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PubMed2006

Temporal and spatial dynamics of brain structure changes during extensive learning.

The current view regarding human long-term memory as an active process of encoding and retrieval includes a highly specific learning-induced functional plasticity in a network of multiple memory systems. Voxel-based morphometry was used to detect possible structural brain changes associated with learning. Magnetic resonance images were obtained at three different time points while medical students learned for their medical examination. During the learning period, the gray matter increased significantly in the posterior and lateral parietal cortex bilaterally. These structural changes did not change significantly toward the third scan during the semester break 3 months after the exam. The posterior hippocampus showed a different pattern over time: the initial increase in gray matter during the learning period was even more pronounced toward the third time point. These results indicate that the acquisition of a great amount of highly abstract information may be related to a particular pattern of structural gray matter changes in particular brain areas.

Adult↗
PubMed1995

In vivo evidence of structural brain asymmetry in musicians.

Certain human talents, such as musical ability, have been associated with left-right differences in brain structure and function. In vivo magnetic resonance morphometry of the brain in musicians was used to measure the anatomical asymmetry of the planum temporale, a brain area containing auditory association cortex and previously shown to be a marker of structural and functional asymmetry. Musicians with perfect pitch revealed stronger leftward planum temporale asymmetry than nonmusicians or musicians without perfect pitch. The results indicate that outstanding musical ability is associated with increased leftward asymmetry of cortex subserving music-related functions.

Adult↗
PubMed2003

Computer-assisted imaging to assess brain structure in healthy and diseased brains.

Neuroanatomical structures may be profoundly or subtly affected by the interplay of genetic and environmental factors, age, and disease. Such effects are particularly true in healthy ageing individuals and in those who have neurodegenerative diseases. The ability to use imaging to identify structural brain changes associated with different neurodegenerative disease states would be useful for diagnosis and treatment. However, early in the progression of such diseases, neuroanatomical changes may be too mild, diffuse, or topologically complex to be detected by simple visual inspection or manually traced measurements of regions of interest. Computerised methods are being developed that can capture the extraordinary morphological variability of the human brain. These methods use mathematical models sensitive to subtle changes in the size, position, shape, and tissue characteristics of brain structures affected by neurodegenerative diseases. Neuroanatomical features can be compared within and between groups of individuals, taking into account age, sex, genetic background, and disease state, to assess the structural basis of normality and disease. In this review, we describe the strengths and limitations of algorithms of existing computer-assisted tools at the most advanced stage of development, together with available and foreseeable evidence of their usefulness at the clinical and research level.

Algorithms↗
PubMedDate not supplied

Structural brain abnormalities in adult males with clefts of the lip and/or palate.

PURPOSE: To evaluate brain morphology of adult males with nonsyndromic clefts of the lip and/or palate (NSCLP) in comparison to a matched healthy control group. METHODS: Brain structure was measured using quantitative analysis of magnetic resonance images. RESULTS: Subjects with NSCLP had significant abnormalities in brain morphology consisting of abnormally enlarged anterior regions of the cerebrum, and decreased volumes of the posterior cerebrum and cerebellum. Overall, the most severely affected region was the left temporal lobe. Furthermore, these structural abnormalities were directly related to cognitive dysfunction. CONCLUSIONS: These findings highlight the important relationship and interplay between face and brain development.

Abnormalities, Multiple↗
PubMed1994

Event-related potential abnormalities correlate with structural brain alterations and clinical features in patients with chronic schizophrenia.

Patients with schizophrenia appear to have abnormalities in both brain structures and information processing. Several recent reports have suggested that correlations exist between such measures. We examined the volume of several brain regions using magnetic resonance imaging (MRI), and also assessed both information processing, using brain event-related potentials (ERPs), and clinical symptomatology in sixteen medicated patients with schizophrenia. Subjects were tested using auditory and visual discrimination tasks. From the ERPs elicited by stimuli presented with relative probabilities of 0.1, the N100, N200, and P300 components were identified and measured. All subjects also had MRI scans that included 12 contiguous coronal sections, each 1 cm thick. From these scans, the following structures were identified and the volume or area quantified: third ventricle, lateral ventricles (partial), amygdala and hippocampus (one slice), partial brain volume (in one slice through the parietal lobe), and total prefrontal and temporal lobe gray and white matter in both cortical regions. Significant correlations were found between hippocampal area and the amplitude of the auditory and visual N200, and between the right hippocampus and the visual P300. Lower but significant correlations were seen between auditory P300 and measures of left temporal lobe structures. Auditory P300 amplitude correlated inversely with positive symptoms of schizophrenia. These preliminary results suggest that the ERP abnormalities in patients with schizophrenia are associated with temporal lobe pathology.

