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Results for “Brain Mapping”

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PubMed2004

Topodiagnostic investigations on the sympathoexcitatory brain stem pathway using a new method of three dimensional brain stem mapping.

OBJECTIVES: To study the incompletely understood sympathoexcitatory pathway through the human brain stem, using a new method of three dimensional brain stem mapping on the basis of digitally postprocessed magnetic resonance imaging (MRI). METHODS: 258 consecutive patients presenting with acute signs of brain stem ischaemia underwent biplane T2 and EPI diffusion weighted MRI, with slice orientation parallel and perpendicular to a transversal slice selection of the stereotactic anatomical atlas of Schaltenbrand and Wahren, 1977. The individual slices were digitally normalised and projected onto the appropriate slices of the anatomical atlas. For correlation analysis lesions were imported into a three dimensional model of the human brain stem. RESULTS: 31 of the 258 patients had Horner's syndrome caused by acute brain stem ischaemia. Only four of the patients with Horner's syndrome had pontine infarctions, 12 had pontomedullary lesions, and 15 had medullary lesions. Correlation analysis showed significantly affected voxels in the dorsolateral medulla but not in the pons. A statistical comparison with infarct topology in patients with medullary lesions but without Horner's syndrome indicated that involvement of the medial and ventral part of affected voxels located in the ventrolateral medullary tegmentum was specific for Horner's syndrome. CONCLUSIONS: Based on this first in vivo topodiagnostic study, the central sympathoexcitatory pathway probably descends through the dorsal pons before converging on specific generators in the ventrolateral medullary tegmentum at a level below the IX and X nerve exits.

Aged↗

PubMed1996

Whole-brain functional mapping with isotropic MR imaging.

PURPOSE: To assess the reliability and sensitivity of gradient-echo, isotropic multisection echo-planar magnetic resonance (MR) imaging for within-subject whole-brain mapping. MATERIALS AND METHODS: Eight right-handed healthy volunteers underwent gradient-echo, echo-planar MR imaging while they performed a motor task on three occasions over 2-3 months. Ninety-six whole-brain volumes were acquired in 8 minutes 48 seconds. A rigorous statistical threshold for determining activation was set at P < .05 and was Bonferroni corrected for approximately 15,000 cortical voxels. RESULTS: In all subjects, reproducible activation was demonstrated in multiple cortical areas and in the cerebellum specific to the motor system. Of the activated voxels, 75%-78% were confined to the motor areas during all sessions. No statistically significant difference was found in the proportion of activated voxels in any motor region (relative to the total number of activated voxels in the whole brain) across the three sessions. The centers of mass of the activated areas were within 2.5 resolution elements of the image across the three sessions. CONCLUSION: Isotropic multisection echo-planar MR imaging, has the potential for noninvasive, reliable within-subject mapping of whole-brain functional anatomy.

Adult↗

PubMed1986

Motor responses measured by brain electrical activity mapping.

The brain electrical activity of right-handed normal subjects was studied while they were exposed to motor performance tasks that were of increasing difficulty. Each task lasted 45-60 s, and a 30-s period of each task was analyzed by a spectrum analyzer. Data are presented in topographic maps showing the electrical activity for each task, in delta (1-4 cycles [c]/s), alpha (8-12 c/s), and beta 2 (18-24 c/s). The results showed a bilateral decrease in amplitude in sensorimotor areas relative to baseline, for a single hand movement. Tasks that required the programming of movement showed baseline/task differences in amplitude in additional areas; the right frontal area, the prefrontal area, the posterior parietal area, and the left temporal area. The results obtained suggest that different topographical areas are involved in motor tasks that require increased level of programming.

Brain Mapping↗

PubMed1992

Magnetic resonance imaging mapping of brain function. Human visual cortex.

Magnetic resonance imaging (MRI) studies of human brain activity are described. Task-induced changes in brain cognitive state were measured using high-speed MRI techniques sensitive to changes in cerebral blood volume (CBV), blood flow (CBF), and blood oxygenation. These techniques were used to generate the first functional MRI maps of human task activation, by using a visual stimulus paradigm. The methodology of MRI brain mapping and results from the investigation of the functional organization and frequency response of human primary visual cortex (V1) are presented.

Brain Mapping↗

PubMed2006

The role of magnetoencephalography in pediatric epilepsy surgery.

