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Results for “Brain Mapping”

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At least 649 records · Page 36Linked to original sources

PubMed1999

The human cadherin-10 gene: complete coding sequence, predominant expression in the brain, and mapping on chromosome 5p13-14.

In a quest for novel cadherin gene family members in the human dbEST database, an interesting EST clone was identified and chosen for subsequent analysis. Using the technique of 5' rapid amplification of cDNA ends, we isolated the complete coding sequence and a large part of the UTRs of a novel gene. The sequence appeared to correspond to the human cadherin-10 gene, whose sequence was only partially known before. The expression pattern of this cadherin was found to be largely brain-specific, with additional expression in both adult and fetal kidney, and with minor expression in prostate and fetal lung. By FISH analysis the genomic location was determined at human chromosome 5p13-14, which is nearby the reported positions of the human cadherin-6, -12, and cadherin-14 (CDH18) genes. Cadherin-10 shows high relationship to the human cadherin-6 gene.

Adult↗

PubMed1999

Functional MRI in children with epilepsy.

Advances in brain mapping with functional magnetic resonance imaging (fMRI) have opened an important window into understanding how language is organized in the developing brain. Children with epilepsy, particularly those anticipating surgical intervention, may benefit from preoperative language localization with fMRI, thus minimizing the risk of incurring new deficits. Clinical applications of fMRI, however, await more information on how different linguistic skills are represented in the developing brain and how epileptic lesions impact on this organization at different stages of cognitive development. This article presents some of the current methods for brain mapping in children as well as early results using fMRI for language mapping in pediatric epilepsy.

Child Development↗

PubMed2000

Automatic labelling of the human cortical surface using sulcal basins.

Human brain mapping aims at establishing correspondences between brain function and brain anatomy. One of the most intriguing problems in this field is the high interpersonal variability of human neuroanatomy which makes studies across many subjects very difficult. The cortical folds ('sulci') often serve as landmarks that help to establish correspondences between subjects. In this paper, we will present a method that automatically detects and attributes neuroanatomical names to the cortical folds using image analysis methods applied to magnetic resonance data of human brains. We claim that the cortical folds can be subdivided into a number of substructures which we call sulcal basins. The concept of sulcal basins allows us to establish a complete parcellation of the cortical surface into separate regions. These regions are neuroanatomically meaningful and can be identified from MR data sets across many subjects. Sulcal basins are segmented using a region growing approach. The automatic labelling is achieved by a model matching technique.

Algorithms↗

PubMed2000

Trilinear modeling of event-related potentials.

This paper describes a method for estimating a set of spatial components (brain maps) and temporal components (waveforms) of brain potentials. These components play the role of bases of a coordinate system, in the sense that the brain potentials of any subject can be represented as superpositions of these components. The representation is unique given the spatial and temporal components, and this decomposition is particularly appealing for comparing the brain potentials of different subjects (say alcoholics and controls). It can also be used for single trial modeling, clinical classification of patients, and data filtering. The method is based on the topographic component model (TCM, Möcks 1988) which models brain potentials in a trilinear form. We extend the TCM in two aspects. First, the diagonal amplitude matrix is replaced by a general loading matrix based on some neurophysiological considerations. Secondly, the number of spatial components and the number of temporal components can be different. The spatial components and temporal components are obtained respectively by performing singular value decomposition (SVD). This method is illustrated with visual P3 data.

Alcoholism↗

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↗

PubMed2003

Mixed dishomogeneous hemorrhagic brain contusions. Mapping of cerebral blood flow.

The aim of the study was to verify whether regional cerebral blood flow (rCBF) was distributed centrifugally in traumatic hemorrhagic contusions with multiple cores within an oedematous area. Seventeen traumatic brain contusions, from 14 patients with severe head injury (GCS < 9), were analyzed during 39 Xenon-enhanced computerized tomography (Xe-CT) studies. The CBF was measured in 3 concentric regions of interest (ROls): the hemorrhagic core, the intracontusional oedematous low density area and a 1 cm rim of pericontusional normal-appearing brain tissue surrounding the contusion. Differences between rCBFs in the three ROIs were found (p < 0.0001). rCBF in both the hemorrhagic core (21.4 +/- 19.4 ml/ 100gr/min) and the intracontusional low density area (28.4 +/- 19 ml/100gr/min) were lower than rCBF in pericontusional normal-appearing area (41.9 +/- 16 ml/100gr/min) (p < 0.0001). No significant differences were found between rCBF measured in the hemorrhagic core and intracontusional low density area (p = 0.184). Our study suggests that in the mixed density contusions with multiple hemorrhagic cores, the CBF is concentrically distributed, improving from the core to the periphery.

