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Systematic evaluation of cortical differences between humans and macaques calls for inter-species registration of the cortex that matches homologous regions across species. For establishing homology across brains, structural landmarks and biological features have been used without paying sufficient attention to functional homology. The present study aimed to determine functional homology between the human and macaque cortices, defined in terms of functional network properties, by proposing an iterative functional network-based registration scheme using surface-based spherical demons. The functional connectivity matrix of resting-state functional magnetic resonance imaging (rs-fMRI) among cortical parcellations was iteratively calculated for humans and macaques. From the functional connectivity matrix, the functional network properties such as principal network components were derived to estimate a deformation field between the human and macaque cortices. The iterative registration procedure updates the parcellation map of macaques, corresponding to the human connectome project's multimodal parcellation atlas, which was used to derive the macaque's functional connectivity matrix. To test the plausibility of the functional network-based registration, we compared cortical registration using structural versus functional features in terms of cortical regional areal change. We also evaluated the interhemispheric asymmetry of regional area and its inter-subject variability in humans and macaques as an indirect validation of the proposed method. Higher inter-subject variability and interhemispheric asymmetry were found in functional homology than in structural homology, and the assessed asymmetry and variations were higher in humans than in macaques. The results emphasize the significance of functional network-based cortical registration across individuals within a species and across species., Competing Interests: The authors have declared that no competing interests exist.

The resting-state brain is often considered a nonlinear dynamic system transitioning among multiple coexisting stable states. Despite the increasing number of studies on the multistability of the brain system, the processes of state transitions have rarely been systematically explored. Thus, we investigated the state transition processes of the human cerebral cortex system at rest by introducing a graph-theoretical analysis of the state transition network. The energy landscape analysis of brain state occurrences, estimated using the pairwise maximum entropy model for resting-state fMRI data, identified multiple local minima, some of which mediate multi-step transitions toward the global minimum. The state transition among local minima is clustered into two groups according to state transition rates and most inter-group state transitions were mediated by a hub transition state. The distance to the hub transition state determined the path length of the inter-group transition. The cortical system appeared to have redundancy in inter-group transitions when the hub transition state was removed. Such a hub-like organization of transition processes disappeared when the connectivity of the cortical system was altered from the resting-state configuration. In the state transition, the default mode network acts as a transition hub, while coactivation of the prefrontal cortex and default mode network is captured as the global minimum. In summary, the resting-state cerebral cortex has a well-organized architecture of state transitions among stable states, when evaluated by a graph-theoretical analysis of the nonlinear state transition network of the brain., Competing Interests: The authors have declared that no competing interests exist.

