Brain Regions In Schizophrenia Research Articles

Aberrant connectivity during self–other source monitoring in schizophrenia

Numerous investigations into schizophrenia have reported impairment in self–other source monitoring, and studies on healthy subjects have suggested that the medial prefrontal cortex (mPFC) is a critical region underlying self-monitoring abilities. In the current study, we examined the mPFC-related modulation of other brain regions in schizophrenia during self–other monitoring using a psychophysiological interaction approach. Twenty-three patients with schizophrenia and 33 healthy controls performed a self–other source monitoring task while undergoing functional magnetic resonance imaging (fMRI) scanning. Independent component analysis was used to identify the mPFC region of interest, and the averaged mPFC time course was extracted and entered into a general linear regression model for use with the psychophysiological interaction analysis, with Self vs. Other monitoring being the psychological condition of interest. Results suggested that connectivity between the mPFC and the left superior temporal gyrus (LSTG) was greater in the Other than the Self condition for the healthy subjects, but this was reversed for the schizophrenia patients, such that mPFC-LSTG connectivity was greater during Self than the Other condition. The modified functional connectivity associated with the performance of recollection of self-source information suggests that schizophrenia patients invoke circuits normally involved in retrieving other-generated information when processing self-generated information, thereby providing a possible biological basis for the self–other confusion characteristic of schizophrenia.

Gene expression abnormalities and oligodendrocyte deficits in the internal capsule in schizophrenia

Deficits in the expression of oligodendrocyte (Ol) and myelin genes have been described in numerous brain regions in schizophrenia (SZ) in association with abnormalities of cell cycle markers. We have previously reported a SZ-associated decrease in the expression of genes expressed after, but not prior to, the terminal differentiation of Ols in the posterior limb of the internal capsule (ICp). This pattern of deficits could reflect a failure of Ol precursors to exit the cell cycle and differentiate to meet the demands imposed by the high rate of apoptosis among myelinating Ols. Here we explore this hypothesis using quantitative real time PCR to examine the mRNA expression of additional genes in the ICp of the previously examined sample of 14 subjects with SZ and 15 normal controls (NCs). The genes examined in the present study were chosen because they are associated with particular phases of the cell cycle (CCND1, CCND2, p21Cip1, p27Kip1, and p57Kip2), with DNA replication and repair (PCNA), apoptosis (CASP3), or the Notch signaling pathway (JAG1, HES1, HES5, andDTX1). The Notch pathway influences whether Ol precursors continue to proliferate or exit the cell cycle. We also determined the densities of Ols in the ICp. Genes associated with maintenance of the cell cycle tended to exhibit increased expression levels in SZ relative to NCs and to be negatively correlated with the expression levels of the previously assessed mature Ol genes. In contrast, genes associated with cell cycle arrest tended to show the opposite pattern (decreased expression in SZ and positive correlations with mature Ol genes). CASP3 and PCNA expression levels were significantly decreased in SZ and positively correlated with mature Ol genes, suggesting that myelinating Ols may turnover more rapidly in normal controls than in subjects with SZ. JAG1 expression was significantly increased in SZ and exhibited positive correlations with mediators of the canonical Notch pathway but negative correlations with mature Ol genes. Ol densities were significantly decreased in SZ. These data are consistent with the hypothesis that Ol and myelin deficits in SZ involve a failure of Ol precursors to appropriately exit the cell cycle in order to differentiate and mature into myelinating Ols.

