Dysfunctional cortico-cerebellar circuits cause 'cognitive dysmetria' in schizophrenia

The interaction effect of high social support and resilience on functional connectivity using seed-based resting-state assessed by 7-Tesla ultra-high field MRI

Recent resilience research has increasingly emphasized the importance of focusing on investigating the protective factors in mentally healthy populations, complementing the traditional focus on psychopathology. Social support has emerged as a crucial element within the complex interplay of individual and socio-environmental factors that shape resilience. However, the neural underpinnings of the relationship between social support and resilience, particularly in healthy subjects, remain largely unexplored. With advances in neuroimaging techniques, such as ultra-high field MRI at 7T and beyond, researchers can more effectively investigate the neural mechanisms underlying these factors. Thus, our study employed ultra-high field rs-fMRI to explore how social support moderates the relationship between psychological resilience and functional connectivity in a healthy cohort. We hypothesized that enhanced social support would amplify resilience-associated connectivity within neural circuits essential for emotional regulation, cognitive processing, and adaptive problem-solving, signifying a synergistic interaction where strong social networks bolster the neural underpinnings of resilience. (n = 30). Through seed-based functional connectivity analyses and interaction analysis, we aimed to uncover the neural correlates at the interplay of social support and resilience. Our findings indicate that perceived social support significantly (p<0.001) alters functional connectivity in the right and left FP, PCC, and left hippocampus, affirming the pivotal roles of these regions in the brain's resilience network. Moreover, we identified significant moderation effects of social support across various brain regions, each showing unique connectivity patterns. Specifically, the right FP demonstrated a significant interaction effect where high social support levels were linked to increased connectivity with regions involved in socio-cognitive processing, while low social support showed opposite effects. Similar patterns by social support levels were observed in the left FP, with connectivity changes in clusters associated with emotional regulation and cognitive functions. The PCC's connectivity was distinctly influenced by support levels, elucidating its role in emotional and social cognition. Interestingly, the connectivity of the left hippocampus was not significantly impacted by social support levels, indicating a unique pattern within this region. These insights highlight the importance of high social support levels in enhancing the neural foundations of resilience and fostering adaptive neurological responses to environmental challenges.

Clinical anatomy of the precuneus and pathogenesis of the schizophrenia

Recent evidence has shown that the precuneus plays a role in the pathogenesis of schizophrenia. The precuneus is a structure of the parietal lobe's medial and posterior cortex, representing a central hub involved in multimodal integration processes. Although neglected for several years, the precuneus is highly complex and crucial for multimodal integration. It has extensive connections with different cerebral areas and is an interface between external stimuli and internal representations. In human evolution, the precuneus has increased in size and complexity, allowing the development of higher cognitive functions, such as visual-spatial ability, mental imagery, episodic memory, and other tasks involved in emotional processing and mentalization. This paper reviews the functions of the precuneus and discusses them concerning the psychopathological aspects of schizophrenia. The different neuronal circuits, such as the default mode network (DMN), in which the precuneus is involved and its alterations in the structure (grey matter) and the disconnection of pathways (white matter) are described.

Progress in sensorimotor neuroscience of schizophrenia spectrum disorders: Lessons learned and future directions

The number of neuroimaging studies on movement disorders, sensorimotor, and psychomotor functioning in schizophrenia spectrum disorders (SSD) has steadily increased over the last two decades. Accelerated by the addition of the "sensorimotor domain" to the Research Domain Criteria (RDoC) framework in January 2019, neuroscience research on the role of sensorimotor dysfunction in SSD has gained greater scientific and clinical relevance. To draw attention to recent rapid progress in the field, we performed a triennial systematic review (PubMed search from January 1st^, 2018 through December 31st^, 2020), in which we highlight recent neuroimaging findings and discuss methodological pitfalls as well as challenges for future research. The identified magnetic resonance imaging (MRI) studies suggest that sensorimotor abnormalities in SSD are related to cerebello-thalamo-cortico-cerebellar network dysfunction. Longitudinal and interventional studies highlight the translational potential of the sensorimotor domain as putative biomarkers for treatment response and as targets for non-invasive neurostimulation techniques in SSD.

Lower functional connectivity of white matter during rest and working memory tasks is associated with cognitive impairments in schizophrenia

BACKGROUND

Schizophrenia can be understood as a disturbance of functional connections within brain networks. However, functional alterations that involve white matter (WM) specifically, or their cognitive correlates, have seldomly been investigated, especially during tasks.

METHODS

Resting state and task fMRI images were acquired on 84 patients and 67 controls. Functional connectivities (FC) between 46 WM bundles and 82 cortical regions were compared between the groups under two conditions (i.e., resting state and during working memory retention period). The FC density of each WM bundle was then compared between groups. Associations of FC with cognitive scores were evaluated.

RESULTS

FC measures were lower in schizophrenia relative to controls for external capsule, cingulum (cingulate and hippocampus), uncinate fasciculus, as well as corpus callosum (genu and body) under the rest or the task condition, and were higher in the posterior corona radiata and posterior thalamic radiation during the task condition. FC for specific WM bundles was correlated with cognitive performance assessed by working memory and processing speed metrics.

CONCLUSIONS

The findings suggest that the functional abnormalities in patients' WM are heterogeneous, possibly reflecting several underlying mechanisms such as structural damage, functional compensation and excessive effort on task, and that WM FC disruption may contribute to the impairments of working memory and processing speed. This is the first report on WM FC abnormalities in schizophrenia relative to controls and their cognitive associates during both rest and task and highlights the need to consider WM functions as components of brain functional networks in schizophrenia.

Postural Control and Verbal and Visual Working Memory Correlates in Nonclinical Psychosis

INTRODUCTION

Motor and cognitive abnormalities are well documented in psychosis spectrum disorders. Evidence suggests these deficits could be pronounced because of disruptions in the cerebellar-thalamic-cortical-cerebellar (CTCC) circuit, a network thought to be heavily implicated in motor and higher cognitive functioning. Although significant research has been done on this topic in individuals with schizophrenia and those at a clinical high risk for psychosis, much less is known about deficits at the lower end of the spectrum.

METHODS

In this study, we extended the understanding of motor abnormalities across the psychosis continuum by examining postural sway deficits in the nonclinical psychosis (NCP) population. Furthermore, we linked these deficits to verbal and visual working memory. High-NCP (n = 37) and low-NCP control (n = 31) participants completed an instrumental balance task, highly sensitive to subtle variations in postural sway, along with a brief working memory battery.

RESULTS

We found that high-NCP participants presented with increased postural sway area (i.e., worse postural control) relative to low-NCP controls on a difficult condition (with limited proprioceptive cues), but not on an easier condition. Furthermore, results indicated that the sway area was correlated with poorer performance on working memory tasks in the high-NCP group.

CONCLUSION

These findings suggest that CTCC circuit abnormalities are present across the lower end of the psychosis spectrum and that they may be contributing to a range of motor and cognitive behaviors seen in the population. However, evidence suggests that the signs are subtle, and that sensitive assessment devices and challenging conditions may be necessary for detection.