During brain modulation, repeated mental practice may not always result in efficient learning. Particularly, the effectiveness of mental motor practice depends on how well one induces neural activity in a desired state consistently across mental trials, which calls for feedbacks to adjust one's performance. We hypothesized that even a brief experience of neurofeedback learning enhances trial-by-trial neural pattern consistency during subsequent mental motor execution and that this experience would change recruitment of functional connectivity in the motor imagery and default mode networks. To test this hypothesis, we conducted an experiment with two sessions of mental motor practice before and after a neurofeedback training session, in which participants conducted four types of first-person mental motor execution tasks (walking forward, turning left, turning right, and touching a tree). During the neurofeedback training session, in which participants conducted a virtual navigation game, 10 experimental participants received real-time fMRI neuro-feedbacks, while 10 control participants simply repeated the same mental task according to given cues without feedbacks. The experimental group showed significantly higher effects of neuro-feedback training on trial-by-trial consistencies and classification accuracies of activated neural patterns than the control group. Task-performing global node strength and network efficiency were increased in the motor imagery network but decreased in the default mode network only in the experimental group. These results demonstrate that even a brief experience of feedback learning is more effective than simple practice repetitions without evaluation, which was reflected in increased neural pattern consistency and task-dependent functional connectivity during a mental motor execution task., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Background: In the tradition of phenomenology, minimal selfdisturbance has been suggested as a manifestation of the core pathogenesis of schizophrenia; however, the underlying neural mechanism remains unclear. Here, in line with the concept of "cognitive dysmetria," we investigated the cerebro-cerebellar default mode network (DMN) connectivity and its association with pre-reflective minimal selfdisturbance in individuals at ultra-high risk (UHR) for psychosis and patients with first-episode schizophrenia (FES)., Methods: Thirty-three UHR individuals, 18 FES patients, and 56 healthy controls (HCs) underwent functional magnetic resonance imaging during rest at baseline. Seed-based functional connectivity (FC) analysis was performed using the cerebellar DMN seeds from the bilateral Crus I, followed by between-group comparisons. Correlation analysis was conducted to examine the relationship between the cerebro-cerebellar FC and the self-reported severity of minimal self-disturbance in the UHR and FES groups, respectively., Results: FES participants showed significantly reduced cerebellar FC with the left presupplementary motor area (preSMA), right anterior prefrontal cortex (aPFC), and precuneus compared to HCs, while UHR participants showed an intermediate decrease between the other two groups, particularly in the left preSMA and right aPFC. Minimal self-disturbance, which appeared at similar levels in both UHR and FES groups, was significantly associated with cerebro-cerebellar FC, although each group presented different patterns of associations., Conclusions: Aberrant cerebro-cerebellar FC, which may be closely related to minimal self-disturbance, may be able to provide meaningful insights into the real gestalt of schizophrenia and contribute to further research to predict future psychosis in UHR individuals., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Although the relationship between resting-state functional connectivity and task-related activity has been addressed, the relationship between task and resting-state directed or effective connectivity - and its behavioral concomitants - remains elusive. We evaluated effective connectivity under an N-back working memory task in 24 participants using stochastic dynamic causal modelling (DCM) of 7 T fMRI data. We repeated the analysis using resting-state data, from the same subjects, to model connectivity among the same brain regions engaged by the N-back task. This allowed us to: (i) examine the relationship between intrinsic (task-independent) effective connectivity during resting (A rest ) and task states (A task ), (ii) cluster phenotypes of task-related changes in effective connectivity (B task ) across participants, (iii) identify edges (B task ) showing high inter-individual effective connectivity differences and (iv) associate reaction times with the similarity between B task and A rest in these edges. We found a strong correlation between A rest and A task over subjects but a marked difference between B task and A rest . We further observed a strong clustering of individuals in terms of B task , which was not apparent in A rest . The task-related effective connectivity B task varied highly in the edges from the parietal to the frontal lobes across individuals, so the three groups were clustered mainly by the effective connectivity within these networks. The similarity between B task and A rest at the edges from the parietal to the frontal lobes was positively correlated with 2-back reaction times. This result implies that a greater change in context-sensitive coupling - from resting-state connectivity - is associated with faster reaction times. In summary, task-dependent connectivity endows resting-state connectivity with a context sensitivity, which predicts the speed of information processing during the N-back task., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Blunted affect is a relatively enduring schizophrenic symptom and its presence brings about poor functioning and outcomes. Functional impairment in the mirror neuron system which is involved in both motor execution and imitation may be a neural basis of blunted affect, but it is not proved yet. Fifteen patients with schizophrenia and 16 healthy controls performed the facial expression task during functional magnetic resonance imaging. The task was to reproduce facial expressions in response to the face or word stimuli for happiness, sadness, and meaningless expression. Brain activities during facial expressions in patients compared with controls and their relationship with affective flattening were analyzed. Compared to controls, patients exhibited decreased activity in the widespread dorsal frontal regions and increased activity in the ventral frontal and subcortical regions. Patients also demonstrated significant negative correlation of the severity of affective flattening with activities in the mirror neuron system, such as the premotor cortex, motor cortex, and inferior parietal lobule. Emotional expression in patients with schizophrenia may be related to hypoactivity of the dorsal system and hyperactivity of the ventral system. An imbalance of these two systems may contribute to blunted affect. Directly addressing blunted affect using emotional expression provides a new perspective that functional disturbance of the mirror neuron system may play an important role in manifestation of blunted affect in schizophrenia., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Background: Cognitive dysfunction is common in Parkinson's disease (PD), and along with PD with dementia (PDD), the concept of mild cognitive impairment in PD (PD-MCI) has been introduced., Methods: To identify structural candidates according to cognitive status in PD, we compared gray matter (GM) density across PD-intact cognition (PD-IC, n = 23), PD-MCI (n = 27), and PDD (n = 18) using voxel-based morphometry., Results: The demographic data among PD subjects were similar, however, general cognition and disease duration were more severe in PD-MCI and PDD than in PD-IC. Compared with controls, GM density was significantly decreased in the left occipital area in PD-IC; the bilateral temporal, left prefrontal and insular, and right occipital areas in PD-MCI; and in widespread brain areas in PDD. Compared with PD-IC, patients with PD-MCI had significantly decreased GM density in the right middle frontal area, and those with PDD had decreased GM density in the right parietal, middle frontal, insular, and lentiform areas. GM density in patients with PDD was significantly decreased in the bilateral middle temporal, right inferior temporal, and left middle and superior prefrontal areas. PDD patients with shorter disease duration before dementia (<5 year) showed greater GM atrophy in the posterior cingulate area than did those with longer disease duration (≥5 year)., Conclusions: These data suggest that cortical atrophy in PD exhibits a greater extent with increasing levels of cognitive impairment, and different anatomical substrates would correspond to each cognitive status., (Copyright © 2011 Movement Disorder Society.)

