive symptoms, and hallucination/delusion items compared with GRP at both the third and eighth months. Treatment response rates (≥25% reduction) for these measures significantly increased in the iMI group at the eighth month. Concerning secondary outcomes, iMI significantly reduced PANSS total score and hallucination/delusion items, while increasing scores in physical activity and mindfulness skills at both the third and eighth months compared with GRP. These effects were more pronounced with an 8-month intervention compared with a 3-month intervention.

CONCLUSIONS

An iMI benefits patients with TRHDs by reducing persistent hallucinations/delusions and enhancing health-related QoL. Longer iMI duration yields superior treatment outcomes.

Altered brain responses to emotional auditory stimuli in AVH subjects: an fMRI study

Purpose: Auditory verbal hallucinations (AVH) are a frequently occurring phenomenon in which subjects hear verbal sounds in the absence of any external stimuli. The prevalence of auditory hallucinations in schizophrenia has been revealed in many studies. Healthy subjects may also experience auditory hallucinations without accompanying psychological or neurological disorders, and in rare cases they seek clinical assistance for this emotionally disturbing condition. The aim of this study was to investigate the neural basis of emotional disturbance in auditory hallucinating subjects who do not suffer from any psychological or neurological disorder. Materials and Methods: Fourteen subjects suffering from auditory hallucinations and 15 age- and sex-matched healthy controls were recruited in this study. All participants underwent fMRI in two experimental sessions. In the first experimental session, all participants from both groups listened to pleasant auditory stimuli. In the second session, both groups listened to unpleasant auditory stimuli. The auditory stimuli were obtained from the International Affective Digitized Sounds (IADS). Results: Compared with the healthy control group, AVH subjects exhibited significantly increased activation in limbic, auditory, and frontal regions. Conclusion: Current results suggest that AVH may induce functional reorganization in emotion-related brain regions.

Altered brain morphology and functional connectivity in postmenopausal women: automatic segmentation of whole-brain and thalamic subnuclei and resting-state fMRI

The transition to menopause is associated with various physiological changes, including alterations in brain structure and function. However, menopause-related structural and functional changes are poorly understood. The purpose of this study was not only to compare the brain volume changes between premenopausal and postmenopausal women, but also to evaluate the functional connectivity between the targeted brain regions associated with structural atrophy in postmenopausal women. Each 21 premenopausal and postmenopausal women underwent magnetic resonance imaging (MRI). T1-weighted MRI and resting-state functional MRI data were used to compare the brain volume and seed-based functional connectivity, respectively. In statistical analysis, multivariate analysis of variance, with age and whole brain volume as covariates, was used to evaluate surface areas and subcortical volumes between the two groups. Postmenopausal women showed significantly smaller cortical surface, especially in the left medial orbitofrontal cortex (mOFC), right superior temporal cortex, and right lateral orbitofrontal cortex, compared to premenopausal women (p < 0.05, Bonferroni-corrected) as well as significantly decreased functional connectivity between the left mOFC and the right thalamus was observed (p < 0.005, Monte-Carlo corrected). Although postmenopausal women did not show volume atrophy in the right thalamus, the volume of the right pulvinar anterior, which is one of the distinguished thalamic subnuclei, was significantly decreased (p < 0.05, Bonferroni-corrected). Taken together, our findings suggest that diminished brain volume and functional connectivity may be linked to menopause-related symptoms caused by the lower sex hormone levels.

Functional magnetic resonance imaging in schizophrenia: current evidence, methodological advances, limitations and future directions

Functional neuroimaging emerged with great promise and has provided fundamental insights into the neurobiology of schizophrenia. However, it has faced challenges and criticisms, most notably a lack of clinical translation. This paper provides a comprehensive review and critical summary of the literature on functional neuroimaging, in particular functional magnetic resonance imaging (fMRI), in schizophrenia. We begin by reviewing research on fMRI biomarkers in schizophrenia and the clinical high risk phase through a historical lens, moving from case-control regional brain activation to global connectivity and advanced analytical approaches, and more recent machine learning algorithms to identify predictive neuroimaging features. Findings from fMRI studies of negative symptoms as well as of neurocognitive and social cognitive deficits are then reviewed. Functional neural markers of these symptoms and deficits may represent promising treatment targets in schizophrenia. Next, we summarize fMRI research related to antipsychotic medication, psychotherapy and psychosocial interventions, and neurostimulation, including treatment response and resistance, therapeutic mechanisms, and treatment targeting. We also review the utility of fMRI and data-driven approaches to dissect the heterogeneity of schizophrenia, moving beyond case-control comparisons, as well as methodological considerations and advances, including consortia and precision fMRI. Lastly, limitations and future directions of research in the field are discussed. Our comprehensive review suggests that, in order for fMRI to be clinically useful in the care of patients with schizophrenia, research should address potentially actionable clinical decisions that are routine in schizophrenia treatment, such as which antipsychotic should be prescribed or whether a given patient is likely to have persistent functional impairment. The potential clinical utility of fMRI is influenced by and must be weighed against cost and accessibility factors. Future evaluations of the utility of fMRI in prognostic and treatment response studies may consider including a health economics analysis.

Efficacy of transcranial alternating current stimulation for schizophrenia treatment: A systematic review

BACKGROUND

Transcranial alternating current stimulation (tACS) is an innovative noninvasive technique in brain stimulation that involves applying a low-intensity electrical current to the scalp. And increasing evidence has revealed its potential in schizophrenia treatment.

OBJECTIVE

This systematic review aimed to evaluate the efficacy of tACS as a novel neurostimulation technique for improving cognitive impairment and alleviating psychotic symptoms in schizophrenia. Additionally, this review attempted to explore the impact of stimulation parameters on the effectiveness of tACS treatment.

METHODS

A systematic literature search was conducted across five databases, including Web of Science, Embase, PubMed, CENTRAL, and PsycINFO, to identify studies investigating the use of tACS in schizophrenia. Only studies that involved the experimental use of tACS in patients with schizophrenia were included in this review.

RESULTS

Nineteen studies were included in this review. The most frequently used current intensities were 2 mA and 1 mA, and the most commonly used frequencies were alpha (10 Hz), theta (4.5 Hz and 6 Hz), and gamma (40 Hz). Some studies showed that tACS may have a potential therapeutic effect by improving cognitive functions in various cognitive domains and/or ameliorating negative symptoms, hallucinations, and delusions in patients with schizophrenia, while others showed no significant change. These studies also implicated that tACS treatment is safe and well tolerated.

CONCLUSIONS

Overall, this systematic review suggests that tACS has promise as a novel, effective, and adjunctive treatment approach for treating schizophrenia. Future research is needed to determine the optimal parameters of tACS for treating this complex disorder.

