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PubMed1995

Comparison of Z and multivariate statistical brain electromagnetic maps for the localization of brain lesions.

Conventional Z maps provide probability statements about the deviation of observed values from the norm. Galán et al. (1994) introduced Simultaneous Significance Probability Scales to detect abnormalities over the whole map, making use of the information provided by the topographic structure of dependencies. They also described multivariate brain electromagnetic (MBE) maps for compact presentation of complex spatio-temporal information. In this paper, using the distance-based localization receiver operating characteristic curves (DL-ROC curves), we compare the localization provided by computed tomography with that provided by Z and MBE maps in 61 patients with brain lesions. Maps were calculated for absolute power and relative power in delta, theta, alpha and beta bands for voltage and current source densities (CSD). In each patient, all maps were compared and the map with the highest value of the area of the DL-ROC curve was considered to be the "best map." Z maps of CSD were the "best maps" in 24 patients. In the voltage montage, we observed that multivariate maps add some information not contained in the Z maps. However, for CSD, Z maps were more accurate than multivariate maps. A very consistent finding was the observation that lesions were better detected by maps analyzing the delta band, while edema was better represented by maps in the theta range.

Brain Damage, Chronic↗
PubMed2001

18F-FDG PET mapping of regional brain activity in runners.

BACKGROUND: To examine regional metabolic changes in the human brain induced by free running in upright posture. METHODS. EXPERIMENTAL DESIGN: Regional brain changes in glucose uptake induced by running were examined by comparing brain images obtained by positron emission tomography (PET) and 18F-fluorodeoxyglucose (FDG). SETTING: The study was conducted at a research institute and involved participation of healthy young volunteers. Data sampling and analysis required special imaging device and special computer hardware/software. PARTICIPANTS: Subjects were 17 healthy male volunteers. They were divided at random into two equal groups, those who ran 4-5 km and the others sat in the room. MEASURES: differences in regional cerebral glucose uptake between runners and control groups were assessed statistically. Plasma glucose level was also measured and global cerebral uptake was estimated. RESULTS: Running was associated with a relative increase of glucose uptake in the temporoparietal association cortex, occipital cortex, premotor cortex and the cerebellar vermis. The highest activity was noted in the temporoparietal association cortex. Activity of the primary sensorimotor cortex was higher in the superomedial part (leg motor area) than the lateral part (thorax and arm). CONCLUSIONS: Running augmented energy consumption in the parieto-occipital region relative to the motor area, probably due to the higher energy consumption necessary for integration of multimodal sensory information than for generation of motor output. Our results indicate that FDG PET is a useful tool for brain mapping under various physiological conditions.

Adult↗
PubMed2005

Comparison of conventional region of interest and statistical mapping method in brain single-photon emission computed tomography for prediction of hyperperfusion after carotid endarterectomy.

OBJECTIVE: Hyperperfusion after carotid endarterectomy (CEA) has been proposed as the main mechanism of intracerebral hemorrhage, which is a disastrous complication. The aim of this study was to compare the predictive value of cerebral blood flow (CBF) abnormalities for hyperperfusion after CEA with the conventional region of interest (ROI) analysis and statistical brain mapping analysis. METHODS: For 46 patients with unilateral carotid stenosis of 70% or more, CBF and cerebral vasoreactivity were investigated with resting and acetazolamide-challenge single-photon emission computed tomography before CEA and 1 day after CEA. Three-dimensional stereotactic surface projection (3-D-SSP) analysis of CBF changes was performed by automatic quantification with a predefined template. RESULTS: Logistic regression analysis demonstrated CBF reduction (z-score) to be the only significant variable for postoperative hyperperfusion on 3-D-SSP with thalamic normalization but no significant variable with the ROI method. Receiver operating characteristic (ROC) analysis demonstrated significant improvement in the predictive value of CBF reduction (z-score) on 3-D-SSP (area under the ROC curve = 0.93) in comparison with the ROI method (area under the ROC curve = 0.78) (P = 0.049). According to the optimal cutoff values provided by ROC analysis, patients were categorized into two groups: Type I (CBF decrease < 20%, n = 23) and Type II (CBF decrease > or = 20%, n = 23) on ROI analysis and Type A (z-score < or = 2, n = 40) and Type B (z-score > 2, n = 6) on 3-D-SSP. There was a significant difference in incidence of hyperperfusion between Type A (1 of 40) and Type B (5 of 6) on 3-D-SSP (P = 0.00003) but not between Type I (1 of 23) and Type II (5 of 23) on ROI analysis. Cerebral vasoreactivity did not show significant value in the prediction of hyperperfusion with either the ROI or the 3-D-SSP method. CONCLUSION: Objective assessment of CBF status, especially baseline CBF reduction (z-score), with automatic quantification by 3-D-SSP with normalization had a higher diagnostic value than conventional ROI analysis to identify patients at risk for hyperperfusion after CEA.