Adult↗
PubMed1992

Structural brain imaging abnormalities associated with schizophrenia and partial trisomy of chromosome 5.

Chromosomal abnormalities occurring in association with mental illness provide a unique opportunity to study the interaction of genetic abnormalities and the brain in mental illness. Four individuals from a family in which schizophrenia was found to cosegregate with a partial trisomy of chromosome 5 were studied with computed tomography and magnetic resonance imaging. Temporal lobe atrophy was found in the two trisomic males and in the asymptomatic balanced translocation female. In addition, a large cavum septum pellucidum and a cavum vergae were found in the older trisomic individual. Scans from the normal male were free of abnormalities. These results suggest that molecular studies of the translocation breakpoints in this chromosomal abnormality may be of interest, and encourage further studies of brain structure in other chromosomal abnormalities associated with psychosis.

Adult↗
PubMed1996

Structural brain imaging in biological psychiatry.

The application of X-ray CT and magnetic resonance imaging to the study of brain structure in psychiatry research is reviewed. In schizophrenia, CT showed minor enlargements of fluid spaces; MR has shown volume reductions in medial temporal lobe structures and, most recently, general cortical grey matter. In affective disorders, subcortical white matter lesions seem to characterise particular subgroups. In childhood autism, no clear consensus has emerged despite earlier claims for cerebellar pathology. In dementia, medial temporal changes can be detected reliably in Alzheimer's disease and are of diagnostic and prognostic importance.

Brain↗
PubMed2006

Structural brain abnormalities in the frontostriatal system and cerebellum in pedophilia.

Even though previous neuropsychological studies and clinical case reports have suggested an association between pedophilia and frontocortical dysfunction, our knowledge about the neurobiological mechanisms underlying pedophilia is still fragmentary. Specifically, the brain morphology of such disorders has not yet been investigated using MR imaging techniques. Whole brain structural T1-weighted MR images from 18 pedophile patients (9 attracted to males, 9 attracted to females) and 24 healthy age-matched control subjects (12 hetero- and 12 homosexual) from a comparable socioeconomic stratum were processed by using optimized automated voxel-based morphometry within multiple linear regression analyses. Compared to the homosexual and heterosexual control subjects, pedophiles showed decreased gray matter volume in the ventral striatum (also extending into the nucl. accumbens), the orbitofrontal cortex and the cerebellum. These observations further indicate an association between frontostriatal morphometric abnormalities and pedophilia. In this respect these findings may support the hypothesis that there is a shared etiopathological mechanism in all obsessive-compulsive spectrum disorders.

Adult↗
PubMed1988

Structural brain correlates of anterograde memory deficits in multiple sclerosis.

Progressive decline of anterograde memory functions has been increasingly recognized as a frequent symptom in chronic multiple sclerosis. In order to investigate the brain structures involved, magnetic resonance imaging was performed in 20 patients. Neuropsychological assessment included the WAIS and WMS subtests information, picture completion, similarities, digit span, logical memory, and paired associate learning. All patients with severely impaired memory functions (n = 5) showed bilateral lesions in the medial temporal lobe, whereas in those patients with moderate (n = 10) or no measurable impairment of memory testing (n = 5) either no lesions were seen in the medial temporal lobes or these lesions were restricted to one side. A post hoc cluster analysis strikingly confirmed these results. The differences could not be related to the age of the patients, the disease duration, or the level of education. Extensive lesions in the white matter of the frontal lobes, thinning and lining of the corpus callosum, and bilateral involvement of the anterior cingulate gyrus had no bearing on the neuropsychological results. These findings indicate that bilateral demyelination in the hippocampal regions is the most likely explanation for the impairment of anterograde memory in such patients.

Adult↗
PubMed2002

Structural brain differences between never-treated patients with schizophrenia, with and without dyskinesia, and normal control subjects: a magnetic resonance imaging study.

BACKGROUND: In south India, abnormal movements indistinguishable from tardive dyskinesia have been observed in chronically ill patients with schizophrenia who have never received antipsychotic medication. The present study, using magnetic resonance imaging, examines brain structure in such patients, in those without dyskinesia, and in normal control subjects. METHODS: Chronically ill patients with schizophrenia with and without dyskinesia and controls were identified in villages south of Chennai, India (each group, n = 31). Patients' mental state was assessed by the Positive and Negative Syndrome Scale for schizophrenia, dyskinesia by the Abnormal Involuntary Movements Scale, and parkinsonism by the Simpson and Angus scale. In patients and controls, magnetic resonance imaging measured the volume of the caudate and lentiform nuclei and the lateral ventricle-hemisphere ratio. RESULTS: The left lentiform nucleus was significantly (11%) larger in patients with dyskinesia compared with controls, and the right lateral ventricle-hemisphere ratio was significantly (33%) larger in patients without dyskinesia compared with controls. In all 3 groups, there were significant positive correlations between age and ventricle-hemisphere ratio. In controls, but not in patients, there were significant negative correlations between age and the volume of the caudate and lentiform nuclei. CONCLUSIONS: Never-treated patients with dyskinesia may have striatal pathologic conditions and may represent a subgroup of patients with schizophrenia; in those without abnormal movements, cortical atrophy is more apparent. The schizophrenic process may interfere with normal age-related anatomical changes in the basal ganglia.