Evidence for structural abnormalities of the human habenular complex in affective disorders but not in schizophrenia

The habenular complex is composed of important relay nuclei linking the limbic forebrain to the midbrain and brain stem nuclei. Based on clinical observations, experiments with animals and theoretical considerations, it has been speculated that this brain area might be involved in psychiatric diseases (i.e. schizophrenia and depression). However, evidence in favour of this hypothesis is still lacking because the human habenular complex has rarely been studied with regard to mental illness. We examined habenular volumes in post-mortem brains of 17 schizophrenia patients, 14 patients with depression (six patients with major depression and eight patients with bipolar depression) and 13 matched controls. We further determined the neuronal density, cell number and cell area of the medial habenular nuclei of the same cohorts using a counting box and a computer-assisted instrument. Significantly reduced habenular volumes of the medial and lateral habenula were estimated in depressive patients in comparison to normal controls and schizophrenia patients. We also found a reduction in neuronal cell number and cell area in depressive patients for the right side compared to controls and schizophrenia patients. No such changes were seen in schizophrenia. Our anatomical data argue against prominent structural alterations of the habenular nuclei in schizophrenia but demonstrate robust alterations in depressive patients. We are currently applying immunohistochemical markers to better characterize neuronal subpopulations of this brain region in schizophrenia and depression.

Gray Matter Deficits, Mismatch Negativity, and Outcomes in Schizophrenia

Reduced mismatch negativity (MMN) in response to auditory change is a well-established finding in schizophrenia and has been shown to be correlated with impaired daily functioning, rather than with hallmark signs and symptoms of the disorder. In this study, we investigated (1) whether the relationship between reduced MMN and impaired daily functioning is mediated by cortical volume loss in temporal and frontal brain regions in schizophrenia and (2) whether this relationship varies with the type of auditory deviant generating MMN. MMN in response to duration, frequency, and intensity deviants was recorded from 18 schizophrenia subjects and 18 pairwise age- and gender-matched healthy subjects. Patients' levels of global functioning were rated on the Social and Occupational Functioning Assessment Scale. High-resolution structural magnetic resonance scans were acquired to generate average cerebral cortex and temporal lobe models using cortical pattern matching. This technique allows accurate statistical comparison and averaging of cortical measures across subjects, despite wide variations in gyral patterns. MMN amplitude was reduced in schizophrenia patients and correlated with their impaired day-to-day function level. Only in patients, bilateral gray matter reduction in Heschl's gyrus, as well as motor and executive regions of the frontal cortex, correlated with reduced MMN amplitude in response to frequency deviants, while reduced gray matter in right Heschl's gyrus also correlated with reduced MMN to duration deviants. Our findings further support the importance of MMN reduction in schizophrenia by linking frontotemporal cerebral gray matter pathology to an automatically generated event-related potential index of daily functioning.

Differential Expression of Metabotropic Glutamate Receptors 2 and 3 in Schizophrenia: A Mechanism for Antipsychotic Drug Action?

Preclinical and clinical data implicate the group II metabotropic glutamate receptors mGluR2 and mGluR3 in the pathophysiology of schizophrenia. Moreover, a recent phase II clinical trial demonstrated the antipsychotic efficacy of a mGluR2/mGluR3 agonist. The purpose of the present study was to distinguish the expression of mGluR2 and mGluR3 receptor proteins in schizophrenia and to quantify glutamate carboxypeptidase II (GCP II) in order to explore a role for the metabotropic receptors in schizophrenia therapeutics. GCP II is an enzyme that metabolizes N-acetyl-aspartyl-glutamate (NAAG), which is the only known specific endogenous agonist of mGluR3 in the mammalian brain. The normal expression levels of mGluR2, mGluR3, and GCP II were determined for 10 regions of the postmortem human brain using specific antibodies. Differences in expression levels of each protein were examined in the dorsolateral prefrontal cortex, temporal cortex, and motor cortex in 15 postmortem schizophrenia subjects and 15 postmortem matched normal comparison subjects. Chronic antipsychotic treatment in rodents was conducted to examine the potential effect of antipsychotic drugs on expression of the three proteins. Findings revealed a significant increase in GCP II protein and a reduction in mGluR3 protein in the dorsolateral prefrontal cortex in schizophrenia subjects, with mGluR2 protein levels unchanged. Chronic antipsychotic treatment in rodents did not influence GCP II or mGluR3 levels. Increased GCP II expression and low mGluR3 expression in the dorsolateral prefrontal cortex suggest that NAAG-mediated signaling is impaired in this brain region in schizophrenia. Further, these data implicate the mGluR3 receptor in the antipsychotic action of mGluR2/mGluR3 agonists.