Acetazolamide↗
PubMed1989

Multisite phosphorylation of microtubule-associated protein 2 (MAP-2) in rat brain: peptide mapping distinguishes between cyclic AMP-, calcium/calmodulin-, and calcium/phospholipid-regulated phosphorylation mechanisms.

Microtubule-associated protein 2 (MAP-2), a cytoskeletal protein of 280 kilodalton that is highly enriched in dendrites and neuronal perikarya, is subject to both cyclic AMP-, calcium/calmodulin-, and calcium/phospholipid-regulated phosphorylation when incubated with [gamma-32P]ATP in vitro. We have analyzed the different sites in MAP-2 phosphorylated by these three kinases in fresh or boiled cytosol from different regions of the rat brain, in particular the olfactory bulb, where only one form (MAP-2B) is present, and the cerebral cortex, where both forms (MAP-2A and MAP-2B) are equally enriched. Cyclic AMP-dependent protein kinase and calcium/calmodulin-dependent protein kinase II phosphorylated four common phosphorylation sites, as well as a number of distinct sites that were unique to each enzyme. Calcium/phospholipid-dependent protein kinase phosphorylated a minimum of 15 sites, only one of which appeared to be shared with the other protein kinases. Only serine residues were phosphorylated by cyclic AMP-dependent and calcium/phospholipid-dependent protein kinases, while both serine and threonine residues were phosphorylated by calcium/calmodulin-dependent protein kinase II. No differences were observed in the peptide maps of phospho-MAP-2 prepared from different brain regions. These results emphasize the complexity of the phosphorylation systems that may regulate the function of MAP-2 in situ.

Adenosine Triphosphate↗
PubMed2000

Utility of simultaneously acquired gradient-echo and spin-echo cerebral blood volume and morphology maps in brain tumor patients.

An interleaved gradient-echo (GE) / spin-echo (SE) EPI sequence was used to acquire images during the first pass of a susceptibility contrast agent, in patients with brain tumors. Maps of 1) GE (total) rCBV (relative cerebral blood volume), 2) SE (microvascular) rCBV, both corrected for T(1) leakage effects, and 3) (DeltaR(2)*/DeltaR(2)), a potential marker of averaged vessel diameter, were determined. Both GE rCBV and DeltaR(2)*/DeltaR(2) correlated strongly with tumor grade (P = 0.01, P = 0.01, n = 15), while SE rCBV did not (P = 0.24, n = 15). When the GE rCBV data were not corrected for leakage effects, the correlation with tumor grade was no longer significant (P = 0.09, n = 15). These findings suggest that MRI measurements of total blood volume fraction (corrected for agent extravasation) and DeltaR(2)*/DeltaR(2), as opposed to maps of microvascular volume, may prove to be the most appropriate markers for the evaluation of tumor angiogenesis (the induction of new blood vessels) and antiangiogenic therapies. Magn Reson Med 43:845-853, 2000.

Blood Volume↗
PubMed1976

Mapping the brain. Historical trends in functional localization.

