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At least 55 records · Page 3Linked to original sources
PubMed2000

Features of structural brain abnormality detected in first-episode psychosis.

OBJECTIVE: Structural magnetic resonance imaging (MRI) studies that focus on first-episode psychosis avoid some common confounds, such as chronicity of illness, treatment effects, and long-term substance abuse. However, such studies may select subjects with poor short-term treatment response or outcome. In this study, the authors focus on structural brain abnormalities in never or minimally treated patients who underwent MRI scanning early in their first episode of psychosis. METHOD: The authors examined 37 patients (13 medication naive, 24 previously treated) who were experiencing their first episode of psychosis; the mean duration of symptoms was short (31 weeks). These patients were comparable in age, gender, handedness, ethnicity, and parental socioeconomic status to a group of 25 healthy comparison subjects. A three-dimensional, inversion recovery prepared, fast spoiled gradient/recall in the steady state scan of the whole brain that used 1.5-mm contiguous sections was performed to acquire a T(1)-weighted data set. Human ratings of volumetric measurement of brain structures were performed with stereological techniques on three-dimensional reconstructed MRIs. RESULTS: The patient group had significant deficits in cortical gray matter, temporal lobe gray matter, and whole brain volume as well as significant enlargement of the lateral and third ventricles. Structural deviations were found in both treatment-naive and minimally treated subjects. No relationships were found between any brain matter volumes and positive or negative symptoms. CONCLUSIONS: Structural brain abnormalities were distributed throughout the cortex with particular decrement evident in gray matter. This feature is consistent with altered cell structure and disturbed neuronal connectivity, which accounts for the functional abnormality of psychosis.

Adult↗
PubMed2000

Structural brain imaging and the prevention of schizophrenia: can we identify neuroanatomical markers for young people at risk for the development of schizophrenia?

OBJECTIVE: To examine the potential role of measures derived from structural brain imaging as phenotypic markers for the development of schizophrenia. METHOD: Literature review of results of MRI-based assessments of brain structure in patients with schizophrenia, their first-degree relatives and factors that affect interpretation of such results. RESULTS: Reliable differences in brain structure can be detected in patients with schizophrenia, including those experiencing a first episode of psychosis. Further research is required to determine whether these differences are progressive, how they relate to potential confounding factors such as comorbid substance abuse and the functional consequences of the relatively subtle changes observed. CONCLUSIONS: Further research is needed before structural brain change can be considered as a phenotypic marker for those at risk of developing schizophrenia. Large-scale collaborative research in clinical and normal volunteer groups using standardised assessment protocols would enable the early identification of those findings with predictive power in at-risk populations.

Adolescent↗
PubMedDate not supplied

[Nonspecific brain structures and specialization in the central nervous system].

It has been demonstrated that corticofugal influences may exert selective control of single sensory signals which converge on the neurons of the striatum and other non-specific structures of the brain. This finding suggests that complex sensory image may be formed not by assembling separate elementary signals, but rather by a selective control of these signals into a total sensory inflow within the network brain structures. This conclusion is confirmed by comparative anatomical data. In the phylogenesis of vertebrates, brain structures differentiate presumably into both the specific ones which perform the analysis of only the given kind of information, and those (conventionally described as non-specific) which are specialized on sensory integration and exhibit functional polymodality.

Animals↗
PubMed2005

Late-onset dementia: structural brain damage and total cerebral blood flow.