Microvessel length density, total length, and length per neuron in five subcortical regions in schizophrenia

Recent studies (Prabakaran et al. in Mol Psychiat 9:684-697, 2004; Hanson and Gottesman in BMC Med Genet 6:7, 2005; Harris et al. in PLoS ONE 3:e3964, 2008) have suggested that microvascular abnormalities occur in the brains of patients with schizophrenia. To assess the integrity of the microvasculature in subcortical brain regions in schizophrenia, we investigated the microvessel length density, total microvessel length, and microvessel length per neuron using design-based stereologic methods in the caudate nucleus, putamen, nucleus accumbens, mediodorsal nucleus of the thalamus, and lateral nucleus of the amygdala in both hemispheres of 13 postmortem brains from male patients with schizophrenia and 13 age-matched male controls. A general linear model multivariate analysis of variance with diagnosis and hemisphere as fixed factors and illness duration (patients with schizophrenia) or age (controls), postmortem interval and fixation time as covariates showed no statistically significant differences in the brains from the patients with schizophrenia compared to the controls. These data extend our earlier findings in prefrontal cortex area 9 and anterior cingulate cortex area 24 from the same brains (Kreczmanski et al. in Acta Neuropathol 109:510-518, 2005), that alterations in microvessel length density, total length, and particularly length per neuron cannot be considered characteristic features of schizophrenia. As such, compromised brain metabolism and occurrence of oxidative stress in the brains of patients with schizophrenia are likely caused by other mechanisms such as functional disruption in the coupling of cerebral blood flow to neuronal metabolic needs.

Functional serotonin 1A receptor variant influences treatment response to atypical antipsychotics in schizophrenia

The serotonin (5-HT) 1A receptor has been found to be dysregulated in prefrontal cortex and other brain regions in schizophrenia, and 5-HT1A receptor levels in the amygdala have been related to negative schizophrenia symptoms. We have assessed the impact of the functional C-1019G variant of the 5-HT1A receptor on the response to risperidone or haloperidol in a prospective, randomized, double-blind study. Patients were treated for 4 weeks and negative symptoms assessed weekly. The variant influenced the response to risperidone: improvement of negative symptoms by 4.38 points for carriers of the C allele, compared with the GG genotype (1.22 points, P=0.046). In a second independent study of 130 schizophrenia patients treated with atypical antipsychotics, this effect was confirmed (P=0.003). The functional variant of the 5-HT1A receptor thus influences the response of schizophrenia patients to atypical antipsychotics and may be useful in the future to predict the pharmacogenetics of negative symptoms.

Proteomic analysis reveals protein changes within layer 2 of the insular cortex in schizophrenia

Abnormalities in the size and activity of the insular cortex (IC), a brain region involved in auditory hallucinations and language, have been previously found in brain imaging studies in schizophrenia. In addition, cortical layer 2 has been shown to be abnormal in many brain regions in schizophrenia. In this study, 2-D DIGE was used to quantitatively analyse protein expression in schizophrenia and control cases (n = 15/group) in microdissected layer 2 IC tissue. Proteomic analyses revealed 57 significantly differentially expressed (p<0.05) protein spots in schizophrenia. Validation of differential expression of two of the proteins differentially expressed was subsequently confirmed using Western blotting. This work provides evidence of abnormal protein expression in layer 2 of the IC in schizophrenia, supporting previous work of reduced neuronal size in this cortical layer in the IC. Over half of proteins abnormally expressed in this study have not been reported previously in proteomic studies investigating schizophrenia or neurodegenerative disorders. Proteins found to be abnormally expressed appear to collectively impact on neuronal plasticity through roles in neurite outgrowth, cellular morphogenesis and synaptic function.