This essay presents a brief review and evaluation of some guiding concepts during the past century of inquiry into localization of brain functions. Mapping methods are described and discussed as one useful set of approaches to defining functional localization. Each neurobiological discipline: neuroanatomy, neurophysiology, neurochemistry neuropsychology, neuroethology, clinical neurology, biophysics and bioengineering, all use map-making strategies in their search for valid spatial and temporal definitions of the phenomena in their field of interest. Particular emphasis is given to neurophysiological mapping procedures. How these procedures have evolved to become important tools for testing hypotheses about the neuroelectric, behavioral and psychological functions of specific neuroanatomical structures is discussed. The continued importance is emphasized of neurophysiological mapping as a basic set of descriptive sampling strategies for testing hypotheses about specific neural mechanisms and their adaptive operations.

Animals↗
PubMed2001

Metabolic mapping of brain regions associated with behavioral extinction in preweanling rats.

Fluorodeoxyglucose autoradiography, quantitative image analysis, and a multivariate tool (partial least squares) were used to assess distributed patterns of brain activation in postnatal day 17 and day 12 rat pups engaged in extinction of instrumental behavior. Pups were trained in a straight alley runway on an alternating reward schedule, or on a pseudorandom reward schedule, injected with fluorodeoxyglucose, and then shifted to continuous nonreward (extinction). Another group at each age served as handled controls. Day 17 pups trained on the alternating schedule demonstrated faster extinction rates compared to those trained on the pseudorandom schedule, a phenomenon known as the partial reinforcement extinction effect. No differences were found between day 12 groups. Partial least-squares analysis revealed age-related increases in fluorodeoxyglucose uptake across all three training conditions in the cingulate and frontal cortices, amygdala, midline thalamic nuclei, cerebellum, and in several brainstem regions. Training-related increases common to both age groups were found in the orbital frontal cortex, limbic thalamus, gigantocellular reticular nucleus, the somatosensory system, and cerebellum. Age-dependent training effects were found in the interpositus and medial cerebellar nuclei wherein fluorodeoxyglucose uptake increased in the day 12 alternation and pseudorandom groups relative to controls. Day 12 pups trained on the alternating schedule demonstrated increased uptake in the anterior dorsal thalamus relative to pseudorandom and control pups. Hence, a large-scale neural system comprised by somatosensory, cerebellar, and brainstem regions govern extinction behavior in preweanling rats. Recruitment of limbic structures may allow the older pups to modify extinction behavior based on prior learning.

Age Factors↗
PubMed2004

Genus zero surface conformal mapping and its application to brain surface mapping.

We developed a general method for global conformal parameterizations based on the structure of the cohomology group of holomorphic one-forms for surfaces with or without boundaries (Gu and Yau, 2002), (Gu and Yau, 2003). For genus zero surfaces, our algorithm can find a unique mapping between any two genus zero manifolds by minimizing the harmonic energy of the map. In this paper, we apply the algorithm to the cortical surface matching problem. We use a mesh structure to represent the brain surface. Further constraints are added to ensure that the conformal map is unique. Empirical tests on magnetic resonance imaging (MRI) data show that the mappings preserve angular relationships, are stable in MRIs acquired at different times, and are robust to differences in data triangulation, and resolution. Compared with other brain surface conformal mapping algorithms, our algorithm is more stable and has good extensibility.

Algorithms↗
PubMed2003

Genus zero surface conformal mapping and its application to brain surface mapping.

It is well known that any genus zero surface can be mapped conformally onto the sphere and any local portion thereof onto a disk. However, it is not trivial to find a general method which finds a conformal mapping between two general genus zero surfaces. We propose a new variational method which can find a unique mapping between any two genus zero manifolds by minimizing the harmonic energy of the map. We demonstrate the feasibility of our algorithm by applying it to the cortical surface matching problem. We use a mesh structure to represent the brain surface. Further constraints are added to ensure that the conformal map is unique. Empirical tests on MRI data show that the mappings preserve angular relationships, are stable in MRIs acquired at different times, and are robust to differences in data triangulation, and resolution. Compared with other brain surface conformal mapping algorithms, our algorithm is more stable and has good extensibility.

Algorithms↗
PubMed1999

Where the abstract feature maps of the brain might come from.

Three types of neuronal organization can be called 'brain maps': sets of feature-sensitive cells, ordered projections between neuronal layers and ordered maps of abstract features. The latter are most intriguing as they reflect the central properties of an organism's experiences and environment. It is proposed that such feature maps are learned in a process that involves parallel input to neurons in a brain area and adaptation of neurons in the neighborhood of the cells that respond most strongly to this input. This article presents a new mathematical formulation for such adaptation and relates it to physiological functions.