Background: Prestimulus EEG alpha activity in humans has been considered to reflect ongoing top-down preparation for the performance of subsequent tasks. Since theta oscillations may be related to poststimulus top-down processing, we investigated whether prestimulus EEG theta activity also reflects top-down cognitive preparation for a stimulus., Results: We recorded EEG data from 15 healthy controls performing a color and shape discrimination task, and used the wavelet transformation to investigate the time course and power of oscillatory activity in the signals. We observed a relationship between both anterior theta and posterior alpha power in the prestimulus period and the type of subsequent task., Conclusions: Since task-differences were reflected in both theta and alpha activities prior to stimulus onset, both prestimulus theta (particularly around the anterior region) and prestimulus alpha (particularly around the posterior region) activities may reflect prestimulus top-down preparation for the performance of subsequent tasks.

Background: Despite clinical and neuropsychological similarities between Parkinson's disease dementia (PDD) and dementia with Lewy bodies (DLB), recent studies have demonstrated that structural and pathological changes are more severe in DLB than in PDD., Methods: 19 patients with probable PDD and 18 patients with probable DLB who had a similar overall severity of dementia and demographic characteristics were examined by a standardised neuropsychological test and voxel-based analysis of fractional anisotropy (FA) using diffusion tensor imaging (DTI)., Results: The patients with DLB performed significantly worse in visual recognition memory, semantic fluency and ideomotor praxis than those with PDD (p<0.05). Compared with controls, the FA value in patients with PDD was significantly lower in bilateral frontal, left temporal and left parietal white matter. In patients with DLB, the pattern of FA reduction was similar to that of patients with PDD; however, white-matter abnormalities were more severe and extended into bilateral insular, bilateral posterior cingular and bilateral visual association regions. In a direct comparison between PDD and DLB, the FA value in patients with DLB was significantly decreased in bilateral posterior temporal, posterior cingular and bilateral visual association fibres extending into occipital areas., Conclusions: Despite global similarities in cognitive performance and white-matter pathology between DLB and PDD patients, those with DLB had more severely impaired frontal and temporal area-associated cognitive subsets, and more severe white-matter pathology in temporal and visual association fibres. These data suggest that differences in the underlying nature of PDD and DLB may exist with global similarities in their cognitive performance and white-matter pathology.