31P NMR spectroscopy of phospholipid metabolites in postmortem schizophrenic brain

Evidence has been accumulating that schizophrenia involves abnormalities in the composition and metabolism of cell membrane phospholipids (PLs) in the brain. In vivo 31P MRS has been used to measure the metabolic precursors and degradation products of PL metabolism in schizophrenia. Because in vivo line widths are substantially broader than in solution, only the broad phosphomonoester (PME) and phosphodiester bands, or partly resolved resonances of individual metabolites, are typically measured in vivo in the 31P spectrum. In addition to poor resolution, the relatively low signal-to-noise ratio (SNR) makes precise quantitation difficult. An alternative with substantially better resolution and precision for quantitation is high-resolution NMR spectroscopy of extracts of samples from postmortem brain. Here we determine absolute concentrations of the individual PL metabolites phosphocholine (pc), phosphoethanolamine (pe), glycerophosphocholine (gpc), and glycerophosphoethanolamine in aqueous extracts of tissue from frontal, temporal, and occipital cortex of postmortem brain for schizophrenics, controls, and patients with other mental illnesses (psychiatric controls [PC]) using high-resolution 31P NMR spectroscopy. For the complete groups, which included both males and females, there were no statistically significant differences for schizophrenics vs. controls for any of the four PL metabolites in any of the three brain regions. Trends (0.05 < P < 0.10) were noted for increased gpc in schizophrenia in all three regions. PC differed from both controls and schizophrenics in several measures. When only males were considered, gpc was significantly (P < 0.05) elevated in all three brain regions in schizophrenia.

Disrupted small-world networks in schizophrenia

The human brain has been described as a large, sparse, complex network characterized by efficient small-world properties, which assure that the brain generates and integrates information with high efficiency. Many previous neuroimaging studies have provided consistent evidence of 'dysfunctional connectivity' among the brain regions in schizophrenia; however, little is known about whether or not this dysfunctional connectivity causes disruption of the topological properties of brain functional networks. To this end, we investigated the topological properties of human brain functional networks derived from resting-state functional magnetic resonance imaging (fMRI). Data was obtained from 31 schizophrenia patients and 31 healthy subjects; then functional connectivity between 90 cortical and sub-cortical regions was estimated by partial correlation analysis and thresholded to construct a set of undirected graphs. Our findings demonstrated that the brain functional networks had efficient small-world properties in the healthy subjects; whereas these properties were disrupted in the patients with schizophrenia. Brain functional networks have efficient small-world properties which support efficient parallel information transfer at a relatively low cost. More importantly, in patients with schizophrenia the small-world topological properties are significantly altered in many brain regions in the prefrontal, parietal and temporal lobes. These findings are consistent with a hypothesis of dysfunctional integration of the brain in this illness. Specifically, we found that these altered topological measurements correlate with illness duration in schizophrenia. Detection and estimation of these alterations could prove helpful for understanding the pathophysiological mechanism as well as for evaluation of the severity of schizophrenia.

Altered excitatory-inhibitory balance in the NMDA-hypofunction model of schizophrenia

Schizophrenia is a common psychiatric disorder of high incidence, affecting approximately 1% of the world population. The essential neurotransmitter pathology of schizophrenia remains poorly defined, despite huge advances over the past half-century in identifying neurochemical and pathological abnormalities in the disease. The dopamine/serotonin hypothesis has originally provided much of the momentum for neurochemical research in schizophrenia. In recent years, the attention has, however, shifted to the glutamate system, the major excitatory neurotransmitter in the CNS and towards a concept of functional imbalance between excitatory and inhibitory transmission at the network level in various brain regions in schizophrenia. The evidence indicating a central role for the NMDA-receptor subtype in the aetiology of schizophrenia has led to the NMDA-hypofunction model of this disease and the use of phencyclidines as a means to induce the NMDA-hypofunction state in animal models. The purpose of this review is to discuss recent findings highlighting the importance of the NMDA-hypofunction model of schizophrenia, both from a clinical perspective, as well as in opening a line of research, which enables electrophysiological studies at the cellular and network level in vitro. In particular, changes in excitation–inhibition (E/I) balance in the NMDA-hypofunction model of the disease and the resulting changes in network behaviours, particularly in gamma frequency oscillatory activity, will be discussed.