Dysregulated noradrenergic response is associated with symptom severity in individuals with schizophrenia

Introduction

The locus coeruleus-noradrenaline (LC-NA) system is involved in a wide range of cognitive functions and may be altered in schizophrenia. A non-invasive method to indirectly measure LC activity is task-evoked pupillary response. Individuals with schizophrenia present reduced pupil dilation compared to healthy subjects, particularly when task demand increases. However, the extent to which alteration in LC activity contributes to schizophrenia symptomatology remains largely unexplored. We aimed to investigate the association between symptomatology, cognition, and noradrenergic response in individuals with schizophrenia.

Methods

We assessed task-evoked pupil dilation during a pro- and antisaccade task in 23 individuals with schizophrenia and 28 healthy subjects.

Results

Both groups showed similar preparatory pupil dilation during prosaccade trials, but individuals with schizophrenia showed significantly lower pupil dilation compared to healthy subjects in antisaccade trials. Importantly, reduced preparatory pupil dilation for antisaccade trials was associated with worse general symptomatology in individuals with schizophrenia.

Discussion

Our findings suggest that changes in LC-NA activity - measured by task-evoked pupil dilation - when task demand increases is associated with schizophrenia symptoms. Interventions targeting the modulation of noradrenergic responses may be suitable candidates to reduce schizophrenia symptomatology.

Brain-region-specific changes in neurons and glia and dysregulation of dopamine signaling in Grin2a mutant mice

A genetically valid animal model could transform our understanding of schizophrenia (SCZ) disease mechanisms. Rare heterozygous loss-of-function (LoF) mutations in GRIN2A, encoding a subunit of the NMDA receptor, greatly increase the risk of SCZ. By transcriptomic, proteomic, and behavioral analyses, we report that heterozygous Grin2a mutant mice show (1) large-scale gene expression changes across multiple brain regions and in neuronal (excitatory and inhibitory) and non-neuronal cells (astrocytes and oligodendrocytes), (2) evidence of hypoactivity in the prefrontal cortex (PFC) and hyperactivity in the hippocampus and striatum, (3) an elevated dopamine signaling in the striatum and hypersensitivity to amphetamine-induced hyperlocomotion (AIH), (4) altered cholesterol biosynthesis in astrocytes, (5) a reduction in glutamatergic receptor signaling proteins in the synapse, and (6) an aberrant locomotor pattern opposite of that induced by antipsychotic drugs. These findings reveal potential pathophysiologic mechanisms, provide support for both the "hypo-glutamate" and "hyper-dopamine" hypotheses of SCZ, and underscore the utility of Grin2a-deficient mice as a genetic model of SCZ.

Associations of resting-state perfusion and auditory verbal hallucinations with and without emotional content in schizophrenia

Auditory Verbal Hallucinations (AVH) are highly prevalent in patients with schizophrenia. AVH with high emotional content lead to particularly poor functional outcome. Increasing evidence shows that AVH are associated with alterations in structure and function in language and memory related brain regions. However, neural correlates of AVH with emotional content remain unclear. In our study (n = 91), we related resting-state cerebral perfusion to AVH and emotional content, comparing four groups: patients with AVH with emotional content (n = 13), without emotional content (n = 14), without hallucinations (n = 20) and healthy controls (n = 44). Patients with AVH and emotional content presented with increased perfusion within the amygdala and the ventromedial and dorsomedial prefrontal cortex (vmPFC/ dmPFC) compared to patients with AVH without emotional content. In addition, patients with any AVH showed hyperperfusion within the anterior cingulate gyrus, the vmPFC/dmPFC, the right hippocampus, and the left pre- and postcentral gyrus compared to patients without AVH. Our results indicate metabolic alterations in brain areas critical for the processing of emotions as key for the pathophysiology of AVH with emotional content. Particularly, hyperperfusion of the amygdala may reflect and even trigger emotional content of AVH, while hyperperfusion of the vmPFC/dmPFC cluster may indicate insufficient top-down amygdala regulation in patients with schizophrenia.

Excessive fear of clusters of holes, its interaction with stressful life events and the association with anxiety and depressive symptoms: large epidemiological study of young people in Hong Kong

BACKGROUND

Excessive and persistent fear of clusters of holes, also known as trypophobia, has been suggested to reflect cortical hyperexcitability and may be associated with mental health risks. No study, however, has yet examined these associations in representative epidemiological samples.

AIMS

To examine the prevalence of trypophobia in a population-representative youth sample, its association with mental health and functioning, and its interaction with external stress.

METHOD

A total of 2065 young people were consecutively recruited from a household-based epidemiological youth mental health study in Hong Kong. Trypophobia, symptoms of anxiety, depression and stress, and exposure to personal stressors were assessed. Logistic regression was used to assess the relationships between trypophobia and mental health. Potential additive and interaction effects of trypophobia and high stress exposure on mental health were also tested.

RESULTS

The prevalence of trypophobia was 17.6%. Trypophobia was significantly associated with severe symptoms of anxiety (odds ratio (OR) = 1.83, 95% CI = 1.32-2.53), depression (OR = 1.78, 95% CI = 1.24-2.56) and stress (OR = 1.68, 95% CI = 1.11-2.53), even when accounting for sociodemographic factors, personal and family psychiatric history, resilience and stress exposure. Dose-response relationships were observed, and trypophobia significantly potentiated the effects of stress exposure on symptom outcomes, particularly for depressive symptoms. Those with trypophobia also showed significantly poorer functioning across domains and poorer health-related quality of life.

CONCLUSIONS

Screening for trypophobia in young people may facilitate early risk detection and intervention, particularly among those with recent stress exposure. Nevertheless, the generally small effect sizes suggest that other factors have more prominent roles in determining recent mental health outcomes in population-based samples; these should be explored in future work.