Algorithms↗
PubMed2005

[Intraoperative mapping of motor areas during brain tumor surgery: electrical stimulation patterns].

UNLABELLED: Brain mapping with direct electrical stimulation is usefull when the tumor is located near or has infiltrated the central lobe. OBJECTIVE: To analyze the surgical findings with direct electrical stimulation of the cortex and white matter under general anesthesia during surgery for brain tumors related to the central lobe. METHOD: We studied 42 patients operated on from June 2000 to June 2003. We analyzed surgical findings and details of brain mapping. RESULTS: The mean value of the intensity of the stimulus was greater among those who presented motor deficit prior to surgery (p = 0.0425) and edema on MRI (p = 0.0468) or during anesthesia with continuous propofol (p = 0.001). CONCLUSION: The functional mapping of the central lobe may be influenced by severe motor deficit, edema on MRI and propofol's anesthesia.

Adolescent↗
PubMed2003

Characterization and radiation hybrid mapping of expressed sequence tags from the canine brain.

Maps of the canine genome are now developing rapidly. Most of the markers on the current integrated canine radiation hybrid/genetic linkage/cytogenetic map are highly polymorphic microsatellite (type II) markers that are very useful for mapping disease loci. However, there is still an urgent need for the mapping of gene-based (type I) markers that are required for comparative mapping, as well as identifying candidate genes for disease loci that have been genetically mapped. We constructed an adult brain cDNA library as a resource to increase the number of gene-based markers on the canine genome map. Eighty-one percent of the 2700 sequenced expressed sequence tags (ESTs) represented unique sequences. The canine brain ESTs were compared with sequences in public databases to identify putative canine orthologs of human genes. One hundred nine of the canine ESTs were mapped on the latest canine radiation hybrid (RH) panel to determine the location of the respective canine gene. The addition of these new gene-based markers revealed three conserved segments (CS) between human and canine genomes previously detected by fluorescence in situ hybridization (FISH), but not by RH mapping. In addition, five new CS between dog and human were identified that had not been detected previously by RH mapping or FISH. This work has increased the number of gene-based markers on the canine RH map by approximately 30% and indicates the benefit to be gained by increasing the gene content of the current canine comparative map.

Animals↗
PubMed2004

Towards a new mapping of brain cortex function.

The aim of imaging neuroscience is to describe the functional organization of human brain at the level of large neuronal groupings, networks and systems. The systems level of description addresses how integrated brain functions are embodied in the physical structure of the brain. Magnetic resonance imaging is currently the technique of choice for the study of cerebral structure-function relationships and the analysis of structural and functional brain images can now be carried out automatically using statistical parametric mapping. The resultant ability to perform clinical-functional-anatomical correlative studies with complete objectivity and unparalleled sensitivity is providing powerful new opportunities for studying the relationship between structure and function, and how these parameters interact with pathology. One of the most exciting and dramatic observations to come from human brain mapping has been the dynamic plasticity of function in both normal brains and the brains of patients with neurological and neuropsychiatric disorders. Recent activation studies have provided interesting information about the brain's capacity to reorganize after injury and in association with practice and learning. The emerging studies of brain plasticity and its modulation by drugs and other therapies indicate potentially useful approaches to the rehabilitation of adults with brain damage, including damage resulting from cerebral ischaemia. Brain maps must therefore be viewed as dynamic, changing with development, disease progression, normal learning and in parallel with the recovery of function after acute injury. The dynamic plasticity of functional brain maps provides an exciting opportunity to study these processes.

Brain Mapping↗
PubMed1993

[Maps of visually evoked brain electrical activity in rabbits].

A basic model of topographic distribution of the electric response visually evoked in rabbits by means of flashes (0.69 joules/flash) has been obtained. The model is composed of four main parts--N0, P1, N1 y P2--linked to the VI visual area and displayed on a dipole shaped. The dipole turnaround time oscillates between 20 and 25 ms. The use of electrical activity brain maps on the study of the PE makes it possible to notice the phenomenon simultaneousness, thus facilitating its interpretation. A multinomial interpolation method of continuous function has been used to perform the maps.