The neuronal pathology of schizophrenia: molecules and mechanisms

There is an accumulation of evidence for abnormalities in schizophrenia of both the major neurotransmitter systems of the brain - those of GABA (gamma-aminobutyric acid) and glutamate. Initial studies have found deficits in the putative neuronal marker, N-acetylaspartate, in a number of brain regions in schizophrenia. The animal models have provided some interesting correlates and discrepancies with these findings. The deficit in inhibitory interneurons within structures implicated in schizophrenic symptomatology may well have direct functional relevance, and can be induced by animal models of the disease such as subchronic phencyclidine administration or social isolation. Their association with these animal models suggests an environmental involvement. A loss of glutamatergic function in schizophrenia is supported by decreases in markers for the neuronal glutamate transporter in striatal structures that receive cortical glutamatergic projections. Deficits in the VGluT1 (vesicular glutamate transporter-1) in both striatal and hippocampal regions support this observation, and the association of VGluT1 density with a genetic risk factor for schizophrenia points to genetic influences on these glutamatergic deficits. Further studies differentiating neuronal loss from diminished activity and improved models allowing us to determine the temporal and causal relationships between GABAergic and glutamatergic deficits will lead to a better understanding of the processes underlying the neuronal pathology of schizophrenia.

The Human Homolog of the QKI Gene Affected in the Severe Dysmyelination “Quaking” Mouse Phenotype: Downregulated in Multiple Brain Regions in Schizophrenia

The Human Homolog of the QKI Gene Affected in the Severe Dysmyelination “Quaking” Mouse Phenotype: Downregulated in Multiple Brain Regions in Schizophrenia

The Human Homolog of the QKI Gene Affected in the Severe Dysmyelination “Quaking” Mouse Phenotype: Downregulated in Multiple Brain Regions in Schizophrenia

The authors sought to understand the origins of oligodendrocyte/myelin gene expression abnormalities in the brains of persons with schizophrenia. Twelve cortical regions (Brodmann's areas 8, 10, 44, 46, 23/31, 24/32, 20, 21, 22, 36/28, 7, and 17) and three noncortical regions (caudate, hippocampus, and putamen) of 16 elderly schizophrenia patients and 14 matched comparison subjects were examined using 450 separate microarrays. The mRNA levels of QKI and its isoforms were then measured in a larger cohort by using quantitative real-time polymerase chain reaction (qPCR) in the cingulate cortex of schizophrenia subjects and matched comparison subjects. Expression of QKI mRNA was decreased in seven cortical regions and the hippocampus in the schizophrenia subjects. QKI gene expression deficits detected by microarray were validated by qPCR in the cingulate cortex, where the expression of isoforms QKI-5, QKI-6, and QKI-7 were profoundly perturbed in schizophrenia. Since QKI plays a fundamental role in oligodendrocyte differentiation and in myelination, its underexpression may be pivotal to, and upstream of, other myelin-associated gene expression abnormalities in schizophrenia. Given the role of QKI in determination of oligodendrocyte fate, these results not only confirm oligodendrocyte-related gene expression abnormalities in schizophrenia but suggest that the physiology of glial progenitor cells may be altered in schizophrenia.

Glutamatergic mechanisms in schizophrenia: Current concepts

Schizophrenia is a severe mental illness affecting millions of people worldwide, with a substantial impact on patients, family, and society. Recent studies have established support for a hypothesis of abnormal glutamatergic neurotransmission in specific brain regions in schizophrenia involving myriad molecules associated with glutamate signaling. After a brief description of these molecules of the glutamatergic synapse, this review focuses on recent experimental evidence for glutamate abnormalities in schizophrenia, and discusses data from genetic, postmortem brain, in vivo imaging, and pharmacologic studies. These convergent findings implicate altered glutamate neurotransmission in the pathophysiology of schizophrenia, and suggest that novel therapeutic strategies targeted at modulation of glutamate neurotransmission may be useful in this illness.