Excitatory and inhibitory imbalances in the trisynaptic pathway in the hippocampus in schizophrenia: a postmortem ultrastructural study

BACKGROUND

A preponderance of evidence suggests that the hippocampus is a key region of dysfunction in schizophrenia. Neuroimaging and other studies indicate a relationship between hippocampal dysfunction and the degree of psychosis. Clinical data indicate hyperactivity in the hippocampus that precedes the onset of psychosis, and is correlated with symptom severity. In this study, we sought to identify circuitry at the electron microscopic level that could contribute to region-specific imbalances in excitation and inhibition in the hippocampus in schizophrenia. We used postmortem tissue from the anterior hippocampus from patients with schizophrenia and matched controls. Using stereological techniques, we counted and measured synapses, postsynaptic densities (PSDs), and evaluated size, number and optical density of mitochondria and parvalbumin-containing interneurons in key nodes of the trisynaptic pathway. Compared to controls, the schizophrenia group had decreased numbers of inhibitory synapses in CA3 and increased numbers of excitatory synapses in CA1; together, this indicates deficits in inhibition and an increase in excitation. The thickness of the PSD was larger in excitatory synapses in CA1, suggesting greater synaptic strength. In the schizophrenia group, there were fewer mitochondria in the dentate gyrus and a decrease in the optical density, a measure of functional integrity, in CA1. The number and optical density of parvalbumin interneurons were lower in CA3. The results suggest region-specific increases in excitatory circuitry, decreases in inhibitory neurotransmission and fewer or damaged mitochondria. These results are consistent with the hyperactivity observed in the hippocampus in schizophrenia in previous studies.

Circadian rhythms in auditory hallucinations and psychosis

Circadian rhythms are imprinted in all organisms and influence virtually all aspects of physiology and behavior in adaptation to the 24-h day-night cycle. This recognition of a circadian timekeeping system permeating essentially all healthy functioning of body and mind quickly leads to the realization that, in turn, human ailments should be probed for the degree to which they are rooted in or marked by disruptions and dysregulations of circadian clock functions in the human body. In this review, we will focus on psychosis as a key mental illness and foremost one of its cardinal symptoms: auditory hallucinations. We will discuss recent empirical evidence and conceptual advances probing the potential role of circadian disruption in auditory hallucinations. Moreover, a dysbalance in excitation and inhibition within cortical networks, which in turn drive a disinhibition of dopaminergic signaling, will be highlighted as central physiological mechanism. Finally, we will propose two avenues for experimentally intervening on the circadian influences to potentially alleviate hallucinations in psychotic disorders.

An evolutionary account of impairment of self in cognitive disorders

Recent research has proposed that certain aspects of psychosis, as experienced in, e.g., schizophrenia (SCZ), but also aspects of other cognitive conditions, such as autism spectrum disorders (ASD) and synesthesia, can be related to a shattered sense of the notion of self. In this paper, our goal is to show that altered processing of self can be attributed to an abnormal functioning of cortico-striatal brain networks supporting, among other, one key human distinctive cognitive ability, namely cross-modality, which plays multiple roles in human cognition and language. Specifically, our hypothesis is that this cognitive mechanism sheds light both on some basic aspects of the minimal self and on some aspects related to higher forms of self, such as the narrative self. We further link the atypical functioning in these conditions to some recent evolutionary changes in our species, specifically, an atypical presentation of human self-domestication (HSD) features. In doing so, we also lean on previous work concerning the link between cognitive disorders and language evolution under the effects of HSD. We further show that this approach can unify both linguistic and non-linguistic symptoms of these conditions through deficits in the notion of self. Our considerations provide further support for the hypothesis that SCZ and ASD are diametrically opposed cognitive conditions, as well for the hypothesis that their etiology is associated with recent human evolution, leading to a deeper understanding of the causes and symptoms of these disorders, and providing new cues, which can be used for an earlier and more accurate diagnostics.

The Poly I:C maternal immune stimulation model shows unique patterns of brain metabolism, morphometry, and plasticity in female rats

Introduction: Prenatal infections are associated with an increased risk of the onset of schizophrenia. Rodent models of maternal immune stimulation (MIS) have been extensively used in preclinical studies. However, many of these studies only include males, omitting pathophysiological features unique to females. The aim of this study is to characterize the MIS model in female rats using positron emission tomography (PET), structural magnetic resonance imaging (MR), and neuroplasticiy studies. Methods: In gestational day 15, Poly I:C (or Saline) was injected into pregnant Wistar rats to induce the MIS model. Imaging studies: [¹⁸F]-fluoro-2-deoxy-D-glucose-PET scans of female-offspring were acquired at post-natal day (PND) 35 and PND100. Furthermore, T2-MR brain images were acquired in adulthood. Differences in FDG uptake and morphometry between groups were assessed with SPM12 and Regions of Interest (ROI) analyses. Ex vivo study: The density of parvalbumin expressing interneurons (PV), perineuronal nets (PNN), and parvalbumin expressing interneurons surrounded by perineuronal nets (PV-PNN) were evaluated in the prelimbic cortex and basolateral amygdala using confocal microscopy. ROIs and neuroplasticity data were analyzed by 2-sample T-test and 2-way-ANOVA analyses, respectively. Results: A significant increase in brain metabolism was found in all animals at adulthood compared to adolescence. MIS hardly modified brain glucose metabolism in females, highlighting a significant hypometabolism in the thalamus at adulthood. In addition, MIS induced gray matter (GM) enlargements in the pituitary, hippocampus, substantia nigra, and cingulate cortex, and GM shrinkages in some thalamic nuclei, cerebelar areas, and brainstem. Moreover, MIS induced white matter shrinkages in the cerebellum, brainstem and corpus callosum, along with cerebrospinal fluid enlargements in the lateral and 4th ventricles. Finally, MIS reduced the density of PV, PNN, and PV-PNN in the basolateral amygdala. Conclusion: Our work showed in vivo the differential pattern of functional and morphometric affectation in the MIS model in females, as well as the deficits caused at the synaptic level according to sex. The differences obtained highlight the relevance of including both sexes in psychiatric research in order to consider their pathophysiological particularities and successfully extend the benefits obtained to the entire patient population.

Targeting the pathological network: Feasibility of network-based optimization of transcranial magnetic stimulation coil placement for treatment of psychiatric disorders

It has been recognized that the efficacy of TMS-based modulation may depend on the network profile of the stimulated regions throughout the brain. However, what profile of this stimulation network optimally benefits treatment outcomes is yet to be addressed. The answer to the question is crucial for informing network-based optimization of stimulation parameters, such as coil placement, in TMS treatments. In this study, we aimed to investigate the feasibility of taking a disease-specific network as the target of stimulation network for guiding individualized coil placement in TMS treatments. We present here a novel network-based model for TMS targeting of the pathological network. First, combining E-field modeling and resting-state functional connectivity, stimulation networks were modeled from locations and orientations of the TMS coil. Second, the spatial anti-correlation between the stimulation network and the pathological network of a given disease was hypothesized to predict the treatment outcome. The proposed model was validated to predict treatment efficacy from the position and orientation of TMS coils in two depression cohorts and one schizophrenia cohort with auditory verbal hallucinations. We further demonstrate the utility of the proposed model in guiding individualized TMS treatment for psychiatric disorders. In this proof-of-concept study, we demonstrated the feasibility of the novel network-based targeting strategy that uses the whole-brain, system-level abnormity of a specific psychiatric disease as a target. Results based on empirical data suggest that the strategy may potentially be utilized to identify individualized coil parameters for maximal therapeutic effects.