Effectiveness of Cerebellar Circuitry Modulation in Schizophrenia: A Systematic Review

Structural and functional abnormalities of the cerebellum have been observed in schizophrenia since the first neuroimaging studies. More recently, the functions of the cerebellum have been extended beyond sensorimotor control to include participation in higher-level cognition and affective regulation. Consistently, the "cognitive dysmetria" theory posits that dysfunctions of cortical-subcortical-cerebellar circuitry may be crucial for the pathogenesis of different clinical features of schizophrenia. This conceptual framework offers a set of testable hypotheses, now that various tools to exert direct modulation of cerebellar activity are available. We conducted a systematic review of studies examining the effects of cerebellar modulation in schizophrenia. Two independent authors conducted a search within PubMed for articles published up to April 2019 and identified 10 studies (three randomized controlled trials, two open-label studies, two case reports, one preclinical study) describing the effects of cerebellar circuitry modulation in patients with schizophrenia or animal models. The majority of interventions were uncontrolled and used stimulation of the cerebellar vermis, using transcranial magnetic stimulation or transcranial direct-current stimulation. Most studies detected improvements after cerebellar modulation. Clinical changes mostly pertained the domains of negative symptoms, depressive symptoms and cognitive functions. In conclusion, few studies examined the effects of cerebellar modulation in schizophrenia but yielded promising results. This approach may hold therapeutic potential, pending further methodologically robust replication.

Cerebello-thalamo-cortical hyperconnectivity as a state-independent functional neural signature for psychosis prediction and characterization

Understanding the fundamental alterations in brain functioning that lead to psychotic disorders remains a major challenge in clinical neuroscience. In particular, it is unknown whether any state-independent biomarkers can potentially predict the onset of psychosis and distinguish patients from healthy controls, regardless of paradigm. Here, using multi-paradigm fMRI data from the North American Prodrome Longitudinal Study consortium, we show that individuals at clinical high risk for psychosis display an intrinsic “trait-like” abnormality in brain architecture characterized as increased connectivity in the cerebello–thalamo–cortical circuitry, a pattern that is significantly more pronounced among converters compared with non-converters. This alteration is significantly correlated with disorganization symptoms and predictive of time to conversion to psychosis. Moreover, using an independent clinical sample, we demonstrate that this hyperconnectivity pattern is reliably detected and specifically present in patients with schizophrenia. These findings implicate cerebello–thalamo–cortical hyperconnectivity as a robust state-independent neural signature for psychosis prediction and characterization.

Brain function alterations in schizophrenia and other psychotic disorders remain poorly understood. Here, the authors discover that increased neural connectivity in the cerebello-thalamo-cortical circuitry predicts psychosis in those at high risk, and is present in people with schizophrenia.

Objective and quantitative equilibriometric evaluation of individual locomotor behaviour in schizophrenia: Translational and clinical implications

Psychiatry is the only medical specialty that lacks clinically applicable biomarkers for objective evaluation of the existing pathology at a single-patient level. On the basis of an original translational equilibriometric method for evaluation of movement patterns, we have introduced in the everyday clinical practice of psychiatry an easy-to-perform computerized objective quantification of the individual locomotor behaviour during execution of the Unterberger stepping test. For the last 20 years, we have gradually collected a large database of more than 1000 schizophrenic patients, their relatives, and matched psychiatric, neurological, and healthy controls via cross-sectional and longitudinal investigations. Comparative analyses revealed transdiagnostic locomotor similarities among schizophrenic patients, high-risk schizotaxic individuals, and neurological patients with multiple sclerosis and cerebellar ataxia, thus suggesting common underlying brain mechanisms. In parallel, intradiagnostic dissimilarities were revealed, which allow to separate out subclinical locomotor subgroups within the diagnostic categories. Prototypical qualitative (dysmetric and ataxic) locomotor abnormalities in schizophrenic patients were differentiated from 2 atypical quantitative ones, manifested as either hypolocomotion or hyperlocomotion. Theoretical analyses suggested that these 3 subtypes of locomotor abnormalities could be conceived as objectively measurable biomarkers of 3 schizophrenic subgroups with dissimilar brain mechanisms, which require different treatment strategies. Analogies with the prominent role of locomotor measures in some well-known animal models of mental disorders advocate for a promising objective translational research in the so far over-subjective field of psychiatry. Distinctions among prototypical, atypical, and diagnostic biomarkers, as well as between neuromotor and psychomotor locomotor abnormalities, are discussed. Conclusions are drawn about the translational and clinical implications of the new approach and its future perspectives.

Cognitive and psychopathology correlates of brain white/grey matter structure in severely psychotic schizophrenic inpatients

The brain structural correlates of cognitive and psychopathological symptoms within the active phase in severely psychotic schizophrenic inpatients have been rarely investigated. Twenty-eight inpatients with a DSM-5 diagnosis of Schizophrenia (SZ), admitted for acute psychotic decompensation, were assessed through a comprehensive neuropsychological and psychopathological battery. All patients underwent a high-resolution T1-weighted magnetic resonance imaging investigation. Increased psychotic severity was related to reduced grey matter volumes in the medial portion of the right superior frontal cortex, the superior orbitofrontal cortex bilaterally and to white matter volume reduction in the medial portion of the left superior frontal area. Immediate verbal memory performance was related to left insula and inferior parietal cortex volume, while long-term visuo-spatial memory was related to grey matter volume of the right middle temporal cortex, and the right (lobule VII, CRUS1) and left (lobule VI) cerebellum. Moreover, psychotic severity correlated with cognitive inflexibility and negative symptom severity was related to visuo-spatial processing and reasoning disturbances. These findings indicate that a disruption of the cortical-subcortical-cerebellar circuit, and distorted memory function contribute to the development and maintenance of psychotic exacerbation.

Top-Down Disconnectivity in Schizophrenia During P300 Tasks

Cognitive deficits in schizophrenia are correlated with the dysfunctions of distinct brain regions including anterior cingulate cortex (ACC) and prefrontal cortex (PFC). Apart from the dysfunctions of the intrinsic connectivity of related areas, how the coupled neural populations work is also crucial in related processes. Twenty-four patients with schizophrenia (SZs) and 24 matched healthy controls (HCs) were recruited in our study. Based on the electroencephalogram (EEG) datasets recorded, the Dynamic Causal Modeling (DCM) was then adopted to estimate how the brain architecture adapts among related areas in SZs and to investigate the mechanism that accounts for their cognitive deficits. The distinct winning models in SZs and HCs consistently emphasized the importance of ACC in regulating the elicitations of P300s. Specifically, comparing to that in HCs, the winning model in SZs uncovered a compensatory pathway from dorsolateral PFC to intraparietal sulcus that promised the SZs' accomplishing P300 tasks. The findings demonstrated that the “disconnectivity hypothesis” is helpful and useful in explaining the cognitive deficits in SZs, while the brain architecture adapted with related compensatory pathway promises the limited brain cognitions in SZs. This study provides a new viewpoint that deepens our understanding of the cognitive deficits in schizophrenia.

Topography of the cerebellum in relation to social brain regions and emotions

In the last few decades, an increasing number of studies have focused on better characterizing the cerebellar functions beyond motor control, including emotional and social domains. Anatomic and functional evidence strongly contributes to delineating the cerebellar functional subdivisions and their integration with cerebral functional networks strictly related to emotional regulation and social functioning, thus suggesting a model of cerebellar organization that resembles that of the cerebral cortex. Overcoming the traditional segregation of cerebrocerebellar networks in sensorimotor/cognitive functional modules, during emotional/social processes, the cerebellar activity reflects a domain-specific mentalizing functionality that is strongly connected with corresponding mentalizing networks in the cerebrum. Additionally, the cerebrocerebellar organization has been shown to have a specific functional and maturational trajectory that is only in part dependent on a structural maturational process and that is protracted from an early stage of life through adolescence and adulthood, when the mature control networks involve both segregation and integration of the brain regions that comprise them. Altogether, these findings underscore the importance of regional functional differences within the cerebellum in relation to emotional and social processing and raise questions about the clinical implication of cerebellar injury on emotional/social behaviors, both in the developing and the adult brain.