Adult↗

PubMed2005

Proteomic mapping of brain plasma membrane proteins.

Proteomics is potentially a powerful technology for elucidating brain function and neurodegenerative diseases. So far, the brain proteome has generally been analyzed by two-dimensional gel electrophoresis, which usually leads to the complete absence of membrane proteins. We describe a proteomic approach for profiling of plasma membrane proteins from mouse brain. The procedure consists of a novel method for extraction and fractionation of membranes, on-membrane digestion, diagonal separation of peptides, and high-sensitivity analysis by advanced MS. Breaking with the classical plasma membrane fractionation approach, membranes are isolated without cell compartment isolation, by stepwise depletion of nonmembrane molecules from entire tissue homogenate by high-salt, carbonate, and urea washes followed by treatment of the membranes with sublytic concentrations of digitonin. Plasma membrane is further enriched by of density gradient fractionation and protein digested on-membrane by endoproteinase Lys-C. Released peptides are separated, fractions digested by trypsin, and analyzed by LC-MS/MS. In single experiments, the developed technology enabled identification of 862 proteins from 150 mg of mouse brain cortex. Further development and miniaturization allowed analysis of 15 mg of hippocampus, revealing 1,685 proteins. More that 60% of the identified proteins are membrane proteins, including several classes of ion channels and neurotransmitter receptors. Our work now allows in-depth study of brain membrane proteomes, such as of mouse models of neurological disease.

Animals↗

PubMed2001

Mapping dissociations in verb morphology.

Substantial behavioural and neuropsychological evidence has been amassed to support the dual-route model of morphological processing, which distinguishes between a rule-based system for regular items (walk-walked, call-called) and an associative system for the irregular items (go-went). Some neural-network models attempt to explain the neuropsychological and brain-mapping dissociations in terms of single-system associative processing. We show that there are problems in the accounts of homogeneous networks in the light of recent brain-mapping evidence of systematic double-dissociation. We also examine the superior capabilities of more internally differentiated connectionist models, which, under certain conditions, display systematic double-dissociations. It appears that the more differentiation models show, the more easily they account for dissociation patterns, yet without implementing symbolic computations.

Journal Article↗

PubMed2001

Action sites of adrenomedullin in the rat brain: functional mapping by Fos expression.

The effects of intracerebroventricular (icv) administration of adrenomedullin (AM) and proadrenomedullin NH2-terminal 20 peptide (PAMP) on the expression of Fos in the central nervous system (CNS) were examined in conscious rats, using immunohistochemistry. Fos-like immunoreactivity (LI) was detected in various brain areas of the rats, including the supraoptic nucleus, the paraventricular nucleus, the locus coeruleus, the area postrema and the nucleus of the tractus solitarius 90 min after icv administration of AM. Few cells with Fos-LI were found in the CNS 90 min after icv administration of saline. Fos-LI was also detected in the various hypothalamic areas after icv administration of PAMP. These results suggest that centrally administered AM and PAMP may cause physiological responses through the activation of a neural network in the hypothalamus and the brainstem.

Adrenomedullin↗

PubMedDate not supplied

Forthergillian Lecture. Imaging human brain function.

The non-invasive brain scanning techniques introduced a quarter of a century ago have become crucial for diagnosis in clinical neurology. They have also been used to investigate brain function and have provided information about normal activity and pathogenesis. They have been used to investigate functional specialization in the brain and how specialized areas communicate to generate complex integrated functions such as speech, memory, the emotions and so on. The phenomenon of brain plasticity is poorly understood and yet clinical neurologists are aware, from everyday observations, that spontaneous recovery from brain lesions is common. An improved understanding of the mechanisms of recovery may generate new therapeutic strategies and indicate ways of modulating mechanisms that promote plastic compensation for loss of function. The main methods used to investigate these issues are positron emission tomography and magnetic resonance imaging (M.R.I.). M.R.I. is also used to map brain structure. The techniques of functional brain mapping and computational morphometrics depend on high performance scanners and a validated set of analytic statistical procedures that generate reproducible data and meaningful inferences from brain scanning data. The motor system presents a good paradigm to illustrate advances made by scanning towards an understanding of plasticity at the level of brain areas. The normal motor system is organized in a nested hierarchy. Recovery from paralysis caused by internal capsule strokes involves functional reorganization manifesting itself as changed patterns of activity in the component brain areas of the normal motor system. The pattern of plastic modification depends in part on patterns of residual or disturbed connectivity after brain injury. Therapeutic manipulations in patients with Parkinson's disease using deep brain stimulation, dopaminergic agents or fetal mesencephalic transplantation provide a means to examine mechanisms underpinning plastic change. Other models of plastic change, such as normal visuospatial learning or re-establishing speech comprehension after cochlear implantation in the deaf illustrate how patterns of brain function adapt over time. Limitations of the scanning techniques and prospects for the future are discussed in relation to new developments in the neuroimaging field.