Alpha transcranial alternating current stimulation reduces depressive symptoms in people with schizophrenia and auditory hallucinations: a double-blind, randomized pilot clinical trial

People with schizophrenia exhibit reduced alpha oscillations and frontotemporal coordination of brain activity. Alpha oscillations are associated with top-down inhibition. Reduced alpha oscillations may fail to censor spurious endogenous activity, leading to auditory hallucinations. Transcranial alternating current stimulation (tACS) at the alpha frequency was shown to enhance alpha oscillations in people with schizophrenia and may thus be a network-based treatment for auditory hallucinations. We conducted a double-blind, randomized, placebo-controlled pilot clinical trial to examine the efficacy of 10-Hz tACS in treating auditory hallucinations in people with schizophrenia. 10-Hz tACS was administered in phase at the dorsolateral prefrontal cortex and the temporoparietal junction with a return current at Cz. Patients were randomized to receive tACS or sham for five consecutive days during the treatment week (40 min/day), followed by a maintenance period, during which participants received weekly tACS (40 min/visit) or sham. tACS treatment reduced general psychopathology (p < 0.05, Cohen's d = -0.690), especially depression (p < 0.005, Cohen's d = -0.806), but not auditory hallucinations. tACS treatment increased alpha power in the target region (p < 0.05), increased the frequency of peak global functional connectivity towards 10 Hz (p < 0.05), and reduced left-right frontal functional connectivity (p < 0.005). Importantly, changes in brain functional connectivity significantly correlated with symptom improvement (p < 0.05). Daily 10 Hz-tACS increased alpha power and altered alpha-band functional connectivity. Successful target engagement reduced depression and other general psychopathology symptoms, but not auditory hallucinations. Considering existing research of 10Hz tACS as a treatment for major depressive disorder, our study demonstrates its transdiagnostic potential for treating depression.

Brain correlates of speech perception in schizophrenia patients with and without auditory hallucinations

The experience of auditory verbal hallucinations (AVH, "hearing voices") in schizophrenia has been found to be associated with reduced auditory cortex activation during perception of real auditory stimuli like tones and speech. We re-examined this finding using 46 patients with schizophrenia (23 with frequent AVH and 23 hallucination-free), who underwent fMRI scanning while they heard words, sentences and reversed speech. Twenty-five matched healthy controls were also examined. Perception of words, sentences and reversed speech all elicited activation of the bilateral superior temporal cortex, the inferior and lateral prefrontal cortex, the inferior parietal cortex and the supplementary motor area in the patients and the healthy controls. During the sentence and reversed speech conditions, the schizophrenia patients as a group showed reduced activation in the left primary auditory cortex (Heschl's gyrus) relative to the healthy controls. No differences were found between the patients with and without hallucinations in any condition. This study therefore fails to support previous findings that experience of AVH attenuates speech-perception-related brain activations in the auditory cortex. At the same time, it suggests that schizophrenia patients, regardless of presence of AVH, show reduced activation in the primary auditory cortex during speech perception, a finding which could reflect an early information processing deficit in the disorder.

A graph theory neuroimaging approach to distinguish the depression of bipolar disorder from major depressive disorder in adolescents and young adults

BACKGROUND

Markers to differentiate depressions of bipolar disorder (BD-Dep) from depressions of major depressive disorder (MDD-Dep), and for more targeted treatments, are critically needed to decrease current high rates of misdiagnosis that can lead to ineffective or potentially deleterious treatments. Distinguishing, and specifically treating the depressions, during the adolescent/young adult epoch is especially important to decrease illness progression and improve prognosis, and suicide, as it is the epoch when suicide thoughts and behaviors often emerge. With differences in functional connectivity patterns reported when BD-Dep and MDD-Dep have been studied separately, this study used a graph theory approach aimed to identify functional connectivity differences in their direct comparison.

METHODS

Functional magnetic resonance imaging whole-brain functional connectivity (Intrinsic Connectivity Distribution, ICD) measures were compared across adolescents/young adults with BD-Dep (n = 28), MDD-Dep (n = 20) and HC (n = 111). Follow-up seed-based connectivity was conducted on regions of significant ICD differences. Relationships with demographic and clinical measures were assessed.

RESULTS

Compared to the HC group, both the BD-Dep and MDD-Dep groups exhibited left-sided frontal, insular, and medial temporal ICD increases. The BD-Dep group had additional right-sided ICD increases in frontal, basal ganglia, and fusiform areas. In seed-based analyses, the BD-Dep group exhibited increased interhemispheric functional connectivity between frontal areas not seen in the MDD-Dep group.

LIMITATIONS

Modest sample size; medications not studied systematically.

CONCLUSIONS

This study supports bilateral and interhemispheric functional dysconnectivity as features of BD-Dep that may differentiate it from MDD-Dep in adolescents/young adults and serve as a target for early diagnosis and treatment strategies.

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

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

Immune Activation in Pregnant Rats Affects Brain Glucose Consumption, Anxiety-like Behaviour and Recognition Memory in their Male Offspring

PURPOSE

Prenatal infection during pregnancy is a risk factor for schizophrenia, as well as for other developmental psychiatric disorders, such as autism and bipolar disorder. Schizophrenia patients were reported to have altered brain metabolism and neuroinflammation. However, the link between prenatal infection, altered brain inflammation and metabolism, and schizophrenia remains unclear. In this project, we aimed to evaluate whether there are changes in brain glucose consumption and microglia activation in the offspring of pregnant rats exposed to maternal immune activation (MIA), and if so, whether these changes occur before or after the initiation of schizophrenia-like behaviour.

PROCEDURES

Pregnant rats were treated with the viral mimic polyinosinic-polycytidylic acid (MIA group) or saline (control group) on gestational day 15. Static PET scans of the male offspring were acquired on postnatal day (PND) 21, 60, and 90, using [11C]-PK11195 and deoxy-2-[18F]fluoro-D-glucose ([18F]-FDG) as tracers to measure TSPO expression in activated microglia and brain glucose consumption, respectively. On PND60 and PND90, anxiety-like behaviour, recognition memory, and sensorimotor gating were measured using the open field test (OFT), novel object recognition test (NOR), and prepulse inhibition test (PPI).