Regional Deficits in Brain Volume in Schizophrenia: A Meta-Analysis of Voxel-Based Morphometry Studies

Voxel-based morphometry is a method for detecting group differences in the density or volume of brain matter. The authors reviewed the literature on use of voxel-based morphometry in schizophrenia imaging research to examine the capabilities of this method for clearly identifying specific structural differences in patients with schizophrenia, compared with healthy subjects. The authors looked for consistently reported results of relative deficits in gray and white matter in schizophrenia and evaluated voxel-based morphometry methods in order to propose a future strategy for using voxel-based morphometry in schizophrenia research. The authors reviewed all voxel-based morphometry studies of schizophrenia that were published to May 2004 (15 studies). The studies included a total of 390 patients with a diagnosis of schizophrenia and 364 healthy volunteers. Gray and white matter deficits in patients with schizophrenia, relative to healthy comparison subjects, were reported in a total of 50 brain regions. Deficits were reported in two of the 50 regions in more than 50% of the studies and in nine of the 50 regions in one study only. The most consistent findings were of relative deficits in the left superior temporal gyrus and the left medial temporal lobe. Use of a smaller smoothing kernel (4-8 mm) led to detection of a greater number of regions implicated in schizophrenia. This review implicates the left superior temporal gyrus and the left medial temporal lobe as key regions of structural difference in patients with schizophrenia, compared to healthy subjects. The diversity of regions reported in voxel-based morphometry studies is in part related to the choice of variables in the automated process, such as smoothing kernel size and linear versus affine transformation, as well as to differences in patient groups. Voxel-based morphometry can be used as an exploratory whole-brain approach to identify abnormal brain regions in schizophrenia, which should then be validated by using region-of-interest analyses.

Differential involvement of 5-HT projections within the amygdala in prepulse inhibition but not in psychotomimetic drug-induced hyperlocomotion

While there is abundant evidence for a role of 5-HT and the amygdala in anxiety and depression, the role of 5-HT in this brain region in schizophrenia is less well understood. We therefore examined the effects of local 5-HT depletion in the amygdala on psychotomimetic drug-induced locomotor hyperactivity and prepulse inhibition, two animal model of aspects of schizophrenia. Pentobarbital-anaesthetized (60 mg/kg, i.p.) male Sprague-Dawley rats were stereotaxically micro-injected with 0.5 μl of a 5 μg/μl solution of the 5-HT neurotoxin 5,7-dihydroxytryptamine (5,7-DHT) into either the basolateral (BLA) or central nucleus of amygdala (CeN). Two weeks after the surgery, rats with BLA lesions did not show changes in either psychotomimetic drug-induced locomotor hyperactivity or prepulse inhibition. In contrast, rats with CeN lesions showed significant disruption of prepulse inhibition, but no changes in psychotomimetic drug-induced locomotor hyperactivity. Neurochemical analysis and autoradiographic labelling of 5-HT transporter sites showed that a good degree of anatomical selectivity was obtained. Following administration of 5,7-DHT into the amygdala, the concentration of 5-HT was significantly reduced. Similarly, 5-HT transporter autoradiographs showed differential and selective lesions of 5-HT innervation in targeted subregions of the amygdala. These results provide evidence for differential involvement of 5-HT projections within the amygdala in prepulse inhibition but not locomotor hyperactivity. Thus, the present study supports the view that 5-HT in the amygdala may be involved in aspects of schizophrenia and a target for antipsychotic drug action.

Variations in myelin and oligodendrocyte-related gene expression across multiple brain regions in schizophrenia: A gene ontology study