To explore the morphological aspects of the functional reorganization of the blind's visual cortex, we analyzed the regional cortical thickness and cortical surface area in the congenitally blind subjects (CB) compared to the late-onset blind (LB) and sighted controls (SC). Cortical thickness was calculated from high-resolution T1-weighted magnetic resonance images of 21 young CB (blind from birth, mean age=27.1 yr), 12 LB, and 35 young SC. Analysis of covariance of cortical layer thickness with global thickness, age, and gender as covariates was done node-by-node on the entire cortical surface. Further analysis of mean thickness and surface area was performed for 33 automatically parceled cortical regions. Voxel-based morphometry was also conducted to compare results with cortical thickness and surface area. We found increased cortical thickness in the regions involved in vision and eye movement, such as the pericalcarine sulcus, cingulate cortex, and right frontal eye field, but cortical thinning in the left somatosensory cortex and right auditory cortex of CB compared to SC. CB had significantly reduced surface extent in the primary and associated visual areas, which explains volumetric atrophies in the visual cortex of CB despite increased cortical thickness. Conversely, LB tended to have cortical thinning in the primary visual cortex with a slight or no significant reduction in the surface extent. These morphological alterations in CB may indicate cortical reorganization at the visual cortex in connection with other sensory cortices.

Population maps of the corpus callosum (CC) and cortical lobe connections were generated by combining cortical gray matter parcellation with the diffusion tensor fiber tractography of individual subjects. This method is based on the fact that the cortical lobes of both hemispheres are interconnected by the corpus callosal fibers. T1-weighted structural MRIs and diffusion tensor MRIs (DT-MRI) of 22 right-handed, healthy subjects were used. Forty-seven cortical parcellations in the dorsal prefrontal cortex, ventral prefrontal cortex, sensory-motor cortex, parietal cortex, temporal cortex, and occipital cortex were semi-automatically derived from structural MRIs, registered to DT-MRI, and used to identify callosal fibers. The probabilistic connections to each cortex were mapped on entire mid-sagittal CC voxels that had anatomical homology between subjects as determined by spatial registration. According to the population maps of the callosal connections, the ventral prefrontal cortex and parts of the dorsal prefrontal cortex both project fibers through the genu and rostrum. The CC regions through which the superior frontal cortex passes extend into the posterior body. Fibers arising from the parietal lobe and occipital lobe run mainly through the splenium, while fibers arising from the sensory-motor cortex pass through the isthmus. In general, dorsal or medial cortical lobes project fibers through the dorsal region of the CC, while lateral cortical lobes project fibers through the ventral region of the CC. The probabilistic subdivision of the CC by connecting cortical gray matter provides a more precise understanding of the CC., ((Copyright) 2006 Wiley-Liss, Inc.)

Diffusion properties of the thalamocortical pathways were compared between 30 schizophrenic patients and 22 healthy age-matched and sex-matched volunteers. T1-weighted and diffusion tensor images were used for cortical parcellation and probabilistic tractography to generate population-based thalamocortical pathway maps. The weighted fractional anisotropy and the longitudinal and transversal diffusivity of each pathway were calculated for individual participants. Patients with schizophrenia demonstrated decreased anisotropy and increased longitudinal and transversal diffusivity within the pathways from the mediodorsal nucleus and the pulvinar to the orbitofrontal and parietal-occipital-temporal lobes. Anisotropy decreases and diffusivity increases were correlated with positive and negative syndrome scale scores. Alterations in global diffusion properties within the thalamocortical pathways imply the disruption of brain circuitry in schizophrenic patients.

The purposes of this study were to examine the effect of sensitivity encoding (SENSE) factors on cortical thickness measurements and to determine which SENSE factor to use to reliably measure cortical thickness in 3.0 T and 1.5 T T1-weighted MRI images. The 3D T1-TFE images were acquired from 11 healthy volunteers with 6 different SENSE acceleration factors from 1.0 (without SENSE acceleration) to 4.0 on a 1.5 T scanner, and 9 different SENSE factors from 1.0 to 6.0, plus a second-day 1.0 acquisition on a 3.0 T scanner. Cortical thickness was calculated for the entire cortical surface that was further subdivided into 33 regions. Repeated measures multivariate analysis of variance revealed that the main effect of SENSE factors (F=12.485, df=7, p=0.006) was a significant underestimation of cortical thickness at SENSE 5.0 (p=0.022) and 6.0 (p=0.011) at 3.0 T and at SENSE 4.0 (p<0.000) at 1.5 T. Repeated measures ANOVA showed that thickness measurements at the insula, superior temporal sulcus, the medial part of the superior frontal lobe, and cingulate cortex are highly affected by SENSE factors. SENSE factors affect thickness estimation more significantly at 1.5 T and thus 1.5 T imaging provides less reliable estimates using SENSE techniques. Faster imaging can be done without too much loss of reliability using a high SENSE factor, such as 3.0, at 3.0 T with acquisition time being inversely proportional to the SENSE factor.