PURPOSE: To prospectively compare indicators of structural brain damage and total cerebral blood flow in patients with late-onset dementia, subjects of the same age with optimal cognitive function, and young subjects. MATERIALS AND METHODS: The institutional ethics committee approved the studies, and all participants (or their guardians) gave informed consent. The test group included 17 patients older than 75 years (four men, 13 women; median age, 83 years) and with a diagnosis of dementia according to the criteria of the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition. The control group included 16 subjects (four men, 12 women; median age, 87 years) with optimal cognitive function, who were selected from among 599 elderly subjects enrolled in a population-based follow-up study, and 15 young healthy subjects (seven men, eight women; median age, 29 years). Measurements of intracranial and total brain volumes, structural brain damage, and cerebral blood flow were obtained with magnetic resonance imaging. Mean values were compared with the t test; medians, with the Mann-Whitney U test. RESULTS: Values for total brain volume were significantly smaller in elderly subjects (P < .001) but did not differ significantly between patients with dementia and subjects of the same age with optimal cognitive function (P = .69). Among the elderly, significantly higher scores for number and extent of white matter areas of signal hyperintensity (P = .028) and lower magnetization transfer ratios (P = .016) indicated greater structural brain damage in those with dementia. Cerebral blood flow was 246 mL/min lower (P < .001) in elderly subjects than in young subjects. In patients with dementia, cerebral blood flow was 108 mL/min lower than that in subjects of the same age with optimal cognitive function (551 vs 443 mL/min, P < .001). CONCLUSION: The combined observations of more structural brain damage and lower cerebral blood flow in demented elderly individuals than in subjects of the same age with optimal cognitive function support the hypothesis that vascular factors contribute to dementia in old age.

Aged↗
PubMed2004

Segmentation of brain structures in presence of a space-occupying lesion.

Brain deformations induced by space-occupying lesions may result in unpredictable position and shape of functionally important brain structures. The aim of this study is to propose a method for segmentation of brain structures by deformation of a segmented brain atlas in presence of a space-occupying lesion. Our approach is based on an a priori model of lesion growth (MLG) that assumes radial expansion from a seeding point and involves three steps: first, an affine registration bringing the atlas and the patient into global correspondence; then, the seeding of a synthetic tumor into the brain atlas providing a template for the lesion; finally, the deformation of the seeded atlas, combining a method derived from optical flow principles and a model of lesion growth. The method was applied on two meningiomas inducing a pure displacement of the underlying brain structures, and segmentation accuracy of ventricles and basal ganglia was assessed. Results show that the segmented structures were consistent with the patient's anatomy and that the deformation accuracy of surrounding brain structures was highly dependent on the accurate placement of the tumor seeding point. Further improvements of the method will optimize the segmentation accuracy. Visualization of brain structures provides useful information for therapeutic consideration of space-occupying lesions, including surgical, radiosurgical, and radiotherapeutic planning, in order to increase treatment efficiency and prevent neurological damage.

Algorithms↗
PubMed2001

Prospective evaluation of the brain in asymptomatic children with neurofibromatosis type 1: relationship of macrocephaly to T1 relaxation changes and structural brain abnormalities.

BACKGROUND AND PURPOSE: Mutation of the neurofibromatosis type 1 (NF-1) gene may be associated with abnormal growth control in the brain. Because macrocephaly could be a sign of abnormal brain development and because 30% to 50% of children with NF-1 display macrocephaly in the absence of hydrocephalus, we sought to determine the relationship between macrocephaly and other brain abnormalities in young subjects with NF-1. These subjects were free of brain tumor, epilepsy, or other obvious neurologic problems. METHODS: We prospectively screened 18 neurologically asymptomatic subjects with NF-1, ages 6 to 16 years, using clinical measures, psychometric testing, conventional MR imaging, and quantitative MR imaging to measure T1. RESULTS: Cranial circumference was 2 or more SDs above the age norm in seven (39%) of 18 subjects, a frequency of macrocephaly 17-fold higher than normal. Conventional MR imaging showed abnormalities in all 18 children, although there were more extensive abnormalities in subjects with macrocephaly. Macrocephaly in NF-1 was associated with enlargement of multiple brain structures, and brain T1 in macrocephalic subjects was reduced with respect to controls in the genu, frontal white matter, caudate, putamen, thalamus, and cortex. In normocephalic subjects, T1 was reduced only in the genu and splenium. Volumetric analysis showed that macrocephaly was associated specifically with enlargement of white matter volume. CONCLUSION: Neurologically asymptomatic children with NF-1 showed macrocephaly, cognitive deficit, enlarged brain structures, and abnormally low brain T1. Macrocephaly in children with NF-1 may be associated with characteristic alterations in brain development, marked by more widespread and significant changes in T1, greater enlargement of midline structures, and greater volume of white matter.

Adolescent↗
PubMed2000

Mosaic evolution of brain structure in mammals.