What Can Different Motor Circuits Tell Us About Psychosis? An RDoC Perspective

Signs of motor dysfunction are evidenced across a range of psychiatric disorders including schizophrenia. Historically, these features have been neglected but emerging theoretical and methodological advancements have shed new light on the utility of considering movement abnormalities. Indeed, the National Institute of Mental Health Research Domain Criteria initiative has recently met to develop a Motor Systems Domain. This reflects a growing appreciation for the enhanced reliability and validity that can come along with evaluating disturbances relevant to psychiatric illnesses from multiple levels of analysis, and conceptualizing these domains with respect to the complexity of their role in a broader integrated system (ie, weighing contributions and interactions between the cognitive, affective, and motor domains). This article discusses motor behaviors and seeks to explain how research into basal ganglia, cerebellar, and cortico-motor circuit function/dysfunction, grounded in brain circuit-motor behavior relationships, can elucidate our understanding of pathophysiology, provide vital links to other key systems of interest, significantly improve identification and classification, and drive development of targeted individualized treatments.

Functional neuroanatomical correlates of episodic memory impairment in early phase psychosis

Studies have demonstrated that episodic memory (EM) is often preferentially disrupted in schizophrenia. The neural substrates that mediate EM impairment in this illness are not fully understood. Several functional magnetic resonance imaging (fMRI) studies have employed EM probe tasks to elucidate the neural underpinnings of impairment, though results have been inconsistent. The majority of EM imaging studies have been conducted in chronic forms of schizophrenia with relatively few studies in early phase patients. Early phase schizophrenia studies are important because they may provide information regarding when EM deficits occur and address potential confounds more frequently observed in chronic populations. In this study, we assessed brain activation during the performance of visual scene encoding and recognition fMRI tasks in patients with earlyphase psychosis (n = 35) and age, sex, and race matched healthy control subjects (n = 20). Patients demonstrated significantly lower activation than controls in the right hippocampus and left fusiform gyrus during scene encoding and lower activation in the posterior cingulate, precuneus, and left middle temporal cortex during recognition of target scenes. Symptom levels were not related to the imaging findings, though better cognitive performance in patients was associated with greater right hippocampal activation during encoding. These results provide evidence of altered function in neuroanatomical circuitry subserving EM early in the course of psychotic illness, which may have implications for pathophysiological models of this illness.

Dysfluent Handwriting in Schizophrenic Outpatients

Taking into account findings in the literature, the author aimed to test whether specific graphical characteristics of handwriting can distinguish patients diagnosed with schizophrenic disorders from healthy controls. Handwriting samples (one sample from each person) from 60 outpatients (29 women, 31 men; age M = 28.5, SD = 5.4) with paranoid schizophrenia were analyzed by three documents examiners and were compared to samples from 60 controls (30 men, 30 women, age M = 28.0, SD = 3.0) without psychiatric disorders. Document examiners assessed 32 graphical features potentially related to schizophrenia. The comparisons between groups revealed that only 7 out of 32 handwriting properties were significantly different in the handwriting of schizophrenic outpatients from controls: the calligraphic forms of letters, loops in ovals, lacking of dots, tremor, sinusoidal baseline, and irregularities size of lower zone. These findings are discussed in terms of motor disturbances in schizophrenia and in relation to the previous research on handwriting of other mental disorders. Similarities between the graphical patterns of handwriting of schizophrenic patients and those of other mental disorders and/or other mental states have been demonstrated.

Association of serum VEGF levels with prefrontal cortex volume in schizophrenia

A large body of evidence indicates alterations in brain regional cellular energy metabolism and blood flow in schizophrenia. Among the different molecules regulating blood flow, vascular endothelial growth factor (VEGF) is generally accepted as the major factor involved in the process of angiogenesis. In the present study, we examined whether peripheral VEGF levels correlate with changes in the prefrontal cortex (PFC) volume in patients with schizophrenia and in healthy controls. Whole-blood samples were obtained from 96 people with schizophrenia or schizoaffective disorder and 83 healthy controls. Serum VEGF protein levels were analyzed by enzyme-linked immunosorbent assay, whereas quantitative PCR was performed to measure interleukin-6 (IL-6, a pro-inflammatory marker implicated in schizophrenia) mRNA levels in the blood samples. Structural magnetic resonance imaging scans were obtained using a 3T Achieva scanner on a subset of 59 people with schizophrenia or schizoaffective disorder and 65 healthy controls, and prefrontal volumes were obtained using FreeSurfer software. As compared with healthy controls, individuals with schizophrenia had a significant increase in log-transformed mean serum VEGF levels (t(177)=2.9, P=0.005). A significant inverse correlation (r=-0.40, P=0.002) between serum VEGF and total frontal pole volume was found in patients with schizophrenia/schizoaffective disorder. Moreover, we observed a significant positive association (r=0.24, P=0.03) between serum VEGF and IL-6 mRNA levels in patients with schizophrenia. These findings suggest an association between serum VEGF and inflammation, and that serum VEGF levels are related to structural abnormalities in the PFC of people with schizophrenia.

Cellular commitment in the developing cerebellum

The mammalian cerebellum is located in the posterior cranial fossa and is critical for motor coordination and non-motor functions including cognitive and emotional processes. The anatomical structure of cerebellum is distinct with a three-layered cortex. During development, neurogenesis and fate decisions of cerebellar primordium cells are orchestrated through tightly controlled molecular events involving multiple genetic pathways. In this review, we will highlight the anatomical structure of human and mouse cerebellum, the cellular composition of developing cerebellum, and the underlying gene expression programs involved in cell fate commitments in the cerebellum. A critical evaluation of the cell death literature suggests that apoptosis occurs in ~5% of cerebellar cells, most shortly after mitosis. Apoptosis and cellular autophagy likely play significant roles in cerebellar development, we provide a comprehensive discussion of their role in cerebellar development and organization. We also address the possible function of unfolded protein response in regulation of cerebellar neurogenesis. We discuss recent advancements in understanding the epigenetic signature of cerebellar compartments and possible connections between DNA methylation, microRNAs and cerebellar neurodegeneration. Finally, we discuss genetic diseases associated with cerebellar dysfunction and their role in the aging cerebellum.