Critical times of involvement of areas important to working memory were examined both with pitch and audioverbal N-back tasks using single-pulse transcranial magnetic stimulation (TMS). TMS was administered to 12 healthy participants over dorsolateral prefrontal and inferior parietal regions in each hemisphere at four different times after stimulus onset (250, 450, 650, and 850 ms). For the pitch N-back task, interference with working memory, as evidenced by a significant increase in reaction time, was observed with TMS over the right hemisphere regions. In contrast, for the audioverbal N-back task, TMS resulted in significantly increased reaction time only for left inferior parietal TMS delivered 450 ms after stimulus onset. These results imply different hemispheric specializations for pitch and audioverbal working memory.

Objective: The thalamus, which consists of multiple subnuclei, has been of particular interest in the study of schizophrenia. This study aimed to identify abnormalities in the connectivity-based subregions of the thalamus in patients with schizophrenia., Methods: Thalamic volume was measured by a manual tracing on superimposed images of T1-weighted and diffusion tensor images in 30 patients with schizophrenia and 22 normal volunteers. Cortical regional volumes automatically measured by a surface-based approach and thalamic subregional volumes measured by a connectivity-based technique were compared between the two groups and their correlations between the connected regions were calculated in each group., Results: Volume reduction was observed in the bilateral orbitofrontal cortices and the left cingulate gyrus on the cortical side, whereas in subregions connected to the right orbitofrontal cortex and bilateral parietal cortices on the thalamic side. Significant volumetric correlations were identified between the right dorsal prefrontal cortex and its related thalamic subregion and between the left parietal cortex and its related thalamic subregion only in the normal group., Conclusions: Our results suggest that patients with schizophrenia have a structural deficit in the corticothalamic systems, especially in the orbitofrontal-thalamic system. Our findings may present evidence of corticothalamic connection problems in schizophrenia.

Previous studies have shown that maturation of the white matter in terms of its relative signal intensity changes on MRI is almost complete at 2-3 years of age. We hypothesized that quantitative analysis may show maturation of the white matter during childhood and adolescence. In the present study we performed multi-echo T2 relaxometry in 33 healthy subjects (girls, 15; boys, 18) aged 3-15 years. T2 relaxation times of the genu and splenium were measured. In healthy subjects, the T2 relaxation times were significantly correlated with age in both girls (r=0.611, p=.016) and boys (r=0.721, p=.001) in the splenium, but not in the genu (p>.05). To further confirm genu-to-splenium signal intensity ratio changes, a total of 389 brain MRIs were retrospectively selected from the patients who had normal results (189 girls/women, 200 boys/men; age range, 3-20 years). The genu-to-splenium signal intensity ratio was obtained from the T2-weighted images. In patients with normal MRI, the genu-to-splenium signal intensity ratio was significantly decreased with age (p<.001) by 16 years. The T2 relaxation times gradually increase in the splenium during childhood and adolescence, suggestive of maturation.