The mammalian brain comprises a number of functionally distinct systems. It might therefore be expected that natural selection on particular behavioural capacities would have caused size changes selectively, in the systems mediating those capacities. It has been claimed, however, that developmental constraints limited such mosaic evolution, causing co-ordinated size change among individual brain components. Here we analyse comparative data to demonstrate that mosaic change has been an important factor in brain structure evolution. First, the neocortex shows about a fivefold difference in volume between primates and insectivores even after accounting for its scaling relationship with the rest of the brain. Second, brain structures with major anatomical and functional links evolved together independently of evolutionary change in other structures. This is true at the level of both basic brain subdivisions and more fine-grained functional systems. Hence, brain evolution in these groups involved complex relationships among individual brain components.

Animals↗
PubMed1993

What brain structures are active during emotions? Effects of brain stimulation elicited aversion on c-fos immunoreactivity and behavior.

Aversive behavior is produced by stimulating some brain structures, such as the dorsal periaqueductal gray and the medial hypothalamus. We have used c-fos immunoreactivity to map brain areas which are influenced by stimulation of these two structures. Stimulation was produced in freely moving rats by electrical stimulation or by microinjections of either excitatory amino acids or GABA blocking drugs. Behavior was monitored to detect emotional changes. The effects on labeling induced by the stimulation of either structure were then compared. Structures labeled include the amygdala, the stria terminalis, the supramamillary area, the hypothalamus, the periaqueductal gray, the superior colliculus, the nucleus cuneiformis, and the locus coeruleus. Regardless whether chemical or electrical stimulation was used or the structure stimulated, there was a large overlap among the brain areas labeled. We then compared our results with data from the literature where other methods of inducing aversion have been used, including pain and stress. There was remarkable similarity in the patterning of labeling irrespective of the type of stimulation (central-peripheral, chemical-electrical). There was, however, one interesting difference produced by central vs. peripheral stimulation. Labeling was unilateral in the former case and bilateral in the latter case. Our results suggest that there is a neural substrate that mediates aversive behavior, no matter how it is produced. Nevertheless, that peripheral stimulation produces mainly bilateral activation of this substrate whereas central stimulation produces mainly unilateral activation suggests that natural peripheral stimuli are also integrated at a higher functional level. Future work could be directed toward explicit comparisons of central versus peripheral stimulation to identify the structures involved in higher level integration of aversive behavior.

Animals↗
PubMed1990

Computerized volume measurement of brain structure.

Morphometric analysis of brain structures recently has become a main focus of interest in studies of some neuropsychiatric diseases. Limitations in imaging and mensuration methodology that is available currently for quantitative measurement of anatomic structures have prompted the development of a computerized system to study brain morphometry. A menudriven semi-automated computer system has been developed to assess in vivo brain morphometry using three-dimensional (3-D) magnetic resonance (MR), gradient echo, contiguous images of the whole brain. Accuracy of the system was tested with phantoms creating white on black contrast to simulate the brain tissue surrounded by subarachnoid cerebrospinal fluid (CSF), and a second set of phantoms creating black on white contrast to simulate the ventricular system in the brain tissue. The first set of phantoms was composed of three water-filled balloons (spherical, elliptical, and multiform) and a fresh postmortem brain. The second set of phantoms consisted of three rods of different diameters from a simple geometric plexiglass rod phantom and a life size cast of a human ventricular phantom. System accuracy was generally within 2.0% of the true volumes. System reliability was evaluated in three patient populations; 12 patients with Alzheimer's disease, nine with schizophrenia and nine healthy controls age-matched to the patients with Alzheimer's disease. Two independent observers measured the ventricular systems of these patients. Reliability of the system was addressed by the correlation between the two sets of measurements. For the sample as a whole, and each of the subgroups, the correlation between the two observers was 0.99. This system compares favorably with other morphometric methods reported.

Cerebral Ventricles↗
PubMed2001

Accuracy and reproducibility of simple cross-sectional linear and area measurements of brain structures and their comparison with volume measurements.