INTRODUCTION: Magnetoencephalography (MEG) is a new diagnostic imaging and brain mapping device that has been recently used in the context of pediatric epilepsy, epilepsy surgery, and neuronavigation. PRINCIPLES OF MAGNETOENCEPHALOGRAPHY: MEG allows for the placement of magnetic spike sources on a conventional magnetic resonance imaging scan, the so-called magnetic source imaging, so that the localization of epileptiform activity in a child can be determined. Considerable effort is placed on analyzing the configuration and number of spike waves by MEG that relate to a primary epileptiform discharge. Such MEG spike clusters are corroborated now by intraoperative invasive subdural grid monitoring that show good correlation in the majority of cases. Another important role of MEG relates to the mapping of critical regions of brain function using known paradigms for speech, motor, sensory, visual, and auditory brain cortex. FUTURE APPLICATIONS: When linked to standard neuronavigation devices, MEG brain mapping can be extremely helpful to the neurosurgeon approaching nonlesional epilepsy cases or lesional cases where the safest and most direct route to the surgical disease can be selected. As paradigms for brain mapping improve and as MEG software upgrades become more sensitive to analyzing all types of spike sources, MEG will play an increasingly important role in pediatric neurosurgery, especially for the child with intractable epilepsy.

Brain Mapping↗

PubMed2005

Full-brain T1 mapping through inversion recovery fast spin echo imaging with time-efficient slice ordering.

Brain T1 mapping has important clinical applications in detecting brain disorders. Conventional T1 mapping techniques are usually based on inversion recovery spin echo (IRSE) imaging or its more time-efficient counterpart inversion recovery fast spin echo (IRFSE) imaging because they can deliver good image quality. Multiple inversion times are required to accurately estimate T1 over a wide range of values. Without acquisition optimization, both the IRSE and the IRFSE T1 mapping techniques require long scan times to image the whole brain. To reduce the scan time and maintain the quality of the T1 maps, we propose a new full-brain T1 mapping pulse sequence based on a multislice inversion recovery fast spin echo imaging using a time-efficient slice ordering technique.

Adult↗

PubMed2006

Category-specific cortical mapping: color-naming areas.

OBJECT: It has been hypothesized that a certain degree of specialization exists within language areas, depending on some specific lexical repertories or categories. To spare hypothetical category-specific cortical areas and to gain a better understanding of their organization, the authors studied patients who had undergone electrical stimulation mapping for brain tumors and they compared an object-naming task with a category-specific task (color naming). METHODS: Thirty-six patients with no significant preoperative language deficit were prospectively studied during a 2-year period. Along with a reading task, both object- and color-naming tasks were used in brain mapping. During color naming, patients were asked to identify 11 visually presented basic colors. The modality specificity of the color-naming sites found was subsequently tested by asking patients to retrieve the color attributes of objects. High individual variability was observed in language organization among patients and in the tasks performed. Significant interferences in color naming were found in traditional language regions-that is, Broca (p < 0.003) and Wernicke centers (p = 0.05)--although some color-naming areas were occasionally situated outside of these regions. Color-naming interferences were exclusively localized in small cortical areas (< 1 cm2). Anatomical segregation of the different naming categories was apparent in 10 patients; in all, 13 color-specific naming areas (that is, sites evoking no object-naming interference) were detected in the dominant-hemisphere F3 and the supramarginal, angular, and posterior parts of the temporal gyri. Nevertheless, no specific brain region was found to be consistently involved in color naming (p > 0.05). At five sites, although visually presented color-naming tasks were impaired by stimulation, auditory color naming (for example, "What color is grass?") was performed with no difficulty, showing that modality-specific areas can be found during naming. CONCLUSIONS: Within language areas, a relative specialization of cortical language areas for color naming can be found during electrical stimulation mapping.

Adult↗

PubMedDate not supplied

Topographic mapping of brain electromagnetic signals: a review of current technology.

Topographic mapping of brain electromagnetic signals has become increasingly popular in recent years both as a clinical tool and as an area of research in its own right. The capabilities of existing computerized systems for displaying such maps and for performing localization of current sources in the brain have continued to expand. In this paper we review some of the methodological and technological issues concerning topographic mapping. These include issues of choice of interpolation algorithm, what to map, head geometry, EEG reference location, and scaling. We also discuss characteristics of clinical databases for patient comparison and the usefulness of quantitative EEG (which includes mapping) for the diagnosis of nervous system disorders. Finally, we compare five representative systems in terms of their topographic mapping capabilities. The overall conclusion is that future developments must make use of integrated data from other neuroimaging technologies such as MRI, PET, and SPECT, and determination of the normal limits of topographic parameters must be more carefully examined.