Adolescent↗
PubMed2001

Volumes of brain structures in twins discordant for schizophrenia.

BACKGROUND: The study was designed to examine the relative contributions of genetic and nongenetic factors to structural brain abnormalities in schizophrenia and subjects at risk to develop the disorder. METHODS: The brains of 15 monozygotic and 14 same-sex dizygotic twins discordant for schizophrenia (patients) and 29 healthy twins pair-wise matched for zygosity, sex, age, and birth order were studied using high-resolution magnetic resonance imaging scans. RESULTS: Intracranial and whole-brain corrected frontal lobe volumes were smaller (4.6% and 2.7%, respectively) in discordant monozygotic twins as compared with healthy monozygotic twins. Irrespective of zygosity, discordant twins had smaller whole-brain (2%), parahippocampal (9%), and hippocampal (8%) volumes than healthy twins. Moreover, patients had smaller whole-brain volumes (2. 2%) than their nonschizophrenic cotwins, who in turn had smaller brains (1%) than healthy twins. Lateral and third-ventricle volumes were increased in discordant dizygotic twins as compared with healthy dizygotic twins (60.6% and 56.6%, respectively). Finally, within discordant twins, lateral ventricles were larger (14.4%) in patients than in their nonschizophrenic cotwins. CONCLUSIONS: Smaller intracranial volumes in the monozygotic patients and their cotwins suggest that increased genetic risk to develop schizophrenia is related to reduced brain growth early in life. The additional reduction in whole-brain volume found in the patients suggests that the manifestation of the disorder is related to (neurodegenerative) processes that are most likely nongenetic in origin.

Adult↗
PubMed2002

Giant congenital melanocytic nevi in a patient with brain structural malformations and multiple lipomatosis.

We present a 9-year-old boy diagnosed from birth with giant congenital melanocytic nevi. He had central structural brain malformations of hemimegalencephaly of the right frontotemporal lobe and left occipitoparietal lobe, choroid plexus hypertrophy, and a Dandy-Walker variant. In addition, he developed multiple lipomatoses. These lesions were cutaneous except for two at the cerebellopontine angles, which were present from birth. This patient represents a rarely documented example of two histopathologies resulting in serious complications. The diagnostic issues and histopathologic process are discussed.

Brain↗
PubMed2002

Brain structure and cognition in a community sample of elderly Latinos.

BACKGROUND: Previous studies have found that hippocampal atrophy and white matter hyperintensities (WMH) on MRI are linked to cognitive impairment and dementia. The authors measured these variables in a population-based cohort of older Mexican Americans with a wide spectrum of cognitive ability, ranging from normal cognition to dementia. OBJECTIVE: To investigate whether these structural brain changes were seen in individuals prior to the development of dementia and how these changes were related to the presence of dementia. METHODS: A sample of 122 subjects was selected from the Sacramento Area Latino Study on Aging, and subjects were categorized into four groups of increasing levels of cognitive impairment: normal, memory impaired (MI), cognitively impaired but not demented (CIND), and demented. Hippocampal volume was quantified using a region of interest approach. WMH was rated on a semiquantitative scale as the percent of total volume of white matter. RESULTS: Hippocampal volume was significantly reduced in CIND and demented individuals, and WMH were significantly increased in demented subjects. MI subjects did not have any significant changes in hippocampal volume or WMH. The risk for developing dementia was significantly and comparably increased in subjects with either hippocampal atrophy or high WMH. However, the risk for dementia increased dramatically in subjects with both hippocampal atrophy and a high degree of WMH. CONCLUSION: Reductions in hippocampal volume may be present before dementia but not until cognitive impairment is relatively severe. Because there is a synergistic effect between high WMH and hippocampal atrophy, interactions between vascular and degenerative processes may be important determinants of dementia.

Aged↗
PubMed2002

Mapping genetic influences on human brain structure.