Volumetric measurement of brain structure on brain images is regarded as a gold standard, yet is very time consuming. We wondered whether simple linear and area measurements might be as accurate and reproducible. Two observers independently measured the cross-sectional area of the corpus callosum, lentiform and caudate nuclei, thalamus, amygdalas, hippocampi, lateral and third ventricles, and the width of the sylvian and frontal interhemispheric fissures and brain stem on brain MRI of 55 patients using a program written in-house; one observer also measured the volumes of the basal ganglia, amygdalo-hippocampal complex and ventricular system using Analyze, and performed qualitative assessment of four regions (lateral and third ventricles, cortex, and medial temporal lobe) using the Lieberman score. All measures were performed blinded to all other information. Test objects of known size were also imaged with MRI and measured by the two observers using the in-house program. The true sizes of the test objects were measured using engineering calipers by two observers blind to the MRI results. Differences between the two observers using the same measurement method, and one observer using different methods, were calculated. The simple linear and cross-sectional area measurements were rapid (20 min versus 5 h for volumetric); were highly accurate for test-object measurement versus true size; had excellent intraobserver reliability; and, for most brain structures, the simple measures correlated highly significantly with volumetric measures. The simple measures were in general highly reproducible, the difference (as a percentage of the area or width of a region) between the two raters being around 10%, range 0.1%-14.1%, (similar to inter-rater variability in previous studies of volume measurements). The simple linear and area measures are reproducible and correlate well with the measured volumes, and there is a considerable time saving with the former. In circumstances where a large volume of work precludes detailed volume measurement, simple methods are reliable and can be used instead.

Brain↗
PubMed2002

Brain morphology in antipsychotic-naïve schizophrenia: a study of multiple brain structures.

BACKGROUND: Although brain volume changes are found in schizophrenia, only a limited number of structural magnetic resonance imaging studies have exclusively examined antipsychotic-naïve patients. AIMS: To comprehensively investigate multiple brain structures in a single sample of patients who were antipsychotic-naïve. METHOD: Twenty antipsychotic-naïve patients with first-episode schizophrenia and 20 healthy comparison subjects were included. Intracranial, total brain, frontal lobe, grey and white matter, cerebellar, hippocampal, parahippocampal, thalamic, caudate nucleus and lateral and third ventricular volumes were measured. Repeated-measures analyses of (co)variance were conducted with intracranial volume as covariate. RESULTS: Third ventricle volume enlargement was found in patients compared with the healthy subjects. No differences were found in other brain regions. CONCLUSIONS: These findings suggest that some brain abnormalities are present in the early stages of schizophrenia. Moreover, it suggests that brain abnormalities reported in patients with chronic schizophrenia develop in a later stage of the disease and/or are medication induced.

Adolescent↗
PubMed2004

Integrating databases and expert systems for the analysis of brain structures: connections, similarities, and homologies.

The NeuroHomology Database system (NHDB) combines databases related to brain structures from different species with different knowledge management systems (KMSs) for systematization, evaluation and processing neurobiological data. Special attention is assessment of similarity of data from different species as a basis for exploring neural homologies. NHDB includes modules that handle brain structure and connectivity data, as well as inference engines for evaluation of the stored neurobiological information. The spatial inference engine evaluates the possible topological relations between cortical structures in different neuroanatomical atlases. The connectivity inference engine evaluates the reliability of information pertaining to fiber tracts as those are reflected in the literature. The inference engine for translation of neuroanatomical connections in different atlases evaluates the probability of existence of connections of interest in different parcellation schemes. Finally, the similarity inference engine calculates the overall degree of similarity of pairs of brain structures from different species by taking into account a set of eight criteria. We present examples of search for information in NHDB system, inferences of relations between cortical structures from equivalent neuroanatomical atlases, reconstruction of functional networks of brain structures from data collated from the literature, translation of connectivity matrices in equivalent parcellation schemes, and evaluations of similarities of brain structures from humans, macaques and rats.

Algorithms↗
PubMed2005

Genetics of brain structure and intelligence.

Genetic influences on brain morphology and IQ are well studied. A variety of sophisticated brain-mapping approaches relating genetic influences on brain structure and intelligence establishes a regional distribution for this relationship that is consistent with behavioral studies. We highlight those studies that illustrate the complex cortical patterns associated with measures of cognitive ability. A measure of cognitive ability, known as g, has been shown highly heritable across many studies. We argue that these genetic links are partly mediated by brain structure that is likewise under strong genetic control. Other factors, such as the environment, obviously play a role, but the predominant determinant appears to be genetic.