Brain Mapping↗

PubMed1986

[Significance probability mapping of brain electrical activity--its problem and specified z-statistic mapping].

Significance probability mapping (SPM) of brain electrical activity first described by Duffy et al. is useful tool for studying functional aspects of brain disease. Z-statistic SPM is able to identify the area of brain electrical activity deviated with statistic significance from the control group. The problem of this method is, however, that the nature of deviation, i.e., whether it is increase or decrease of electrical activity, can not be displayed. From this point of view, we attempted to use modified z-statistic method. Statistically deviated region and its nature can be clearly displayed on the same picture by analyzing EEG with this method. This method can be applied to SPM of evoked potentials. SPM is not yet complete method for the assessment of brain electrical activity, but there is much room for adopting other statistic method that is more suitable for the aim of the study. Functional aspects of the brain will be more readily clarified by the use of modified SPM and by combination with findings of CT scan, NMR and PET that can give morphological and metabolic information.

Adult↗

PubMed2000

Mathematical/computational challenges in creating deformable and probabilistic atlases of the human brain.

Striking variations in brain structure, especially in the gyral patterns of the human cortex, present fundamental challenges in human brain mapping. Probabilistic brain atlases, which encode information on structural and functional variability in large human populations, are powerful research tools with broad applications. Knowledge-based imaging algorithms can also leverage atlased information on anatomic variation. Applications include automated image labeling, pathology detection in individuals or groups, and investigating how regional anatomy is altered in disease, and with age, gender, handedness and other clinical or genetic factors. In this report, we illustrate some of the mathematical challenges involved in constructing population-based brain atlases. A disease-specific atlas is constructed to represent the human brain in Alzheimer's disease (AD). Specialized strategies are developed for population-based averaging of anatomy. Sets of high-dimensional elastic mappings, based on the principles of continuum mechanics, reconfigure the anatomy of a large number of subjects in an anatomic image database. These mappings generate a local encoding of anatomic variability and are used to create a crisp anatomical image template with highly resolved structures in their mean spatial location. Specialized approaches are also developed to average cortical topography. Since cortical patterns are altered in a variety of diseases, gyral pattern matching is used to encode the magnitude and principal directions of local cortical variation. In the resulting cortical templates, subtle features emerge. Regional asymmetries appear that are not apparent in individual anatomies. Population-based maps of cortical variation reveal a mosaic of variability patterns that segregate sharply according to functional specialization and cytoarchitectonic boundaries.

Aged↗

PubMed1995

[The topographic EEG mapping of patients with an organic brain lesion].

Brain mapping was carried out in 50 patients with organic brain lesions (tumors, disturbances of vascular circulation, multiple sclerosis, consequences of brain trauma ets.) The parallelism between the severity of the organic brain lesion and the degree of bioelectrical activity disturbances has been discovered. In patients with brain tumors, consequences of the stroke, severe trauma and multiple sclerosis the focuses of pathological activity corresponded to location of the brain lesion.

Adolescent↗

PubMed1996

Microstates in language-related brain potential maps show noun-verb differences.

Brain processing of grammatical word class was studied analyzing event-related potential (ERP) brain fields. Normal subjects observed a randomized sequence of single German nouns and verbs on a computer screen, while 20-channel ERP field map series were recorded separately for both word classes. Spatial microstate analysis was applied, based on the observation that series of ERP maps consist of epochs of quasi-stable map landscapes and based on the rationale that different map landscapes must have been generated by different neural generators and thus suggest different brain functions. Space-oriented segmentation of the mean map series identified nine successive, different functional microstates, i.e., steps of brain information processing characterized by quasi-stable map landscapes. In the microstate from 116 to 172 msec, noun-related maps differed significantly from verb-related maps along the left-right axis. The results indicate that different neural populations represent different grammatical word classes in language processing, in agreement with clinical observations. This word class differentiation as revealed by the spatial-temporal organization of neural activity occurred at a time after word input compatible with speed of reading.

Adult↗

PubMed1992

[Topographic mapping of electric activity of the brain].

Quantitated neurophysiology and topographic brain mapping are reviewed. Certain information on the electrical activity of the brain may be more easily comprehended with the aid of topographic visualization of EEG and evoked potentials. Quantitated neurophysiology promises to make an important contribution to research in several fields of neuroscience, e.g. cognitive processing, psychiatry, dementia, epilepsy, cerebrovascular disorders, auditory and visual electrophysiology, and migraine. Provided that careful attention is paid to the elimination of artefacts, such methods may also be used as supplementary diagnostic tools in the clinic.