RESULTS

[18F]-FDG PET demonstrated that MIA offspring displayed higher brain glucose consumption in the whole brain after weaning (p = 0.017), and in the frontal cortex during late adolescence (p = 0.001) and adulthood (p = 0.037) than control rats. [11C]-PK11195 PET did not reveal any changes in TSPO expression in MIA offspring. Prenatal infection induced age-related behavioural alterations. Adolescent MIA offspring displayed a more anxious state in the OFT than controls (p = 0.042). Adult MIA offspring showed recognition memory deficits in the NOR (p = 0.003). Our study did not show any PPI deficits.

CONCLUSIONS

Our results suggest that prenatal immune activation changed neurodevelopment, resulting in increased brain glucose consumption, but not in microglia activation. The increased brain glucose consumption in the frontal cortex of MIA offspring remained until adulthood and was associated with increased anxiety-like behaviour during adolescence and recognition memory deficits in adulthood.

Brain augmentation and neuroscience technologies: current applications, challenges, ethics and future prospects

Ever since the dawn of antiquity, people have strived to improve their cognitive abilities. From the advent of the wheel to the development of artificial intelligence, technology has had a profound leverage on civilization. Cognitive enhancement or augmentation of brain functions has become a trending topic both in academic and public debates in improving physical and mental abilities. The last years have seen a plethora of suggestions for boosting cognitive functions and biochemical, physical, and behavioral strategies are being explored in the field of cognitive enhancement. Despite expansion of behavioral and biochemical approaches, various physical strategies are known to boost mental abilities in diseased and healthy individuals. Clinical applications of neuroscience technologies offer alternatives to pharmaceutical approaches and devices for diseases that have been fatal, so far. Importantly, the distinctive aspect of these technologies, which shapes their existing and anticipated participation in brain augmentations, is used to compare and contrast them. As a preview of the next two decades of progress in brain augmentation, this article presents a plausible estimation of the many neuroscience technologies, their virtues, demerits, and applications. The review also focuses on the ethical implications and challenges linked to modern neuroscientific technology. There are times when it looks as if ethics discussions are more concerned with the hypothetical than with the factual. We conclude by providing recommendations for potential future studies and development areas, taking into account future advancements in neuroscience innovation for brain enhancement, analyzing historical patterns, considering neuroethics and looking at other related forecasts.

Thalamo-hippocampal dysconnectivity is associated with serum cholesterol level in drug-naïve patients with first-episode schizophrenia

Hippocampal deficits and metabolic dysregulations such as dyslipidemia have been frequently reported in schizophrenia and are suggested to contribute to the pathophysiology of schizophrenia. Hippocampus is particularly susceptible to environmental challenges including metabolism and inflammation. However, evidence linking hippocampal alterations and metabolic dysregulations are quite sparse in drug-naïve schizophrenia. A total of 166 drug-naïve patients with first-episode schizophrenia (FES) and 78 healthy controls (HC) underwent measures for several serum metabolic markers, structural and resting-state functional magnetic resonance imaging (rs-fMRI), as well as diffusion tensor imaging (DTI). Seed-to-voxel functional connectivity (FC) and probabilistic tractography were performed to assess the functional and microstructural connectivity of the bilateral hippocampi. Clinical symptoms were evaluated with Positive and Negative Syndrome Scale (PANSS). Patients with FES showed significantly decreased total cholesterol (Chol) level. Patients showed elevated FC between the left hippocampus and bilateral thalami while showing decreased microstructural connectivity between the left hippocampus and bilateral thalami. Multiple regression analyses showed that FC from the left hippocampus to the right superior frontal gyrus (SFG), bilateral frontal pole (FP), and right thalamus were negatively associated with the Chol level, while no association was observed in the HC group. Our study validated alterations in both functional and microstructural thalamo-hippocampal connectivities, and abnormal cholesterol level in FES. Moreover, decreased cholesterol level is associated with elevated thalamo-hippocampal functional connectivity in patients with FES, suggesting that dyslipidemia may interact with the hippocampal dysfunction in FES.

Abnormal interhemispheric and intrahemispheric functional connectivity dynamics in drug-naïve first-episode schizophrenia patients with auditory verbal hallucinations

Numerous studies indicate altered static local and long‐range functional connectivity of multiple brain regions in schizophrenia patients with auditory verbal hallucinations (AVHs). However, the temporal dynamics of interhemispheric and intrahemispheric functional connectivity patterns remain unknown in schizophrenia patients with AVHs. We analyzed resting‐state functional magnetic resonance imaging data for drug‐naïve first‐episode schizophrenia patients, 50 with AVHs and 50 without AVH (NAVH), and 50 age‐ and sex‐matched healthy controls. Whole‐brain functional connectivity was decomposed into ipsilateral and contralateral parts, and sliding‐window analysis was used to calculate voxel‐wise interhemispheric and intrahemispheric dynamic functional connectivity density (dFCD). Finally, the correlation analysis was performed between abnormal dFCD variance and clinical measures in the AVH and NAVH groups. Compared with the NAVH group and healthy controls, the AVH group showed weaker interhemispheric dFCD variability in the left middle temporal gyrus (p < .01; p < .001), as well as stronger interhemispheric dFCD variability in the right thalamus (p < .001; p < .001) and right inferior temporal gyrus (p < .01; p < .001) and stronger intrahemispheric dFCD variability in the left inferior frontal gyrus (p < .001; p < .01). Moreover, abnormal contralateral dFCD variability of the left middle temporal gyrus correlated with the severity of AVHs in the AVH group (r = −.319, p = .024). The findings demonstrate that abnormal temporal variability of interhemispheric and intrahemispheric dFCD in schizophrenia patients with AVHs mainly focus on the temporal and frontal cortices and thalamus that are pivotal components of auditory and language pathways.

Differences in Cortical Thickness in Schizophrenia Patients With and Without Auditory Verbal Hallucinations

Auditory verbal hallucinations (AVHs) are one of the most common and severe symptoms of schizophrenia (SCZ), but the neuroanatomical mechanisms underlying AVHs remain unclear. This study aimed to investigate whether persistent AVHs (pAVH) are associated with cortical thinning of certain brain regions in patients with SCZ. With the use of the 3T magnetic resonance imaging (MRI) technology, we acquired and analyzed data from 79 SCZ patients with pAVH (pAVH group), 60 SCZ patients without AVHs (non-AVH group), and 83 healthy controls (HC group). The severity of pAVH was assessed by the P3 hallucination items in the Positive and Negative Syndrome Scale (PANSS) and the Auditory Hallucinations Rating Scale (AHRS). Cortical thickness analysis was used to compare the region of interest (ROI) cortical thickness between the groups. The relationship between the severity of pAVH and cortical thickness was also explored. Compared with the non-AVH and HC groups, the pAVH group exhibited significantly reduced cortical thickness in the bilateral lateral orbitofrontal region (p < 0.0007, after Bonferroni correction); no significant difference was found between the non-AVH group and the HC group. The cortical thickness of the left lateral orbitofrontal cortex (P3: r = −0.44, p < 0.001; AHRS: r = −0.45, p < 0.001) and the right lateral orbitofrontal cortex (P3: r = −0.36, p = 0.002; AHRS: r = −0.33, p = 0.004) were negatively correlated with the severity of pAVH (after Bonferroni correction, p < 0.0125). Therefore, abnormal thickness of the bilateral lateral orbitofrontal cortices might be associated with pAVHs in SCZ patients.