Large-Scale Fusion of Gray Matter and Resting-State Functional MRI Reveals Common and Distinct Biological Markers across the Psychosis Spectrum in the B-SNIP Cohort

To investigate whether aberrant interactions between brain structure and function present similarly or differently across probands with psychotic illnesses [schizophrenia (SZ), schizoaffective disorder (SAD), and bipolar I disorder with psychosis (BP)] and whether these deficits are shared with their first-degree non-psychotic relatives. A total of 1199 subjects were assessed, including 220 SZ, 147 SAD, 180 psychotic BP, 150 first-degree relatives of SZ, 126 SAD relatives, 134 BP relatives, and 242 healthy controls (1). All subjects underwent structural MRI (sMRI) and resting-state functional MRI (rs-fMRI) scanning. Joint-independent component analysis (jICA) was used to fuse sMRI gray matter and rs-fMRI amplitude of low-frequency fluctuations data to identify the relationship between the two modalities. jICA revealed two significantly fused components. The association between functional brain alteration in a prefrontal-striatal-thalamic-cerebellar network and structural abnormalities in the default mode network was found to be common across psychotic diagnoses and correlated with cognitive function, social function, and schizo-bipolar scale scores. The fused alteration in the temporal lobe was unique to SZ and SAD. The above effects were not seen in any relative group (including those with cluster-A personality). Using a multivariate-fused approach involving two widely used imaging markers, we demonstrate both shared and distinct biological traits across the psychosis spectrum. Furthermore, our results suggest that the above traits are psychosis biomarkers rather than endophenotypes.

The therapeutic potential of the cerebellum in schizophrenia

The cognitive role of the cerebellum is critically tied to its distributed connections throughout the brain. Accumulating evidence from anatomical, structural and functional imaging, and lesion studies advocate a cognitive network involving indirect connections between the cerebellum and non-motor areas in the prefrontal cortex. Cerebellar stimulation dynamically influences activity in several regions of the frontal cortex and effectively improves cognition in schizophrenia. In this manuscript, we summarize current literature on the cingulocerebellar circuit and we introduce a method to interrogate this circuit combining opotogenetics, neuropharmacology, and electrophysiology in awake-behaving animals while minimizing incidental stimulation of neighboring cerebellar nuclei. We propose the novel hypothesis that optogenetic cerebellar stimulation can restore aberrant frontal activity and rescue impaired cognition in schizophrenia. We focus on how a known cognitive region in the frontal cortex, the anterior cingulate, is influenced by the cerebellum. This circuit is of particular interest because it has been confirmed using tracing studies, neuroimaging reveals its role in cognitive tasks, it is conserved from rodents to humans, and diseases such as schizophrenia and autism appear in its aberrancy. Novel tract tracing results presented here provide support for how these two areas communicate. The primary pathway involves a disynaptic connection between the cerebellar dentate nuclei (DN) and the anterior cingulate cortex. Secondarily, the pathway from cerebellar fastigial nuclei (FN) to the ventral tegmental area, which supplies dopamine to the prefrontal cortex, may play a role as schizophrenia characteristically involves dopamine deficiencies. We hope that the hypothesis described here will inspire new therapeutic strategies targeting currently untreatable cognitive impairments in schizophrenia.

Cerebellar Stroke-manifesting as Mania

Secondary mania resulting from cerebral Cortex are described commonly. But secondary mania produced by cerebellar lesions are relatively uncommon. This case report describes a patient who developed cerebellar stoke and manic features simultaneously. 28 years old male developed giddiness and projectile vomiting. Then he would lie down for about an hour only to find that he could not walk. He became quarrelsome. His Psycho motor activities and speech were increased. He was euphoric and was expressing grandiose ideas. Bender Gestalt Test showed signs of organicity. Score in Young mania relating scale was 32; productivity was low in Rorschach. Neurological examination revealed left cerebellar signs like ataxia and slurring of speech. Computed tomography of brain showed left cerebellar infarct. Relationship between Psychiatric manifestations and cerebellar lesion are discussed.

Converging genetic and functional brain imaging evidence links neuronal excitability to working memory, psychiatric disease, and brain activity

Working memory, the capacity of actively maintaining task-relevant information during a cognitive task, is a heritable trait. Working memory deficits are characteristic for many psychiatric disorders. We performed genome-wide gene set enrichment analyses in multiple independent data sets of young and aged cognitively healthy subjects (n = 2,824) and in a large schizophrenia case-control sample (n = 32,143). The voltage-gated cation channel activity gene set, consisting of genes related to neuronal excitability, was robustly linked to performance in working memory-related tasks across ages and to schizophrenia. Functional brain imaging in 707 healthy participants linked this gene set also to working memory-related activity in the parietal cortex and the cerebellum. Gene set analyses may help to dissect the molecular underpinnings of cognitive dimensions, brain activity, and psychopathology.

Consensus paper: the cerebellum's role in movement and cognition

While the cerebellum's role in motor function is well recognized, the nature of its concurrent role in cognitive function remains considerably less clear. The current consensus paper gathers diverse views on a variety of important roles played by the cerebellum across a range of cognitive and emotional functions. This paper considers the cerebellum in relation to neurocognitive development, language function, working memory, executive function, and the development of cerebellar internal control models and reflects upon some of the ways in which better understanding the cerebellum's status as a "supervised learning machine" can enrich our ability to understand human function and adaptation. As all contributors agree that the cerebellum plays a role in cognition, there is also an agreement that this conclusion remains highly inferential. Many conclusions about the role of the cerebellum in cognition originate from applying known information about cerebellar contributions to the coordination and quality of movement. These inferences are based on the uniformity of the cerebellum's compositional infrastructure and its apparent modular organization. There is considerable support for this view, based upon observations of patients with pathology within the cerebellum.

Plasma levels of 3-methoxy-4-hydroxyphenylglycol are associated with microstructural changes within the cerebellum in the early stage of first-episode schizophrenia: a longitudinal VBM study

The aims of this study are to determine how the interval changes of the brain structures in the early stage of first-episode schizophrenia relate to the interval changes in the clinical data, including the clinical symptoms of schizophrenia and catecholaminergic measures (plasma homovanillic acid [HVA] and 3-methoxy-4-hydroxyphenylglycol [MHPG]). Regional brain volumes and fractional anisotropy (FA)/mean diffusivity (MD) with diffusion tensor imaging (DTI) were measured at baseline and 6-month follow-up in a 3T magnetic resonance imaging (MRI) system in a cohort of 16 schizophrenic patients, who were in their first episode at the time of baseline MRI. At the time of baseline and follow-up MRI, all 16 patients underwent evaluations that included a psychopathological assessment (Positive and Negative Syndrome Scale [PANSS]) and peripheral catecholaminergic measures (plasma MHPG or HVA). For interval changes between baseline and follow-up MRI data (morphological change, MD, and FA), the correlation/regression analysis was performed as a series of single regression correlations in Statistical Parametric Mapping 5, with the interval changes in PANSS or plasma HVA and MHPG as the covariates of interest. Positive and inverse correlations contrasts were created, and in this preliminary analysis, a family-wise error-corrected threshold of P<0.05 was considered significant. In the correlation/regression analysis, a positive correlation between the FA in the right cerebellar vermis and the MHPG was observed. No significant correlations between the brain volume or MD and any laboratory data (plasma HVA and MHPG) were found. During the 6-month follow-up in the early stage of first-episode schizophrenia, the MHPG changes were correlated with the microstructural FA changes in the cerebellum, which may reflect the functional connections of the noradrenergic system in the cerebellum.