Context: Structural brain abnormalities, including larger cerebrospinal fluid (CSF) volumes, have been observed in men diagnosed as having schizotypal personality disorder (SPD)., Objectives: To determine whether women with SPD have abnormalities similar to those of men with SPD and to elucidate specific SPD regional volume deficits and symptom correlations., Design: Naturalistic study., Setting and Participants: Thirty neuroleptic-naive women with SPD and 29 female control subjects, both recruited from the community. Participants were group matched for age, parental socioeconomic status, handedness, and IQ., Interventions: A new segmentation method was applied to magnetic resonance images to automatically parcel the images into CSF, gray matter, and white matter. The neocortex was manually separated from subcortical and other nonneocortical structures. Voxel-based morphometry was applied to determine global and regional volume deficits., Main Outcome Measures: Left and right neocortical gray matter, white matter, and CSF relative volumes as well as clinical symptoms from the Structured Interview for Schizotypy and the Schizotypal Personality Questionnaire-Brief Version., Results: Smaller left (3.84%) and right (3.83%) neocortical gray matter relative volumes associated with larger left (9.66%) and right (9.61%) sulcal CSF relative volumes were found in women with SPD compared with controls. Voxel-based morphometry showed that the neocortical deficits in SPD were especially prominent in the left superior and middle temporal gyri, left inferior parietal region with postcentral gyrus, and right superior frontal and inferior parietal gyri. In the SPD group, larger lateral ventricle volumes correlated with more severe symptoms on the Structured Interview for Schizotypy and the Schizotypal Personality Questionnaire-Brief Version., Conclusions: The smaller neocortical gray matter volume and larger sulcal CSF volume provide evidence of the brain basis of this personality disorder and emphasize the communality of brain abnormalities in the schizophrenia spectrum.

The purpose of the study is to propose a new framework for surface-based statistical parametric mapping of PET images using MRI-based cortical surface analysis, including partial volume correction, intensity normalization and spatial normalization on the cortical surface. Maximum PET intensities along the path between inner and outer layer of the cortical gray matter are mapped onto the cortical surface to generate a metabolic activity surface map. For the partial volume correction, the metabolic activity surface map was divided by the partial volume effect map. The regional metabolic activity was normalized by the global activity iteratively calculated at the surface nodes, statistically independent of the group, as measured by F statistics. After surface-based spatial normalization, a statistical evaluation of both cortical thickness and cortical metabolic activity was conducted on the normalized surfaces of 16 patients with schizophrenia and 16 age- and gender-matched healthy controls. The patients with schizophrenia were found to have significant cortical thinning in the temporal and inferior frontal cortices. Accordingly, their PET imaging was significantly affected by the partial volume effect, indicating that partial volume correction could change the statistical results. After correction of the partial volume effects, the patients showed hyperactivity in the temporal cortex, whereas hypoactivity in the prefrontal cortex, predominantly in the left hemisphere. Our results demonstrate that anatomical factors affect an analysis for functional data from the PET, and therefore the importance of combining anatomy and function in the analysis of imaging data for schizophrenia should be considered.

Patients with schizophrenia exhibit deficits in semantic processing, which can form the basis of thought disorders. The objective of this study was to explore functional connectivity between the activated areas during semantic processing in schizophrenia. Twelve patients with schizophrenia and 12 healthy controls were studied with [15O]H2O positron-emission tomography during semantic judgment. The expected activation in the left inferior occipitotemporal cortex significantly correlated with several other regional activations in normal study participants, but with no other regional activations in patients with schizophrenia. This finding suggests that schizophrenia involves a disconnection of semantic networks. The resultant distortion in semantic processing may have an impact on thought disorders.

Life satisfaction is an essential component of subjective well-being and provides a fundamental resource for optimal everyday functioning. The goal of the present study was to examine how life satisfaction influences self-referential processing of emotionally valenced stimuli. Nineteen individuals with high life satisfaction (HLS) and 21 individuals with low life satisfaction (LLS) were scanned using functional MRI while performing a face-word relevance rating task, which consisted of 3 types of face stimuli (self, public other, and unfamiliar other) and 3 types of word stimuli (positive, negative, and neutral). We found a significant group x word valence interaction effect, most strikingly in the dorsal medial prefrontal cortex. In the positive word condition dorsal medial prefrontal cortex activity was significantly higher in the LLS group, whereas in the negative word condition it was significantly higher in the HLS group. The two groups showed distinct functional connectivity of the dorsal medial prefrontal cortex with emotional processing-related regions. The findings suggest that, in response to emotional stimuli, individuals with HLS may successfully recruit emotion regulation-related regions in contrast to individuals with LLS. The difference in functional connectivity during self-referential processing may lead to an influence of life satisfaction on responses to emotion-eliciting stimuli. [ABSTRACT FROM AUTHOR]