Unexpected Consequences of Noise-Induced Hearing Loss: Impaired Hippocampal Neurogenesis, Memory, and Stress

Noise-induced hearing loss (NIHL), caused by direct damage to the cochlea, reduces the flow of auditory information to the central nervous system, depriving higher order structures, such as the hippocampus with vital sensory information needed to carry out complex, higher order functions. Although the hippocampus lies outside the classical auditory pathway, it nevertheless receives acoustic information that influence its activity. Here we review recent results that illustrate how NIHL and other types of cochlear hearing loss disrupt hippocampal function. The hippocampus, which continues to generate new neurons (neurogenesis) in adulthood, plays an important role in spatial navigation, memory, and emotion. The hippocampus, which contains place cells that respond when a subject enters a specific location in the environment, integrates information from multiple sensory systems, including the auditory system, to develop cognitive spatial maps to aid in navigation. Acute exposure to intense noise disrupts the place-specific firing patterns of hippocampal neurons, "spatially disorienting" the cells for days. More traumatic sound exposures that result in permanent NIHL chronically suppresses cell proliferation and neurogenesis in the hippocampus; these structural changes are associated with long-term spatial memory deficits. Hippocampal neurons, which contain numerous glucocorticoid hormone receptors, are part of a complex feedback network connected to the hypothalamic-pituitary (HPA) axis. Chronic exposure to intense intermittent noise results in prolonged stress which can cause a persistent increase in corticosterone, a rodent stress hormone known to suppress neurogenesis. In contrast, a single intense noise exposure sufficient to cause permanent hearing loss produces only a transient increase in corticosterone hormone. Although basal corticosterone levels return to normal after the noise exposure, glucocorticoid receptors (GRs) in the hippocampus remain chronically elevated. Thus, NIHL disrupts negative feedback from the hippocampus to the HPA axis which regulates the release of corticosterone. Preclinical studies suggest that the noise-induced changes in hippocampal place cells, neurogenesis, spatial memory, and glucocorticoid receptors may be ameliorated by therapeutic interventions that reduce oxidative stress and inflammation. These experimental results may provide new insights on why hearing loss is a risk factor for cognitive decline and suggest methods for preventing this decline.

Assessment of treatment resistance criteria in non-invasive brain stimulation studies of schizophrenia

Novel treatment modalities, such as non-invasive brain stimulation (NIBS), typically focus on patient groups that have failed multiple treatment interventions. Despite its promise, the clinical translation of NIBS in schizophrenia has been limited. One important obstacle to implementation is the inconsistent reporting of treatment resistance in the clinical trial literature contributing to heterogeneity in reported effects. In response, we develop a numerical approach to synthesize quality of assessment of Treatment-Resistant Schizophrenia (TRS) and apply this to studies investigating therapeutic response to NIBS in patients with schizophrenia. Literature search conducted through PubMed database identified 119 studies investigating Transcranial Magnetic Stimulation and Transcranial Electrical Stimulation in treating resistant schizophrenia symptoms. A quality score out of 11 was assigned to each study based on adherence to the international consensus guidelines for TRS developed by the Treatment Response and Resistance in Psychosis (TRRIP) group. Results revealed an overall paucity of studies with thorough assessment and/or reporting of TRS phenomenon, as evidenced by a mean quality score of 3.38/11 (SD: 1.01) for trials and 5.16/11 (SD: 1.57) for case reports, though this improved minimally since the publication of consensus criteria. Most studies considered treatment-resistance as a single dimensional construct by reporting resistance of a single symptom, and failed to establish treatment adherence, resistance time course and functional impairment. We conclude that the current NIBS literature in schizophrenia do not reflect its true effects on treatment-resistance. There is an urgent need to improve assessment and reporting standards of clinical trials that target TRS.

More than Addiction—The Nucleus Accumbens Contribution to Development of Mental Disorders and Neurodegenerative Diseases

Stress and negative emotions evoked by social relationships and working conditions, frequently accompanied by the consumption of addictive substances, and metabolic and/or genetic predispositions, negatively affect brain function. One of the affected structures is nucleus accumbens (NAc). Although its function is commonly known to be associated with brain reword responses and addiction, a growing body of evidence also suggests its role in some mental disorders, such as depression and schizophrenia, as well as neurodegenerative diseases, such as Alzheimer’s, Huntington’s, and Parkinson’s. This may result from disintegration of the extensive connections based on numerous neurotransmitter systems, as well as impairment of some neuroplasticity mechanisms in the NAc. The consequences of NAc lesions are both morphological and functional. They include changes in the NAc’s volume, cell number, modifications of the neuronal dendritic tree and dendritic spines, and changes in the number of synapses. Alterations in the synaptic plasticity affect the efficiency of synaptic transmission. Modification of the number and structure of the receptors affects signaling pathways, the content of neuromodulators (e.g., BDNF) and transcription factors (e.g., pCREB, DeltaFosB, NFκB), and gene expression. Interestingly, changes in the NAc often have a different character and intensity compared to the changes observed in the other parts of the basal ganglia, in particular the dorsal striatum. In this review, we highlight the role of the NAc in various pathological processes in the context of its structural and functional damage, impaired connections with the other brain areas cooperating within functional systems, and progression of the pathological processes.