Brain↗

PubMed1988

Topographic mapping of brain electrical activity in the assessment of central auditory nervous system pathology.

Topographic mapping of brain electrical activity is a method of converting electrical measurements of brain activity (evoked potential and EEG) into quantitative data that then can be displayed as colored visual maps. In this article, we review the basic principles underlying the procedures involved and then discuss their use in the assessment of central auditory nervous system (CANS) pathology. Finally, we highlight some of the limitations of the procedures as presently used.

Adult↗

PubMed2006

Maximum contrast beamformer for electromagnetic mapping of brain activity.

Beamforming technique can be applied to map the neuronal activities from magnetoencephalographic/electroencephalographic (MEG/EEG) recordings. One of the major difficulties of the scalar-type MEG/EEG beamformer is the determination of accurate dipole orientation, which is essential to an effective spatial filter. This paper presents a new beamforming technique which exploits a maximum contrast criterion to maximize the ratio of the neuronal activity estimated in a specified active state to the activity estimated in a control state. This criterion leads to a closed-form solution of the dipole orientation. Experiments with simulation, phantom, and finger-lifting data clearly demonstrate the effectiveness, efficiency, and accuracy of the proposed method.

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PubMed1997

Topographic mapping of brain electrical activity in children with food-induced attention deficit hyperkinetic disorder.

UNLABELLED: In 15 children suffering from food induced attention deficit hyperkinetic syndrome, topographic EEG mapping of brain electrical activity was carried out following avoidance and ingestion of previously identified provoking foods. A crossover design was used and recordings were interpreted independently by two investigators, one of whom was blind to the order of testing. During consumption of provoking foods there was a significant increase in betal activity in the frontotemporal areas of the brain. This investigation is the first one to show an association between brain electrical activity and intake of provoking foods in children with food-induced attention deficit hyperactivity disorder. CONCLUSIONS: These data support the hypothesis that in a subgroup of children with attention deficit hyperactivity disorder certain foods may not only influence clinical symptoms but may also alter brain electrical activity.

Adolescent↗

PubMed2003

Mapping form and function in the human brain: the emerging field of functional neuroimaging in cortical malformations.

Malformations of cortical development (MCDs) are increasingly being recognized as a common cause of epilepsy in cases previously felt to be cryptogenic. MCDs occur when the normal process of cerebral cortical development is disrupted, and include disorders of neuronal proliferation, migration, and organization. Many have a genetic basis and the genes responsible for some MCDs have been identified. MCDs represent a unique and valuable substrate in functional brain mapping studies, since as developmental lesions they provide complementary information to studies performed on patients with acquired brain lesions. In recent years an increasing number of functional neuroimaging methods, including positron emission tomography, single photon emission computed tomography, magnetic resonance spectroscopy, and functional magnetic resonance imaging, have been applied to patients with MCDs. In this review we highlight some of the prominent findings in this emerging field by presenting the functional neuroimaging characteristics of selected MCDs.

Brain Diseases↗

PubMed2000

Event-related potentials correlate with task-dependent glucose metabolism.

Cognitive processing is associated with brain electrical activity that is reflected in event-related potentials (ERP). ERP during a target detection task, and regional cerebral glucose metabolism (CMRglc) measured simultaneously, may be influenced by the same neurophysiologic processes. We tested the hypothesis that ERP factors could be directly correlated with CMRglc to derive functional brain maps of brain activity at 120, 160, 200, 280, and 400 ms following stimulus presentation in a target detection task. We controlled for the potential confounding effects of age, sex, and task accuracy, and correlate target-related and nontarget-related ERP separately. Increases and decreases in CMRglc at each time point were identified with statistical parametric mapping (P < 0.001, uncorrected). The 120- and 160-ms maps were the same for target and nontarget processing, while maps for 280 and 400 ms clearly distinguished between targets and nontargets. Extrinsic (early) cognitive processes that depend mainly on stimulus characteristics show less variation based on stimulus meaning (i.e., letter vs shape; target vs nontarget) than later (intrinsic) cognitive processes. These early effects are lateralized to the left hemisphere, for negative ERP factors, and positive ERP-PET correlations are more likely than negative ERP-PET correlations. Thus, brain areas related to task processing impact both ERP and CMRglc measures, suggesting a shared neurophysiologic mechanism for negative ERP factors and increased CMRglc. Direct statistical analysis of these two measures using statistical parametric mapping provides high spatial and temporal resolution in multisubject experiments, while requiring only a single (18)FDG PET scan per subject.

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