Animals↗
PubMedDate not supplied

[Use of "non-standard" young rabbits of the chinchilla breed for determination of the stereotaxic coordinates of brain structures].

It has been found that differences in the distances from the brain structures to orienting points on the scull of non-standard rabbits considerably exceed those in the distances between the brain structures of the same animals. In non-standard rabbits of one and the same age, the quantitative differences of the rostral or caudal location of all brain structures in relation to the bone orienting points are more significant than those in the lengths of the brain. Intravital determination of a point on the surface of the scull with horizontal coordinates of the anterior commissure is suggested for selection of young rabbits with a normal location of brain structures in regard to the zero point (bregma ) as well as for introduction of corrections in the location of the zero points. It is also suggested that this point be used directly as the zero point of reading the coordinates instead of the bregma.

Age Factors↗
PubMed1997

Distribution of Glut1 glucose transporters in different brain structures compared to glucose utilization and capillary density of adult rat brains.

Glut1 is a specific transporter system that mediates glucose transfer across the blood-brain barrier (BBB). Although the main location of Glut1 is in the capillary endothelium of the brain, its local distribution in different brain regions is not as well defined. In the present investigation, the local pattern of Glut1 distribution was determined in 13 brain structures using an immunoautoradiographic method developed for this purpose. A polyclonal antibody directed against the C-terminal amino acid sequence of Glut1 was applied to cryosections of rat brains. A secondary antibody was added that had been coupled to [35S]. Results show a heterogeneous distribution of Glut1 in the brain with activities of [35S] ranging from 65% below to 15% above the mean. White matter activity was lower than gray matter activity. For comparison, capillary sections were counted in corresponding cryosections by indirect immunofluorescence using fibronectin antibodies. In addition, local cerebral glucose utilization (LCGU) was analyzed in identical brain structures of conscious rats by the quantitative autoradiographic 2-deoxyglucose method. Significant correlations were found between Glut1 density and either LCGU or capillary density. Results indicate a tight coupling of Glut1 transporter density and capillary density to the LCGU of different BBB structures in adult rats.

Animals↗
PubMed1999

Structural brain imaging in schizophrenia: a selective review.

Structural neuroimaging studies have provided some of the most consistent evidence for brain abnormalities in schizophrenia. Since the initial computed tomography study by Johnstone and co-workers, which reported lateral ventricular enlargement in schizophrenia, advances in brain imaging technology have enabled further and more refined characterization of abnormal brain structure in schizophrenia in vivo. This selective review discusses the major issues and findings in structural neuroimaging studies of schizophrenia. Among these are evidence for generalized and regional brain volume abnormalities, the specificity of anatomic findings to schizophrenia and to men versus women with schizophrenia, the contribution of genetic influences, and the timing of neuroanatomic pathology in schizophrenia. The second section reviews new approaches for examining brain structure in schizophrenia and their applications to studies on the pathophysiology of schizophrenia.

Brain↗
PubMed2004

Review of cognition and brain structure in schizophrenia: profiles, longitudinal course, and effects of treatment.

Research on the cognitive and brain structural correlates of schizophrenia has seen tremendous progress over the past decade. It has become increasingly clear that there is no pathognomic neuropsychological or structural neuroanatomic profile in schizophrenia, likely due in part to etiological heterogeneity within the disorder. Nonetheless, several studies have indicated that verbal episodic memory and vigilance deficits are particularly prominent, and are observed even in untreated patients in their first episode of the disorder. The course of schizophrenia appears to be somewhat variable, and factors that contribute to the development of the illness, and in some patients, deterioration of cognitive functioning, have not been elucidated clearly. Neurodevelopmental factors, however, likely play an important role in the diathesis of the disorder, while neuropathological processes contribute to deterioration and progression. At this time, there are relatively few controlled comparisons of the cognitive effects of atypical and conventional antipsychotic medications. Additional studies of the potential effects of antipsychotic medications on structural brain abnormalities are warranted. It is hoped that newer innovative psychopharmacological approaches and neuropsychological remediation programs will, in the not-too-distant future, provide clinicians with a variety of means to improve the cognitive and social functioning of their patients.

Antipsychotic Agents↗