Psychiatric symptoms of frontotemporal dementia and subcortical (co-)pathology burden: new insights

Three subtypes of distinct pathological proteins accumulate throughout multiple brain regions and shape the heterogeneous clinical presentation of frontotemporal lobar degeneration (FTLD). Besides the main pathological subtypes, co-occurring pathologies are common in FTLD brain donors. The objective of this study was to investigate how the location and burden of (co-)pathology correlate to early psychiatric and behavioural symptoms of FTLD. Eighty-seven brain donors from The Netherlands Brain Bank cohort (2008-2017) diagnosed with FTLD were included: 46 FTLD-TAR DNA-binding protein 43 (FTLD-TDP), 34 FTLD-tau, and seven FTLD-fused-in-sarcoma (FTLD-FUS). Post-mortem brain tissue was dissected into 20 standard regions and stained for phosphorylated TDP-43, phosphorylated tau, FUS, amyloid-β, and α-synuclein. The burden of each pathological protein in each brain region was assessed with a semi-quantitative score. Clinical records were reviewed for early psychiatric and behavioural symptoms. Whole-brain clinico-pathological partial correlations were calculated (local false discovery rate threshold = 0.01). Elaborating on the results, we validated one finding using a quantitative assessment of TDP-43 pathology in the granular layer of the hippocampus in FTLD-TDP brain donors with (n = 15) and without (n = 15) hallucinations. In subcortical regions, the presence of psychiatric symptoms showed positive correlations with increased hippocampal pathology burden: hallucinations with TDP-43 in the granular layer (R = 0.33), mania with TDP-43 in CA1 (R = 0.35), depression with TDP-43 in CA3 and with parahippocampal tau (R = 0.30 and R = 0.23), and delusions with CA3 tau (R = 0.26) and subicular amyloid-β (R = 0.25). Behavioural disinhibition showed positive correlations with tau burden in the thalamus (R = 0.29) and with both TDP-43 and amyloid-β burden in the subthalamus (R = 0.23 and R = 0.24). In the brainstem, the presence of α-synuclein co-pathology in the substantia nigra correlated with disinhibition (R = 0.24), tau pathology in the substantia nigra correlated with depression (R = 0.25) and in the locus coeruleus with both depression and perseverative/compulsive behaviour (R = 0.26 and R = 0.32). The quantitative assessment of TDP-43 in the granular layer validated the higher burden of TDP-43 pathology in brain donors with hallucinations compared to those without hallucinations (P = 0.007). Our results show that psychiatric symptoms of FTLD are linked to subcortical pathology burden in the hippocampus, and hallucinations are linked to a higher burden of TDP-43 in the granular layer. Co-occurring non-FTLD pathologies in subcortical regions could contribute to configuring the clinical phenotype of FTLD.

Ventral Striatal-Hippocampus Coupling During Reward Processing as a Stratification Biomarker for Psychotic Disorders

BACKGROUND

Altered ventral striatal (vST) activation to reward expectancy is a well-established intermediate phenotype for psychiatric disorders, specifically schizophrenia (SZ). Preclinical research suggests that striatal alterations are related to a reduced inhibition by the hippocampal formation, but its role in human transdiagnostic reward-network dysfunctions is not well understood.

METHODS

We performed functional magnetic resonance imaging during reward processing in 728 individuals including healthy control subjects (n = 396), patients (SZ: n = 46; bipolar disorder: n = 45; major depressive disorder: n = 60), and unaffected first-degree relatives (SZ: n = 46; bipolar disorder: n = 50; major depressive disorder: n = 85). We assessed disorder-specific differences in functional vST-hippocampus coupling and transdiagnostic associations with dimensional measures of positive, negative, and cognitive symptoms. We also probed the genetic underpinning using polygenic risk scores for SZ in a subset of healthy participants (n = 295).

RESULTS

Functional vST-hippocampus coupling was 1) reduced in patients with SZ and bipolar disorder (p_FWE < .05, small-volume corrected [SVC]); 2) associated transdiagnostically to dimensional measures of positive (p_FWE = .01, SVC) and cognitive (p_FWE = .02, SVC), but not negative, (p_FWE > .05, SVC) symptoms; and 3) reduced in first-degree relatives of patients with SZ (p_FWE = .017, SVC) and linked to the genetic risk for SZ in healthy participants (p = .035).

CONCLUSIONS

We provide evidence that reduced vST-hippocampus coupling during reward processing is an endophenotype for SZ linked to positive and cognitive symptoms, supporting current preclinical models of the emergence of psychosis. Moreover, our data indicate that vST-hippocampus coupling is familial and linked to polygenic scores for SZ, supporting the use of this measure as an intermediate phenotype for psychotic disorders.

Real-Time Symptom Capture of Hallucinations in Schizophrenia with fMRI: Absence of Duration-Dependent Activity

Background

While advances in the field of functional magnetic resonance imaging (fMRI) provide new opportunities to study brain networks underlying the experience of hallucinations in psychosis, there are methodological challenges unique to symptom-capture studies.

Study Design

We extracted brain networks activated during hallucination-capture for schizophrenia patients when fMRI data collected from two sites was merged (combined N = 27). A multidimensional analysis technique was applied, which would allow separation of brain networks involved in the hallucinatory experience itself from those involved in the motor response of indicating the beginning and end of the perceived hallucinatory experience. To avoid reverse inference when attributing a function (e.g., a hallucination) to anatomical regions, it was required that longer hallucinatory experiences produce extended brain responses relative to shorter.

Study Results

For radio-speech sound files, an auditory perception brain network emerged, and displayed speech-duration-dependent hemodynamic responses (HDRs). However, in the hallucination-capture blocks, no network showed hallucination-duration-dependent HDRs, but a retrieved network that was anatomically classified as motor response emerged.

Conclusions

During symptom capture of hallucinations during fMRI, no HDR showed duration dependence, but a brain network anatomically matching the motor response network was retrieved. Previous reports on brain networks detected by fMRI during hallucination capture are reviewed in this context; namely, that the brain networks interpreted as involved in hallucinations may in fact be involved only in the motor response indicating the onset of the hallucination.

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.

A Case for Thalamic Mechanisms of Schizophrenia: Perspective From Modeling 22q11.2 Deletion Syndrome

Schizophrenia is a severe, chronic psychiatric disorder that devastates the lives of millions of people worldwide. The disease is characterized by a constellation of symptoms, ranging from cognitive deficits, to social withdrawal, to hallucinations. Despite decades of research, our understanding of the neurobiology of the disease, specifically the neural circuits underlying schizophrenia symptoms, is still in the early stages. Consequently, the development of therapies continues to be stagnant, and overall prognosis is poor. The main obstacle to improving the treatment of schizophrenia is its multicausal, polygenic etiology, which is difficult to model. Clinical observations and the emergence of preclinical models of rare but well-defined genomic lesions that confer substantial risk of schizophrenia (e.g., 22q11.2 microdeletion) have highlighted the role of the thalamus in the disease. Here we review the literature on the molecular, cellular, and circuitry findings in schizophrenia and discuss the leading theories in the field, which point to abnormalities within the thalamus as potential pathogenic mechanisms of schizophrenia. We posit that synaptic dysfunction and oscillatory abnormalities in neural circuits involving projections from and within the thalamus, with a focus on the thalamocortical circuits, may underlie the psychotic (and possibly other) symptoms of schizophrenia.