Animals↗
PubMed1996

Visualization and mapping of neurosurgical functional brain data onto a 3-D MR-based model of the brain surface.

The Human Brain Project was initiated with the goal of developing methods for managing and sharing information about the brain. As a prototype Human Brain Project application we are developing a system for organizing, visualizing, integrating and sharing information about human language function. The goal of the brain mapping component of our work, described in this article, is to generate the 3D location and extent of cortical language sites with respect to a uniform, 3D patient coordinate system. The language sites of individual patients can then be combined with or related to other patient data in terms of a Talairach, surface-based, or other deformable coordinate systems. Language site mapping is done by visually comparing an intraoperative photograph with the rendered image (from MRI data). The techniques outlined in this article have been utilized to map cortical language sites of six patients. Preliminary results point to the adequacy of our volume visualizations for language mapping. The strength of the visualization scheme lies in the combination of interactive segmentation with volume and surface visualization. We are now in the process of acquiring more patient data to further validate the usefulness of our method.

Brain Mapping↗
PubMed2000

Molecular mapping of brain areas involved in parrot vocal communication.

Auditory and vocal regulation of gene expression occurs in separate discrete regions of the songbird brain. Here we demonstrate that regulated gene expression also occurs during vocal communication in a parrot, belonging to an order whose ability to learn vocalizations is thought to have evolved independently of songbirds. Adult male budgerigars (Melopsittacus undulatus) were stimulated to vocalize with playbacks of conspecific vocalizations (warbles), and their brains were analyzed for expression of the transcriptional regulator ZENK. The results showed that there was distinct separation of brain areas that had hearing- or vocalizing-induced ZENK expression. Hearing warbles resulted in ZENK induction in large parts of the caudal medial forebrain and in 1 midbrain region, with a pattern highly reminiscent of that observed in songbirds. Vocalizing resulted in ZENK induction in nine brain structures, seven restricted to the lateral and anterior telencephalon, one in the thalamus, and one in the midbrain, with a pattern partially reminiscent of that observed in songbirds. Five of the telencephalic structures had been previously described as part of the budgerigar vocal control pathway. However, functional boundaries defined by the gene expression patterns for some of these structures were much larger and different in shape than previously reported anatomical boundaries. Our results provide the first functional demonstration of brain areas involved in vocalizing and auditory processing of conspecific sounds in budgerigars. They also indicate that, whether or not vocal learning evolved independently, some of the gene regulatory mechanisms that accompany learned vocal communication are similar in songbirds and parrots.

Animals↗
PubMed2003

Efficient principal component analysis for multivariate 3D voxel-based mapping of brain functional imaging data sets as applied to FDG-PET and normal aging.

Principal component analysis (PCA) is a well-known technique for reduction of dimensionality of functional imaging data. PCA can be looked at as the projection of the original images onto a new orthogonal coordinate system with lower dimensions. The new axes explain the variance in the images in decreasing order of importance, showing correlations between brain regions. We used an efficient, stable and analytical method to work out the PCA of Positron Emission Tomography (PET) images of 74 normal subjects using [(18)F]fluoro-2-deoxy-D-glucose (FDG) as a tracer. Principal components (PCs) and their relation to age effects were investigated. Correlations between the projections of the images on the new axes and the age of the subjects were carried out. The first two PCs could be identified as being the only PCs significantly correlated to age. The first principal component, which explained 10% of the data set variance, was reduced only in subjects of age 55 or older and was related to loss of signal in and adjacent to ventricles and basal cisterns, reflecting expected age-related brain atrophy with enlarging CSF spaces. The second principal component, which accounted for 8% of the total variance, had high loadings from prefrontal, posterior parietal and posterior cingulate cortices and showed the strongest correlation with age (r = -0.56), entirely consistent with previously documented age-related declines in brain glucose utilization. Thus, our method showed that the effect of aging on brain metabolism has at least two independent dimensions. This method should have widespread applications in multivariate analysis of brain functional images.

Adult↗