Large-scale gene expression studies in schizophrenia (SZ) have generally focused on the dorsolateral prefrontal cortex. Studies of other brain regions have been less frequent and have rarely been performed in the same subjects. We analyzed postmortem gene expression in multiple cortical regions (Brodmann areas 8, 10, 44, 46, 23/31, 24/32, 20, 21, 22, 36/28, 7 and 17, respectively) as well as in the hippocampus, caudate nucleus, and putamen of 13 SZ and 13 control subjects using Affymetrix GeneChip® microarrays. The superior temporal cortex (BA22) and cingulate cortices (BA24/32, 23/31) of subjects with SZ demonstrated more profound alterations of gene expression than other brain regions compared to controls [Katsel, P., Davis, K.L., Gorman, J.M., Haroutunian, V., in press. Variations in differential gene expression patterns across multiple brain regions in schizophrenia. Schizophr. Res.]. Functional categorization of genes whose expression was altered revealed multiple gene ontology classes that included oligodendrocyte/myelin-related genes. These myelin-related ontologies were among the top scored categories in temporal and cingulate gyri and in the hippocampus relative to other brain regions. The most altered transcripts in SZ were those encoding for proteins involved in determination of glial differentiation, myelin structure and adhesion proteins participating in axoglial contacts. Hierarchical clustering demonstrated that these myelin-related gene expression abnormalities in SZ were most pronounced in the hippocampus, superior temporal and cingulate cortices. The high representation of abnormally expressed oligodendrocyte/myelin genes in brain regions with the largest numbers of abnormally expressed genes in SZ confirmed their involvement in the disease process and suggested that the integrity of axon–myelin interaction may be impaired in SZ.

Functional imaging evidence of the relationship between recurrent psychotic episodes and neurodegenerative course in schizophrenia

It remains controversial as to what determines the neurodegenerative course in schizophrenia. This study administered a modified version of the Stroop task and investigated the relationship between functional magnetic resonance imaging (fMRI) signal changes in dysfunctioned task-related regions and clinical course variables. Functional MRI data during task performance were acquired from 10 right-handed schizophrenic patients (mean ± SD age = 29.2 ± 10.3 years, range of illness duration = 0.8–14 years, number of episodes = 1–5) and 10 healthy controls (mean ± SD age = 30.3 ± 6.4). Imaging data were investigated on a voxel-by-voxel basis for single group analysis and for between-group analysis according to the random effect model using Statistical Parametric Mapping (SPM 99b). Correlation analysis with age as a covariate identified those brain regions whose fMRI signal changes were significantly related to clinical course variables in schizophrenia. The number of psychotic episodes was negatively correlated with the fMRI signal change in the right inferior frontal and the right frontal precentral gyri among the activated regions during the Stroop task in schizophrenia, whereas the length of illness was not so correlated. The number of psychotic episodes was also negatively correlated with the fMRI signal change in the left paracingulate in which functional activity was diminished in the patients relative to the controls. Our results indicate that recurrent psychotic episodes are related to the neurodegenerative course in some dysfunctional brain regions in schizophrenia.

Variations in differential gene expression patterns across multiple brain regions in schizophrenia

Large-scale gene expression studies in schizophrenia (SZ) have generally focused on the dorsolateral prefrontal cortex. Despite a wealth of evidence implicating multiple other brain regions in the disease, studies of other brain regions have been less frequent and have rarely been performed in the same subjects. We analyzed postmortem gene expression in the frontal, cingulate, temporal, parietal and occipital cortices (Brodmann areas 8, 10, 44, 46, 23/31, 24/32, 20, 21, 22, 36/28, 7 and 17, respectively) as well as in the hippocampus, caudate nucleus and putamen of persons with schizophrenia and control subjects ( N's = 13) using Affymetrix GeneChip® microarrays. Under identical data filtering conditions, the superior temporal cortex (BA22) of schizophrenia subjects showed the maximal number of altered transcripts (∼ 1200) compared to controls. Anterior and posterior cingulate cortices (BA23/31, 24/32) and the hippocampus followed the superior temporal cortex with two-times lower numbers of altered transcripts. The dorsolateral prefrontal cortex (BA46), a frequent target of SZ-associated studies, showed substantially fewer altered transcripts (∼ 33). These regional differences in differentially expressed genes could not be accounted for by factors such as total numbers of genes expressed or the filtering conditions and criteria used for identification of differentially expressed genes. These findings suggest that the temporal and cingulate cortices and the hippocampal formation represent brain regions of particular abnormality in SZ and may be more susceptible to the disease process(es) than other regions thus far studied.