The Perspectives of Early Diagnosis of Schizophrenia Through the Detection of Epigenomics-Based Biomarkers in iPSC-Derived Neurons

The lack of early diagnostic biomarkers for schizophrenia greatly limits treatment options that deliver therapeutic agents to affected cells at a timely manner. While previous schizophrenia biomarker research has identified various biological signals that are correlated with certain diseases, their reliability and practicality as an early diagnostic tool remains unclear. In this article, we discuss the use of atypical epigenetic and/or consequent transcriptional alterations (ETAs) as biomarkers of early-stage schizophrenia. Furthermore, we review the viability of discovering and applying these biomarkers through the use of cutting-edge technologies such as human induced pluripotent stem cell (iPSC)-derived neurons, brain models, and single-cell level analyses.

Auditory hallucinations across the psychosis spectrum: Evidence of dysconnectivity involving cerebellar and temporal lobe regions

BACKGROUND

Auditory hallucinations (AH) are typically associated with schizophrenia (SZ), but they are also prevalent in bipolar disorder (BD). Despite the large body of research on the neural correlates of AH in SZ, the pathophysiology underlying AH remains unclear. Few studies have examined the neural substrates associated with propensity for AH in BD. Investigating AH across the psychosis spectrum has the potential to inform about the neural signature associated with the trait of AH, irrespective of psychiatric diagnosis.

METHODS

We compared resting state functional magnetic resonance imaging data in psychosis patients with (n = 90 AH; 68 SZ, 22 BD) and without (n = 55 NAH; 16 SZ, 39 BD) lifetime AH. We performed region of interest (ROI)-to-ROI functional connectivity (FC) analysis using 91 cortical, 15 subcortical, and 26 cerebellar atlas-defined regions. The primary aim was to identify FC differences between patients with and without lifetime AH. We secondarily examined differences between AH and NAH within each diagnosis.

RESULTS

Compared to the NAH group, patients with AH showed higher FC between cerebellum and frontal (left precentral gyrus), temporal [right middle temporal gyrus (MTG), left inferior temporal gyrus (ITG), left temporal fusiform gyrus)], parietal (bilateral superior parietal lobules), and subcortical (left accumbens, left palldium) brain areas. AH also showed lower FC between temporal lobe regions (between right ITG and right MTG and bilateral superior temporal gyri) relative to NAH.

CONCLUSIONS

Our findings suggest that dysconnectivity involving the cerebellum and temporal lobe regions may be common neurofunctional elements associated with AH propensity across the psychosis spectrum. We also found dysconnectivity patterns that were unique to lifetime AH within SZ or bipolar psychosis, suggesting both common and distinct mechanisms underlying AH pathophysiology in these disorders.

A review of functional and structural neuroimaging studies to investigate the inner speech model of auditory verbal hallucinations in schizophrenia

Although the pathophysiology of auditory verbal hallucinations remains uncertain, the inner speech model remains a prominent theory. A systematic review and meta-analyses of both functional and structural neuroimaging studies were performed to investigate the inner speech model. Of the 417 papers retrieved, 26 met the inclusion criteria. Meta-analyses found the left insula to be significantly active during auditory verbal hallucinations and to have a significantly reduced grey matter volume in hallucinators. Dysfunction of the left insula may contribute to the misattribution of inner speech due to its suggested roles in both inner speech production and the salience network. No significant activity was found at Broca's area or Heschl's gyrus during auditory verbal hallucinations. Furthermore, no structural abnormalities were found at these sites or in the arcuate fasciculi. Overall, evidence was found to both support and oppose the inner speech model. Further research should particularly include a systematic review of task-based trait studies with a focus on inner speech production and self-referential processing, and analyses of additional language-related white matter tracts.

A systematic review of the neural correlates of multisensory integration in schizophrenia

Multisensory integration (MSI), in which sensory signals from different modalities are unified, is necessary for our comprehensive perception of and effective adaptation to the objects and events around us. However, individuals with schizophrenia suffer from impairments in MSI, which could explain typical symptoms like hallucination and reality distortion. Because the neural correlates of aberrant MSI in schizophrenia help us understand the physiognomy of this psychiatric disorder, we performed a systematic review of the current research on this subject. The literature search concerned investigated MSI in diagnosed schizophrenia patients compared to healthy controls using brain imaging. Seventeen of 317 identified studies were finally included. To assess risk of bias, the Newcastle-Ottawa quality assessment was used, and the review was written according to the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA). The results indicated that multisensory processes in schizophrenia are associated with aberrant, mainly reduced, neural activity in several brain regions, as measured by event-related potentials, oscillations, activity and connectivity. The conclusion is that a fronto-temporal region, comprising the frontal inferior gyrus, middle temporal gyrus and superior temporal gyrus/sulcus, along with the fusiform gyrus and dorsal visual stream in the occipital-parietal lobe are possible key regions of deficient MSI in schizophrenia.

Successful suppression of musical hallucinations with low-frequency rTMS of the left temporo-parietal junction: A case report

BACKGROUND

Inhibitory low frequency repetitive transcranial magnetic stimulation (rTMS) of the temporo-parietal area has been applied to treat both auditory verbal hallucinations as well as tinnitus.

OBJECTIVE

We hypothesized that 1 Hz rTMS to the left temporoparietal junction (TPJ) may be beneficial in alleviating musical hallucinations (MH), another condition with auditory experiences in the absence of an external source.

METHODS

Here we describe a patient with almost insufferable life-long MH with comorbid depression, who received inhibitory rTMS to the left TPJ as well as the right dorsolateral prefrontal cortex (DLPFC).

RESULTS

The intrusiveness and frequency of her MH as well as her depressive symptoms alleviated quickly and substantially, and once-a-week maintenance therapy with rTMS seemed to preserve this amelioration. Future studies will hopefully reveal whether this is a viable treatment approach for other patients suffering from MH with or without comorbid depression.

Auditory hallucinations activate language and verbal short-term memory, but not auditory, brain regions

Auditory verbal hallucinations (AVH, ‘hearing voices’) are an important symptom of schizophrenia but their biological basis is not well understood. One longstanding approach proposes that they are perceptual in nature, specifically that they reflect spontaneous abnormal neuronal activity in the auditory cortex, perhaps with additional ‘top down’ cognitive influences. Functional imaging studies employing the symptom capture technique—where activity when patients experience AVH is compared to times when they do not—have had mixed findings as to whether the auditory cortex is activated. Here, using a novel variant of the symptom capture technique, we show that the experience of AVH does not induce auditory cortex activation, even while real speech does, something that effectively rules out all theories that propose a perceptual component to AVH. Instead, we find that the experience of AVH activates language regions and/or regions that are engaged during verbal short-term memory.