Eyeblink conditioning in unmedicated schizophrenia patients: a positron emission tomography study

Previous studies suggest that patients with schizophrenia exhibit dysfunctions in a widely distributed circuit-the cortico-cerebellar-thalamic-cortical circuit, or CCTCC-and that this may explain the multiple cognitive deficits observed in the disorder. This study uses positron emission tomography (PET) with O(15) H₂O to measure regional cerebral blood flow (rCBF) in response to a classic test of cerebellar function, the associative learning that occurs during eyeblink conditioning, in a sample of 20 unmedicated schizophrenia patients and 20 closely matched healthy controls. The PET paradigm examined three phases of acquisition and extinction (early, middle and late). The patients displayed impaired behavioral performance during both acquisition and extinction. The imaging data indicate that, compared to the control subjects, the patients displayed decreases in rCBF in all three components of the CCTCC during both acquisition and extinction. Specifically, patients had less rCBF in the middle and medial frontal lobes, anterior cerebellar lobules I/V and VI, as well as the thalamus during acquisition and although similar areas were found in the frontal lobe, ipsilateral cerebellar lobule IX showed consistently less activity in patients during extinction. Thus this study provides additional support for the hypothesis that patients with schizophrenia have a cognitive dysmetria--an inability to smoothly coordinate many different types of mental activity--that affects even a very basic cognitive task that taps into associative learning.

Stable signatures of schizophrenia in the cortical-subcortical-cerebellar network using fMRI of verbal working memory

A dysfunction in working memory (WM) is a core cognitive impairment in schizophrenia that involves the cortical-subcortical-cerebellar network. We propose that in addition to other often-referred markers, the signal reduction in the network during verbal working memory (VWM) is a stable and intrinsic indicator of illness. We presented a Sternberg VWM task to 46 patients with schizophrenia and 46 healthy controls matched on performance accuracy during functional magnetic resonance imaging (fMRI). Reduced activation was demonstrated in the thalamus, cerebellar vermis, pons and the triangular part of the inferior frontal gyrus (IFG) in the patient group. We also found a "failure of deactivation" in the default mode network (DMN) in patients as represented by a low versus high load VWM. In addition, a reduced left lateralization in the triangular and opercular parts of the IFG was observed in the patient group replicating previous "failure of lateralization" findings in schizophrenia. A comparison of long (10 to 19 years) and short (3 to 9 years) durations of illness (DoIs) demonstrated that the DoI was only associated with the activation changes in the middle frontal gyrus and lateral temporal cortex but not with the IFG-subcortico-cerebellar regions observed. These alterations were consistent with the cognitive dysmetria described in the cortical-subcortical-cerebellar network in schizophrenia. In conclusion, the combination of reduced activation in the cortical-subcortical-cerebellar network during VWM in particular, reduced deactivation in the DMN and reduced lateralization in the IFG is thought to be stable neuroimaging signatures of schizophrenia.

Resting-state fMRI mapping of cerebellar functional dysconnections involving multiple large-scale networks in patients with schizophrenia

BACKGROUND

Recent findings have indicated that patients with schizophrenia have altered cortico-cerebellar connectivity, but the nature of these network dysconnections remains unclear.

AIMS

We applied a network-based approach to investigate the functional connectivity (FC) of the cerebellum in patients with schizophrenia.

METHODS

Thirty-six patients with schizophrenia and 36 healthy controls underwent resting functional magnetic resonance imaging. We derived the following 6 major networks by applying group independent component analysis: (1) the cingulo-opercular network (CON); (2) the dorsal default-mode networks (dDMN); (3) the ventral default-mode network (vDMN); (4) the left frontoparietal networks (lFPN); (5) the right frontoparietal network (rFPN); and (6) the motor network (MOT). We defined 12 regions of interest (ROIs) by selecting the first 2 peaks of each network in the cerebellum. The FC map of all ROIs was calculated for each participant and compared between groups.

RESULTS

The schizophrenic patients showed a decrease in FC between the cerebellar ROIs and the thalamus in all networks except the MOT. The FC decreased between cerebellar ROIs and the frontal cortex in the CON, rFPN, and MOT. However, the FC increased with the precentral gyrus and postcentral gyrus for the CON, lFPN, and dDMN. An increased FC with the occipital fusiform gyrus and the temporal occipital fusiform gyrus was also noted in the dDMN, vDMN, and MOT.

CONCLUSIONS

The dysconnection of the cerebellum in the examined patients with schizophrenia was network-specific. The cerebellar-thalamic dysconnections were the most prominent findings and were common to all cognitive-related networks, whereas the cortico-cerebellar connectivity involved both an increase and decrease in FC, and depended more on the nature of the specific network.

Mechanisms of compartmental purkinje cell death and survival in the lurcher mutant mouse

The Lurcher mutant mouse is characterized by its ataxic gait and loss of cerebellar Purkinje cells and their afferents, granule cells and olivary neurons, during the first weeks of postnatal development. For the 50 years since its discovery, the heterozygous Lurcher mutant has served as an important model system for studying neuron-target interactions in the developing cerebellum and cerebellar function. The identification of the Lurcher (Lc) gene over 10 years ago as a gain-of-function mutation in the δ2 glutamate receptor (GluRδ2) led to extensive studies of cell death mechanisms in the Lc/+ cerebellum. The advantage of this model system is that GluRδ2(+) receptors and GluRδ2(Lc) channels are expressed predominantly in Purkinje cells, making it possible to study the effects of a well-characterized leak current in a well-defined cell type during a critical phase of neuronal development. Yet there is still controversy surrounding the mechanisms of neuronal death in Lc/+ Purkinje cells with competing hypotheses for necrotic, apoptotic, and autophagic cell death pathways as a consequence of the excitotoxic stress caused by the GluRδ2(Lc) leak current. The goal of this review is to summarize recent studies that critically test the role of various cell death pathways in Lc/+ Purkinje cell degeneration with respect to evidence for the molecular heterogeneity of Purkinje cells. We propose that the expression of putative survival factors, such as heat shock proteins, in a subset of cerebellar Purkinje cells may affect cell death pathways and account for the pattern and diverse mechanisms of Lc/+ Purkinje degeneration.

Psychosis and Dandy-Walker complex: report of four cases

Concurrence of psychosis and Dandy-Walker complex (DWC) has been reported in some medical literature. Here, we reported four patients with concurrent psychosis and DWC of all four subtypes. Some clinical features found were juvenile or young adult age onset, high frequency of family history of psychosis, atypical psychotic symptoms, and high prevalence of cognitive deficit and refractoriness to treatment, in line with the cases in previous reports. These findings might help further illuminate the role that the cerebellum plays in the etiology of schizophrenia or bipolar disorder.

White matter alterations related to P300 abnormalities in individuals at high risk for psychosis: an MRI-EEG study

BACKGROUND

Psychosis onset is characterized by white matter and electrophysiologic abnormalities. The relation between these factors in the development of illness is almost unknown. We studied the relation between white matter volumes and P300 in prodromal psychosis.

METHODS

We assessed white matter volume (detected using magnetic resonance imaging) and electrophysiologic response during an oddball task (P300) in healthy controls and individuals at high clinical risk for psychosis (with an "at-risk mental state" [ARMS]).

RESULTS

We included 41 controls and 39 patients with an ARMS in our study. A psychotic disorder developed in 26% of the ARMS group within the follow-up period of 2 years. The P300 amplitude was significantly lower in the ARMS group than in the control group. The ARMS group showed reduced volume of white matter underlying the left superior temporal gyrus and the left superior frontal gyrus and increased volume of white matter underlying the right insula and the right angular gyrus compared with controls. Relative to individuals who did not later become psychotic, the subgroup in whom psychosis subsequently developed had a smaller volume of white matter underlying the left precuneus and the right middle temporal gyrus and increased volume in the white matter underlying the right middle frontal gyrus. We observed a significant interaction in the right middle frontal gyrus: white matter volume was negatively associated with P300 amplitude in the ARMS group and positively associated with P300 amplitude in the control group.