Brain↗

PubMed2005

Intraoperative functional MRI: implementation and preliminary experience.

For a non-invasive identification of eloquent brain areas in neurosurgical procedures up to now only preoperative functional brain mapping techniques are available. These are based, e.g., on preoperative functional magnetic resonance imaging (fMRI) investigations in awake patients. The aim of this study was to investigate the feasibility to perform fMRI during neurosurgical procedures in anesthetized patients. For that purpose, a passive stimulation paradigm with peripheral nerve stimulation was applied. A 1.5-T MR scanner placed in a radiofrequency-shielded operating room with an adapted operating table was used for intraoperative fMRI. The fMRI data were analyzed during acquisition by an online statistical evaluation package installed on the MR scanner console. In addition, phase reversal of somatosensory evoked potentials was used for verification of intraoperative fMRI. In four anesthetized patients with lesions in the vicinity of the central region a total of 11 fMRI measurements were successfully acquired and analyzed online. Activation was found in the somatosensory cortex, which could be confirmed by intraoperative phase reversal for each measurement. Furthermore, statistical parametric mapping (SPM) was employed for an extensive offline data analysis. We did not observe any neurological deterioration or complications due to the stimulation technique. Intraoperative fMRI is technically feasible allowing a real-time identification of eloquent brain areas despite brain shift.

Adult↗

PubMed1998

Localization of language-related cortex with 15O-labeled water PET in patients with gliomas.

Measurement of relative cerebral blood flow (CBF) with 15O-labeled water PET has been widely used for brain mapping experiments on language functions in normal volunteers and patients with epilepsy. We focused on the question of whether PET during speech activation is an appropriate method for noninvasive determination of language-related cortex in patients with brain tumors. Furthermore, the suitability of the method for determination of hemispheric language dominance was examined and compared to the results of the Edinburgh Handedness Inventory. Ten right-handed and six left-handed patients with gliomas were examined prior to surgery while repeatedly performing word repetition and verb generation tasks. A set of volumes of interest (VOIs) was drawn on coregistered MRI in order to account for anatomic variability as well as anatomical alterations due to tumor mass effect. Repetition of nouns did not produce significant hemispheric differences. During stimulation by verb generation, reliable lateralized activations of Broca's area and supplementary motor area were detected in all right-handed patients. Of the left-handed patients, two showed clear right lateralization, two activated Broca's area bilaterally, and two had a pattern similar to that of right-handers. Patients with bilateral activations showed the strongest tendency toward bihandedness according to the handedness inventory. Lateralization of supplementary motor area in left-handers corresponded to lateralized activity in Broca's area. Tumors in the vicinity of language-related regions did not alter activation responses. In conclusion, measurement of CBF changes during verb generation permits identification of language-related areas in patients with gliomas with strong lateralization related to hemispheric dominance. These findings may be of particular clinical interest for left-handed patients.

Adult↗

PubMed1998

Spectral analysis of electroencephalography changes after choking in judo (juji-jime).

PURPOSE: The present study was carried out to investigate possible electroencephalographic changes induced by choking in judo (shime-waza) by means of spectral analysis and brain mapping. METHODS: Power spectral changes in Electroencephalography (EEG) were recorded in six experienced judoka who underwent a choking trial with a "shime-waza choking" technique called juji-jime. RESULTS: A significant increase of global field power in the delta- and theta-range occurred, while physiological alpha-power decreased. These changes in the low-frequency range reached a statistically significant level within a time span up to 20 s after choking, which was performed at an average choking time of 8 s. In no case did choking provoke neuropsychological symptoms. Yet, spectral EEG-analysis revealed subclinical changes of brain function. CONCLUSIONS: Choking in judo may induce subclinical electroencephalographic perturbations. The extent and duration can be objectified by means of spectral analysis of EEG data, global field power computation, and brain-mapping representation.

Airway Obstruction↗

PubMed1993

Minimally invasive brain surgery.

Minimally invasive brain surgery refers to technological advances refining surgical access that have enabled neurosurgeons to reduce the morbidity and improve the accuracy and quality of neurosurgical procedures. These advances include computer-assisted stereotaxis, intraoperative ultrasound, brain mapping and neuroendoscopy. Computer-assisted stereotaxis includes not only smaller and accurate craniotomies but precision radiotherapy with radiosurgery and interstitial brachytherapy.

Brain Diseases↗

PubMed2004

Psychostimulant alters expression of DNA methyltransferase mRNA in the rat brain.