Recent advances in brain imaging and genetics have empowered the mapping of genetic and environmental influences on the human brain. These techniques shed light on the 'nature/nurture' debate, revealing how genes determine individual differences in intelligence quotient (IQ) or risk for disease. They visualize which aspects of brain structure and function are heritable, and to what degree, linking these features with behavioral or cognitive traits or disease phenotypes. In genetically transmitted disorders such as schizophrenia, patterns of brain structure can be associated with increased disease liability, and sites can be mapped where non-genetic triggers may initiate disease. We recently developed a large-scale computational brain atlas, including data components from the Finnish Twin registry, to store information on individual variations in brain structure and their heritability. Algorithms from random field theory, anatomical modeling, and population genetics were combined to detect a genetic continuum in which brain structure is heavily genetically determined in some areas but not others. These algorithmic advances motivate studies of disease in which the normative atlas acts as a quantitative reference for the heritability of structural differences and deficits in patient populations. The resulting genetic brain maps isolate biological markers for inherited traits and disease susceptibility, which may serve as targets for genetic linkage and association studies. Computational methods from brain imaging and genetics can be fruitfully merged, to shed light on the inheritance of personality differences and behavioral traits, and the genetic transmission of diseases that affect the human brain.

Algorithms↗
PubMed1994

Structural brain abnormalities as indicators of vulnerability to schizophrenia.

The literature on structural brain abnormalities in schizophrenia is examined to determine whether these abnormalities represent viable candidate markers of vulnerability to the disorder. A majority of studies agree in finding that schizophrenia patients as a group have significantly larger ventricles and smaller limbic brain structures than normal control subjects, but about 50 percent of patients fall within the range of control subjects on these measures. This result has been interpreted to suggest that structural abnormalities characterize only a subgroup of patients. However, given the substantial degree of normal variability in brain structure between families, the use of biologically unrelated individuals as controls is misleading. Studies that have compared schizophrenia patients with their unaffected first-degree relatives have found a much higher sensitivity rate for ventricular enlargement and reduced limbic volumes (i.e., 70%-100%). This high within-family sensitivity, together with evidence from meta-analytic reviews of a substantial relationship between ventricular enlargement and severity of illness, argues in favor of a continuous distribution of the brain pathology in schizophrenia and against a model in which the pathology characterizes only a subgroup of patients. The structural abnormalities observed in both younger and older patients have been found to be highly correlated with familial risk for schizophrenia and obstetric complications, suggesting that some part of the deviance may be present in the premorbid state and that it may reflect both genetic and environmental etiologic processes. The evidence for specificity of the deficits to schizophrenia is equivocal, but no study has yet compared the within-family sensitivities of morphological measures among the major psychiatric conditions. Additional studies using first-degree relatives and well-defined neuroanatomical measurements are needed to determine which brain regions have the highest sensitivities as indicators of schizophrenia in families.

Brain↗
PubMed2002

Cognitive and physiologic correlates of subclinical structural brain disease in elderly healthy control subjects.

CONTEXT: Healthy elderly persons commonly show 4 types of change in brain structure-cortical atrophy, central atrophy, deep white-matter hyperintensities, and periventricular hyperintensities-as forms of subclinical structural brain disease (SSBD). OBJECTIVES: To characterize the volumes of SSBD present with aging and to determine the associations of SSBD, physiology, and cognitive function. DESIGN: Cross-sectional study. SETTING: University of California, Los Angeles, Neuropsychiatric Institute. SUBJECTS: Forty-three community-dwelling healthy control subjects, aged 60 through 93 years. MAIN OUTCOME MEASURES: Volumetric magnetic resonance imaging, neuropsychological testing, and quantitative electroencephalographic coherence (functional connectivity) between brain regions. RESULTS: Regression models demonstrated significant relationships between SSBD volumes, age, cognitive performance, and connectivity. Cortical and central atrophy and periventricular hyperintensities had significant associations with age while deep white-matter hyperintensities did not. Posterior atrophy showed stronger associations with age than did anterior atrophy. Only a subset of subjects at older ages showed large SSBD volumes; older subjects primarily showed increasing variance of SSBD. Although all subjects scored within the normal range on cognitive testing, SSBD volume was inversely related to performance, most notably on the Trail-Making Test part B and the Shipley-Hartford Abstract Reasoning test. Coherence had significant associations with SSBD. Path analysis supported mediation of the effects of deep white-matter hyperintensities and periventricular hyperintensities on cognition by altered connectivity. For several measures, cognitive performance was best explained by coherence, and only secondarily by SSBD. CONCLUSIONS: Modest volumes of SSBD were associated with decrements in cognitive performance within the normal range in healthy subjects. Lower coherence was associated with greater volumes of SSBD and increasing age. Path analysis models suggest that brain functional connectivity mediates some effects of SSBD on cognition.

Aged↗