LIMITATIONS

The voxel-based morphometry method alone cannot determine whether abnormal white matter volumes are due to an altered number of axonal connections or decreased myelination.

CONCLUSION

P300 abnormalities precede the onset of psychosis and are directly related to white matter alterations, representing a correlate of an increased vulnerability to disease.

Parietal cortex and episodic memory retrieval in schizophrenia

People with schizophrenia consistently show memory impairment on varying tasks including item recognition memory. Relative to the correct rejection of distracter items, the correct recognition of studied items consistently produces an effect termed the old/new effect that is characterized by increased activity in parietal and frontal cortical regions. This effect has received only scant attention in schizophrenia. We examined the old/new effect in 15 people with schizophrenia and 18 controls during an item recognition test, and neural activity was examined with event-related functional magnetic resonance imaging. Both groups performed equally well during the recognition test and showed increased activity in a left dorsolateral prefrontal region and in the precuneus bilaterally during the successful recognition of old items relative to the correct rejection of new items. The control group also exhibited increased activity in the dorsal left parietal cortex. This region has been implicated in the top-down modulation of memory which involves control processes that support memory-retrieval search, monitoring and verification. Although these processes may not be of paramount importance in item recognition memory performance, the present findings suggest that people with schizophrenia may have difficulty with such top-down modulation, a finding consistent with many other studies in information processing.

MR diffusion tensor imaging: a window into white matter integrity of the working brain

As Norman Geschwind asserted in 1965, syndromes resulting from white matter lesions could produce deficits in higher-order functions and "disconnexion" or the interruption of connection between gray matter regions could be as disruptive as trauma to those regions per se. The advent of in vivo diffusion tensor imaging, which allows quantitative characterization of white matter fiber integrity in health and disease, has served to strengthen Geschwind's proposal. Here we present an overview of the principles of diffusion tensor imaging (DTI) and its contribution to progress in our current understanding of normal and pathological brain function.

Recruitment of additional brain regions to accomplish simple motor tasks in chronic alcohol-dependent patients

BACKGROUND

Chronic alcohol-dependent patients (ALC) exhibit neurocognitive impairments attributed to alcohol-induced fronto-cerebellar damage. Deficits are typically found in complex task performance, whereas simple tasks may not be significantly compromised, perhaps because of little understood compensatory changes.

METHODS

We compared finger tapping with either hand at externally paced (EP) or maximal self-paced (SP) rates and concomitant brain activation in ten pairs of right-hand dominant, age-, and gender-matched, severe, uncomplicated ALC and normal controls (NC) using functional magnetic resonance imaging (fMRI).

RESULTS

Mean tapping rates were not significantly different in ALC and NC for either task, but SP tapping variances were greater in ALC for both hands. SP tapping was more rapid with dominant hand (DH) than non-dominant hand (NDH) for both groups. EP and SP tapping with the non-dominant hand demonstrated significantly more activation in ALC than NC in the pre and postcentral gyri, inferior frontal gyrus, inferior parietal lobule, and the middle temporal gyrus. Areas activated only by ALC (not at all by NC) during NDH tapping included the inferior frontal gyrus, middle temporal gyrus, and postcentral gyrus. There were no significant group activation differences with DH tapping. No brain regions activated more in NC than ALC. SP tapping in contrast to EP activated fronto-cerebellar networks in NC, including postcentral gyrus, anterior cingulate, and the anterior lobe and vermis of the cerebellum, but only parietal precuneus in ALC.

CONCLUSIONS

These findings with NDH finger tapping support previous reports of neurocognitive inefficiencies in ALC. Inferior frontal activation with EP in ALC, but not in NC, suggests engagement of regions needed for planning, organization, and impulse regulation; greater contralateral parietal lobe activation with SP in ALC may reflect right hemispheric impairments in visuospatial performance. Contrasting brain activation during SP and EP suggests that ALC may not have enlisted a fronto-cerebellar network as did NC but rather employed a higher order planning mode by recruiting parietal lobe functions to attain normal mean finger tapping rates. Elucidation of the compensatory neural mechanisms that allow near normal performance by ALC on simple tasks can inform functional rehabilitation of patients in recovery.

Fluctuation of gamma-band phase synchronization within the auditory cortex in schizophrenia

OBJECTIVE

To study the phase stability of the 40Hz auditory steady-state response (ASSR) in Sz, and in addition, to investigate inter-hemispheric phase synchronization using ipsilateral and contralateral hemisphere gamma band ASSRs.

METHODS

Whole head magnetoencephalography (MEG) was used to detect ASSR from both hemispheres in Sz patients and their control counterparts. Source localization, spatial and temporal filtering were performed to infer gamma band activity from the neural generators of the ASSR. The response gamma band phase stability relative to a reference signal was quantified using the phase synchronization index (PSI).

RESULTS

Results indicated reduced phase synchronization of the ASSR and the stimulus reference signal in Sz patients compared to control subjects, in addition to reduced inter-hemispheric phase synchronization between contralateral and ipsilateral hemispheric responses in Sz patients.

CONCLUSIONS

Greater intra and inter hemispheric fluctuations of ASSR gamma band phase synchronization in Sz add to previous studies suggesting timing deficiencies within neural populations, possibly caused by impairments of neural network parameters.

SIGNIFICANCE

This study provides experimental support that may aid in understanding the dynamics of neural phase synchrony caused by modifications of underlying neurotransmitter systems, as reflected in disease states such as schizophrenia.

Prefrontal activation deficits during episodic memory in schizophrenia

OBJECTIVE

Episodic memory impairments represent a core deficit in schizophrenia that severely limits patients' functional outcome. This quantitative meta-analysis of functional imaging studies of episodic encoding and retrieval tests the prediction that these deficits are most consistently associated with dysfunction in the prefrontal cortex.

METHOD

Activation likelihood estimation (ALE) was used to perform a quantitative meta-analysis of functional imaging studies that contrasted patients with schizophrenia and healthy volunteers during episodic encoding and retrieval. From a pool of 36 potential studies, 18 whole-brain studies in standard space that included a healthy comparison sample and low-level baseline contrast were selected.

RESULTS

As predicted, patients showed less prefrontal activation than comparison subjects in the frontal pole, dorsolateral and ventrolateral prefrontal cortex during encoding, and the dorsolateral prefrontal cortex and ventrolateral prefrontal cortex during retrieval. The ventrolateral prefrontal cortex encoding deficits were not present in studies that provided patients with encoding strategies, but dorsolateral prefrontal cortex deficits remained and were not secondary to group performance differences. The only medial temporal lobe finding was relatively greater patient versus comparison subject activation in the parahippocampal gyrus during encoding and retrieval.

CONCLUSIONS

The finding of prominent prefrontal dysfunction suggests that cognitive control deficits strongly contribute to episodic memory impairment in schizophrenia. Memory rehabilitation approaches developed for patients with frontal lobe lesions and pharmacotherapy approaches designed to improve prefrontal cortex function may therefore hold special promise for remediating memory deficits in patients with schizophrenia.