Methamphetamine (MAP), the most frequently abused substance in Japan, causes severe drug dependence and psychosis, similar to schizophrenia. It is suggested that long-term alterations in gene expression is related to MAP-induced brain dysfunction, including dependence and psychosis. DNA (cytosine-5) methyltransferase (Dnmt), a methylating enzyme of cytosine residues on CpG-dinucleotides, plays an important role in X chromosome inactivation, genomic imprinting, and gene expression. Reelin is an extracellular matrix protein secreted by GABAergic interneurons. Heterozygous reeler mice that exhibit a 50% downregulation of reelin expression replicate the dendritic spine and GABAergic defects described in schizophrenia. DNA methylation plays an important role in the epigenetic modification of reelin expression. We previously found that MAP could alter expression of Dnmt1 mRNA in the rat brain. In this study, we examined the brain mRNA for Dnmt2 and reelin in MAP-treated Wistar rats. Acute MAP (4 mg/kg) treatment significantly decreased Dnmt2 mRNA by 27% to 39% in hippocampus dentate gyrus, CA1, and CA3 24 h after treatment, and significantly decreased reelin mRNA by 28% in frontal cortex 3 h after treatment. These results suggest that (1) MAP can alter DNA methylation as well as expression of genes in these brain regions, and (2) decrease in reelin mRNA in the frontal cortex is similar to heterozygous reeler mice, which might be related to schizophrenia-like psychotic symptoms of MAP psychosis.

Animals↗

PubMed1999

Imaging strategies in depression.

Functional brain imaging in depressive disorder aims to map brain areas associated with depressive illness or to define the neurochemical correlates of the illness and its treatment. Regional deficits of functional (neural) activity has been consistently detected in the brains of subjects with ongoing affective symptoms, particularly in prefrontal areas. Understanding how these prefrontal deficits can be related to neuroanatomical circuitry, neurochemistry and normal cognitive functions is the major challenge in taking these findings forward. Although many neurochemical systems remain to be adequately imaged in vivo, significant progress has been made in the development of relevant radiotracers, particularly for select serotonin and dopamine receptor subtypes. For the future, functional brain imaging of the neurochemistry associated with core symptoms and treatment responses will be necessary for an adequate description of the pathophysiology of depressive illness.

Animals↗

PubMed2002

Neuronavigation: concept, techniques and applications.

Neuronavigation provides intraoperative orientation to the surgeon, helps in planning a precise surgical approach to the targetted lesion and defines the surrounding neurovascular structures. Incorporation of the functional data provided by functional MRI and magnetoencephalography (MEG) with neuronavigation helps to avoid the eloquent areas of the brain during surgery. An intraoperative MRI enables radical resection of the lesions, the possibility of immediate control for tumor remnants and updates of neuronavigation with intraoperative images to compensate for brain shift. In this study, the experience of 432 patients undergoing neuronavigation assisted neurosurgical interventions using either the pointer-based or microscope-based navigational systems at the University of Erlangen-Nuremberg, Germany is presented. The procedures included stereotactic biopsy (n=53), stereotactic cyst puncture/ventricular drainage (n=15), eloquent cortex/tumor localization to facilitate tumor resection, assessment of neurovascular structures in the vicinity of tumors of the sellar-suprasellar regions, skull base, posterior fossa and ventricular region (n=252), and, surgery for epilepsy (n=9). Functional brain mapping using fMRI and MEG and their integration with neuronavigation was carried out in 24 and 128 patients respectively. The simultaneous use of intraoperative MRI to look for the remaining tumor was done in 159 patients and the update of navigational data was carried out in 17 patients. The mean system accuracy obtained by using both the fiducial registration as well as anatomical landmark-surface fitting computer algorithm was 1.81 mm. This study reviews the relative merits and demerits of the pointer and microscope based navigational systems and also highlights the role of functional brain mapping and intraoperative MRI, when integrated with neuronavigation, in the surgical decision-making to offer the chances of more radical resections with minimal morbidity.

Adolescent↗

PubMed2001

Multimodality neuroimaging: research and clinical applications.

This manuscript reviews the current stance and the pertinent problems of transcranial magnetic stimulation (TMS) and functional magnetic resonance imaging (fMRI) as brain mapping methodologies. The missing structure-function relation limits the use of TMS, whereas the uncertainty about the functional significance of activated cortical regions might render interpretation of fMRI studies difficult. Advances in image processing, however, allowed for 3- dimensional real-time visual guidance of TMS and integration with fMRI data. We describe the method used to coregister TMS and fMRI and present examples where a multimodality neuroimaging approach might add to our understanding of normal and pathological brain function.

Brain Mapping↗