We created a spatial probability atlas of schizophrenia to provide information about the neuroanatomic variability of brain regions of patients with the disorder. Probability maps of 16 regions of interest (ROIs) were constructed by taking manually parcellated ROIs from subjects'' magnetic resonance images (MRIs) and linearly transforming them into Talairach space using the Montreal Neurological Institute (MNI) template. ROIs included temporal, parietal, and prefrontal cortex subregions, with a principal focus on temporal lobe structures. Subject Ns ranged from 11 to 28 for the different ROIs. Our global measure of the spatial distribution of the transformed ROI was the sum of voxels with 50% overlap among subjects. The superior temporal gyrus (STG) and fusiform gyrus (FG) had lower values for schizophrenic subjects than for normal controls, suggestive of greater spatial variability for these ROIs in schizophrenic subjects. For the computation of statistical significance of group differences in portions of the ROI, we used voxel-wise comparisons and Fisher''s exact test. First-episode schizophrenic patients compared with controls showed lower probability (P < 0.05) at dorso-posterior areas of planum temporale and Heschl''s gyrus, lateral and anterior regions in the left hippocampus (HIPP), and dorsolateral regions of fusiform gyrus. Importantly, most ROIs of schizophrenic subjects showed a significantly lower spatial overlap than controls, even after nonlinear spatial normalization, suggesting a greater heterogeneity in the spatial distribution of ROIs. There is consequently a need for caution in neuroimaging studies where data from schizophrenic subjects are normalized to a particular stereotaxic coordinate system based on healthy controls. Apparent group differences in activation may simply reflect a greater heterogeneity of spatial distribution in schizophrenia. [Copyright &y& Elsevier]

Abnormal abstract thinking is a major cause of social dysfunction in patients with schizophrenia, but little is known about its neural basis. In this study, we aimed to determine the characteristic abstract thinking-related brain responses in patients using a task reflecting social situations. We conducted functional magnetic resonance imaging while 16 patients with schizophrenia and 16 healthy controls performed a theme-identification task, in which various emotional pictures depicting social situations were presented. Compared with healthy controls, the patients showed significantly decreased activity in the left frontopolar and right orbitofrontal cortices during theme identification. Activity in these two regions correlated well in the controls, but not in patients. Instead, the patients exhibited a close correlation between activity in both sides of the frontopolar cortex, and a positive correlation between the right orbitofrontal cortex activity and degrees of theme identification. Reduced activity in the left frontopolar and right orbitofrontal cortices and the underlying aberrant connectivity may be implicated in the patients’ deficits in abstract thinking. These newly identified features of the neural basis of abnormal abstract thinking are important as they have implications for the impaired social behavior of patients with schizophrenia during real-life situations. [ABSTRACT FROM AUTHOR]

Background: The hippocampus has been shown to be abnormal in schizophrenia. The fornix is one of the main fiber tracts connecting the hippocampus with other brain regions. Few studies have evaluated the fornix in schizophrenia, however. A focus on fornix abnormalities and their association with hippocampal abnormalities might figure importantly in our understanding of the pathophysiology of schizophrenia. Methods: Line-scan diffusion tensor imaging (DTI) was used to evaluate diffusion in the fornix in 24 male patients with chronic schizophrenia and 31 male control subjects. Maps of fractional anisotropy (FA) and mean diffusivity (Dm), which are indices sensitive to white-matter integrity, were generated to quantify diffusion within the fornix. We used high spatial resolution magnetic resonance imaging (MRI) to measure hippocampal volume. Results: FA and cross-sectional area of the fornix were significantly reduced in patients compared with control subjects. Dm was significantly increased, whereas hippocampal volume was bilaterally reduced in patients. Reduced hippocampal volume was correlated with increased mean Dm and reduced cross-sectional area of the fornix for patients. Patients also showed a significant correlation between reduced scores on neuropsychologic measures of declarative-episodic memory and reduced hippocampal volumes. Conclusions: These findings demonstrate a disruption in fornix integrity in patients with schizophrenia. [Copyright &y& Elsevier]