The role of the cerebellum in the pathophysiology and treatment of neuropsychiatric disorders: a review

The cerebellum has traditionally been looked upon as a brain area primarily involved in motor behaviour. The last decade has however heralded the cerebellum as a brain region of renewed interest for neuropsychiatric disorders. This renewed interest is fuelled by new insights obtained from neuroanatomical research, modern functional neuroimaging and transcranial magnetic stimulation studies. In this review, evidence in support of cerebellar involvement in neuropsychiatric disorders will be presented. In addition, transcranial magnetic stimulation will be introduced as a novel way to study cerebellar contributions to the pathophysiology of psychiatric disorders. In conclusion, a new functional concept of the cerebellum as more than simply a brain area regulating motor control appears mandatory and the involvement of the cerebellum should be considered when studying the neurological basis of neuropsychiatric disorders.

Cerebral differences in explicit and implicit emotional processing--an fMRI study

The processing of emotional facial expression is a major part of social communication and understanding. In addition to explicit processing, facial expressions are also processed rapidly and automatically in the absence of explicit awareness. We investigated 12 healthy subjects by presenting them with an implicit and explicit emotional paradigm. The subjects reacted significantly faster in implicit than in explicit trials but did not differ in their error ratio. For the implicit condition increased signals were observed in particular in the thalami, the hippocampi, the frontal inferior gyri and the right middle temporal region. The analysis of the explicit condition showed increased blood-oxygen-level-dependent signals especially in the caudate nucleus, the cingulum and the right prefrontal cortex. The direct comparison of these 2 different processes revealed increased activity for explicit trials in the inferior, superior and middle frontal gyri, the middle cingulum and left parietal regions. Additional signal increases were detected in occipital regions, the cerebellum, and the right angular and lingual gyrus. Our data partially confirm the hypothesis of different neural substrates for the processing of implicit and explicit emotional stimuli.

Quantitative analysis of ataxic gait in patients with schizophrenia: the influence of age and visual control

Previous research has determined that patients with schizophrenia classically exhibit ataxic gait. Age and visual controls of balance are important factors, and may influence gait, but have not been controlled. A total of 100 patients with schizophrenia were included in this study, along with 50 age- and sex-matched healthy controls. They were sampled with methods which stratified both groups according to age and sex. Tandem gait tests were conducted with eyes open and closed, and gait parameters were assessed by the footprint method. Ataxic gait was found to be significantly more frequent in the schizophrenic group. With eyes open, ataxic gait showed a significant increase with age in the schizophrenic group, but not in the healthy control group. Adjusting ataxic gait of the patients on the basis of the normal age effects measured in the healthy control group, the ataxic gait in the schizophrenic group increased according to age. Multiple logistic regression analysis revealed that old age and previous history of alcohol dependence/abuse were the risk factors for ataxic gait with eyes open. This implies that a dysfunction of the visuo-cerebellar circuit in patients with schizophrenia increases according to age.

The cerebellum and emotional experience

While the role of the cerebellum in motor coordination is widely accepted, the notion that it is involved in emotion has only recently gained popularity. To date, functional neuroimaging has not been used in combination with lesion studies to elucidate the role of the cerebellum in the processing of emotional material. We examined six participants with cerebellar stroke and nine age and education matched healthy volunteers. In addition to a complete neuropsychological, neurologic, and psychiatric examination, participants underwent [15O]water positron emission tomography (PET) while responding to emotion-evoking visual stimuli. Cerebellar lesions were associated with reduced pleasant experience in response to happiness-evoking stimuli. Stroke patients reported an unpleasant experience to frightening stimuli similar to healthy controls, yet showed significantly lower activity in the right ventral lateral and left dorsolateral prefrontal cortex, amygdala, thalamus, and retrosplenial cingulate gyrus. Frightening stimuli led to increased activity in the ventral medial prefrontal, anterior cingulate, pulvinar, and insular cortex. This suggests that alternate neural circuitry became responsible for maintaining the evolutionarily critical fear response after cerebellar damage.

Fronto-cerebellar systems are associated with infant motor and adult executive functions in healthy adults but not in schizophrenia

Delineating longitudinal relationships between early developmental markers, adult cognitive function, and adult brain structure could clarify the pathogenesis of neurodevelopmental disorders such as schizophrenia. We aimed to identify brain structural correlates of infant motor development (IMD) and adult executive function in nonpsychotic adults and to test for abnormal associations between these measures in people with schizophrenia. Representative samples of nonpsychotic adults (n = 93) and people with schizophrenia (n = 49) were drawn from the Northern Finland 1966 general population birth cohort. IMD was prospectively assessed at age 1 year; executive function testing and MRI were completed at age 33-35 years. We found that earlier motor development in infancy was correlated with superior executive function in nonpsychotic subjects. Earlier motor development was also normally associated with increased gray matter density in adult premotor cortex, striatum, and cerebellum and increased white matter density in frontal and parietal lobes. Adult executive function was normally associated with increased gray matter density in a fronto-cerebellar system that partially overlapped, but was not identical to, the gray matter regions normally associated with IMD. People with schizophrenia had relatively delayed IMD and impaired adult executive function in adulthood. Furthermore, they demonstrated no normative associations between fronto-cerebellar structure, IMD, or executive function. We conclude that frontal cortico-cerebellar systems correlated with adult executive function are anatomically related to systems associated with normal infant motor development. Disruption of this anatomical system may underlie both the early developmental and adult cognitive abnormalities in schizophrenia.

Differential effects of haloperidol and olanzapine on levels of vascular endothelial growth factor and angiogenesis in rat hippocampus

Compared to first-generation antipsychotics (FGAs) such as haloperidol, second-generation antipsychotics (SGAs) such as olanzapine are found superior to improve cognitive performance and reduce negative symptoms with no extrapyramidal symptoms (EPS). These clinical effects of SGAs have been reported to be associated with the most replicated phenomenon, favorable changes in brain regional blood flow and volume. The changes in brain regional blood flow are shown to parallel changes in angiogenesis, which is primarily mediated by vascular endothelial growth factor (VEGF) through its receptor, Flk-1, on endothelial cells. Therefore, we studied the differential effects of time-dependent treatment (14 and 45 days) with haloperidol and olanzapine (2 and 10 mg/kg/day, respectively, in drinking water) on hippocampal levels of VEGF, its receptor Flk-1, and angiogenesis in adult rat. The levels of VEGF were determined by both Western blot analysis and ELISA, and Flk-1 levels were determined by Western blot analysis. Immunohistochemical analysis of rat endothelial cell antigen-1 (RECA-1) and laminin were used to evaluate the changes in angiogenesis. After 14 days of treatment with both haloperidol and olanzapine, the levels of VEGF and angiogenesis were significantly increased (p<0.001 vs vehicle for both), but 45 days of treatment with haloperidol reduced their levels back to levels in vehicle-treated rats. However, olanzapine treatment further increased VEGF levels (p<0.05 vs levels after 14 days of treatment). Changes in the levels of Flk-1 paralleled the changes in VEGF levels. Thus, the data indicate that haloperidol and olanzapine have distinct time-dependent patterns of regulation of VEGF and angiogenesis. These changes probably provide a new molecular mechanism to better explain their differential effects on the patterns of regional blood flow and associated changes in regional volume/neuroplasticity and psychopathology.

Quantitative analysis of motor disturbances in schizophrenic patients

The presence of neurological signs and disturbed psychomotor performance have been consistently confirmed by clinical studies in schizophrenic patients. These parameters are mainly assessed by using clinical rating scales. In recent years, new approaches such as ultrasonic movement analysis systems have been introduced in order to objectively evaluate motor disturbances in schizophrenic patients. Ultrasonic movement analysis systems calculate the three-dimensional positions of tiny markers, which are attached to moving body parts, with high spatial and temporal resolution. Thus, key parameters of gait and hand movements can be determined precisely. This article summarizes and discusses several studies using these new methods. Results indicate that schizophrenia causes a specific motor deficit pattern, with a predominant disturbance of spatial parameters. Conventional antipsychotic treatment usually worsens these deficits, whereas the effects of atypical antipsychotic treatments are less pronounced. Disturbed motor performance can be normalized by external sensory stimuli, but only when no major attentional processes are required, and it can be enhanced by an attentional strategy, but not to the extent that motor parameters are normalized.

Neural activation during successful and unsuccessful verbal learning in schizophrenia

Successful and unsuccessful intention to learn words was assessed by means of event-related functional MRI. Eighteen patients with schizophrenia and 15 healthy control participants were scanned while being given two word lists to read and another seven to learn with immediate recall. Neural activation patterns were segregated according to whether words were subsequently recalled or forgotten and these conditions were contrasted with each other and reading. Compared to controls, patients with schizophrenia showed deficits with regard to neural recruitment of right hippocampus and of cerebellar structures during successful verbal learning. Furthermore, a reversal of activated structures was evident in the two groups: Controls showed activation of right frontal and left middle temporal structures during the unsuccessful intention to learn. During successful learning, there was additional activation of right superior parietal lobule. In contrast, patients showed activation of right superior parietal lobule during unsuccessful and successful intention to learn. There were additional frontal and left middle temporal lobe activations during successful learning. We conclude that increased parietal activity may reflect a mechanism which compensates for the lack of hippocampal and cerebellar contributions to verbal learning in schizophrenia.

Prism adaptation in schizophrenia

The prism adaptation test examines procedural learning (PL) in which performance facilitation occurs with practice on tasks without the need for conscious awareness. Dynamic interactions between frontostriatal cortices, basal ganglia, and the cerebellum have been shown to play key roles in PL. Disruptions within these neural networks have also been implicated in schizophrenia, and such disruptions may manifest as impairment in prism adaptation test performance in schizophrenia patients. This study examined prism adaptation in a sample of patients diagnosed with schizophrenia (N=91) and healthy normal controls (N=58). Quantitative indices of performance during prism adaptation conditions with and without visual feedback were studied. Schizophrenia patients were significantly more impaired in adapting to prism distortion and demonstrated poorer quality of PL. Patients did not differ from healthy controls on aftereffects when the prisms were removed, but they had significantly greater difficulties in reorientation. Deficits in prism adaptation among schizophrenia patients may be due to abnormalities in motor programming arising from the disruptions within the neural networks that subserve PL.

Episodic memory-related activation in schizophrenia: meta-analysis

BACKGROUND

Numerous studies have examined the neural correlates of episodic memory deficits in schizophrenia, yielding both consistencies and discrepancies in the reported patterns of results.

AIMS

To identify in schizophrenia the brain regions in which activity is consistently abnormal across imaging studies of memory.

METHOD

Data from 18 studies meeting the inclusion criteria were combined using a recently developed quantitative meta-analytic approach.

RESULTS

Regions of consistent differential activation between groups were observed in the left inferior prefrontal cortex, medial temporal cortex bilaterally, left cerebellum, and in other prefrontal and temporal lobe regions. Subsequent analyses explored memory encoding and retrieval separately and identified between-group differences in specific prefrontal and medial temporal lobe regions.

CONCLUSIONS

Beneath the apparent heterogeneity of published findings on schizophrenia and memory, a consistent and robust pattern of group differences is observed as a function of memory processes.

Functional dysconnectivity in schizophrenia associated with attentional modulation of motor function

It is not known whether there is a core abnormality that occurs in all cases of schizophrenia. The cognitive dysmetria hypothesis proposes that there is such an abnormality which is characterized cognitively by a disruption in control and coordination processes, and functionally by abnormal inter-regional connectivity within the cortico-cerebellar-thalamo-cortical circuit (CCTCC). In the current study, we used functional MRI (fMRI) to investigate these two key aspects of the hypothesis. Since patients with schizophrenia show deficits in attention which have been characterized extensively using the continuous performance task (CPT) and since functional imaging studies have also demonstrated that this task engages the CCTCC, we used this task to investigate whether two patient groups with distinct symptom profiles would show functional dysconnectivity within this network. Three groups of subjects participated in the study: healthy volunteers (n = 12), schizophrenia patients with both negative and positive symptoms (n = 11) and schizophrenia patients with primarily positive symptoms (n = 11). Patient groups were matched for age of illness onset and medication, and to the control group for age, gender and handedness. Subjects were scanned using fMRI whilst they performed a modified version of the CPT, involving both degraded and non-degraded stimuli. Stimulus degradation has been shown to produce decrements in sensitivity, which is thought to reflect increased demands on the limited capacity of visual attention. Between-group comparisons revealed that patients with schizophrenia, irrespective of symptomatology, showed attenuation of the anterior cingulate and cerebellar response to stimulus degradation in comparison with control subjects. We also observed disruptions of inter-regional brain integration in schizophrenia. A task-specific relationship between the medial superior frontal gyrus and both anterior cingulate and the cerebellum was disrupted in both patient groups in comparison with controls. In addition, patients with negative symptoms showed impaired behavioural performance, and abnormal task-related connectivity between anterior cingulate and supplementary motor area. These findings are consistent with theoretical accounts of schizophrenia as a disorder of functional integration, and with the cognitive dysmetria hypothesis, which posits a disconnection within the CCTCC as a fundamental abnormality in schizophrenia, independent of diagnostic subtype. Furthermore, these data show evidence of additional functional deficits in patients with negative symptoms, deficits which may explain the accompanying attentional impairment.

Prefrontal cognitive functions in stabilized first-episode patients with schizophrenia spectrum disorders: a dissociation between dorsolateral and orbitofrontal functioning

Specific prefrontal cognitive impairments have been reported in first-episode and chronic schizophrenia. We sought to investigate potential impairments in specific prefrontal cortical cognitive functions among stabilized patients with a first-episode of schizophrenia. A sample of 80 individuals with a first-episode of schizophrenia spectrum disorders and 22 healthy volunteers underwent a neurocognitive battery assessing orbitofrontal (OFC) [The Iowa Gambling Task (GT)], and dorsolateral prefrontal (DLPFC) functions (WAIS III Backward digits, verbal fluency test (FAS), and Trail Making Test). Cognitive data were obtained following stabilization of acute psychotic symptoms. Clinical symptoms after six weeks of treatment were assessed by using the SAPS and SANS scales. While there were no significant group differences in overall scores and in the profile of progress of performance along periods on the GT, patient group showed a significant impairment when performing DLPFC tasks. Only FAS score was correlated to the severity of negative symptomatology. The OFC functions are unimpaired at the early phases of psychosis and in contrast there is a significant deficit in DLPFC functions in first-episode of schizophrenia.