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PubMed1988

Topographic brain mapping of middle latency auditory evoked potentials in normal subjects.

Topographic brain mapping of auditory middle latency evoked responses (MLR) were obtained from 20 subjects (10 males and 10 females), all right-handed and with normal pure tone audiograms. Clicks with alternative polarity, with a rate of 7.7/sec. were delivered at an intensity of 75 dB HL monoaurally to both ears. Responses from 21 channels were amplified and band-pass filtered (3-150). All the surface maps were analyzed with a Bio-Logic Brain Atlas III system. MLR maps obtained show a quite small intrasubjective variability at the latencies of the principal components Na and Pa. The grand averages of MLR maps at the corresponding latencies in males and females were compared each other. All the entire temporal window has been segmented into some subepochs, showing similar spatial characteristics of the maps, like location of maxima and minima and, overall, shape.

Adult↗
PubMed1999

Automated Talairach atlas-based parcellation and measurement of cerebral lobes in children.

This study applied a Talairach-based automated parcellation method, originally proposed for adults, to the measurement of lobar brain regions in pediatric study groups. Manual measures of lobar brain regions in a sample of 15 healthy boys, girls and adults were used initially to revise the original Talairach-based grid to increase its applicability to pediatric brains. The applicability of the revised Talairach grid was then tested on an independent sample of five girls with Rett syndrome. As Tables 3 and 4 in the text demonstrate, sensitivity, specificity and positive predictive values either remained unchanged or increased as a result of revising the sectors to fit the brains of children. High levels of sensitivity and specificity were achieved for all revised Talairach-based calculations in relation to the manual measures. Both positive predictive values and intraclass correlations between volumetric measures produced by the revised automated and manual methods varied with the relative size of the brain region. Values were relatively low for smaller structures such as the brainstem and subcortical region, and high for lobar regions. These results suggest that the automated Talairach atlas-based parcellation method can produce sensitive and specific volumetric measures of lobar brain regions in both normal children and children with brain disorders. Accordingly, the method holds much promise for facilitating quantitative pediatric neuroimaging research.

Adult↗
PubMed2004

Improved agreement between Talairach and MNI coordinate spaces in deep brain regions.

Disagreement between the Talairach atlas and the stereotaxic space commonly used in software like SPM is a widely recognized problem. Others have proposed affine transformations to improve agreement in surface areas such as Brodmann's areas. This article proposes a similar transformation with the goal of improving agreement specifically in the deep brain region. The task is accomplished by finding an affine transformation that minimizes the mean distance between the surface coordinates of the lateral ventricles in the Talairach atlas and the MNI templates. The result is a transformation that improves deep brain agreement over both the untransformed Talairach coordinates and the surface-oriented transformation. While the transformation improves deep brain agreement, surface agreement is generally made worse. For areas near the lateral ventricle, the transformation presented herein is valuable for applications such as region of interest (ROI) modeling.

Algorithms↗
PubMed1999

Mapping of secondary somatosensory cortex activation induced by vibrational stimulation: an fMRI study.

Sensory functional MRI was performed in seven normal volunteers at 1. 5 T using a vibratory stimulus applied to the pad of the first finger of the left hand. The data was normalized to a standard atlas, and individual and group statistical parametric maps were computed. Robust bilateral activation was demonstrated in the secondary somatosensory cortex (SII), indicating a bilateral representation of SII in humans. Greater maxima and activation volumes were achieved in contralateral SII as compared to SI. Sensory fMRI can provide a sensitive assay for probing the nature and function of SII in vivo.

Adult↗
PubMed2004

An empirical charge transfer potential with correct dissociation limits.

The empirical valence bond (EVB) method [J. Chem. Phys. 52, 1262 (1970)] has always embodied charge transfer processes. The mechanism of that behavior is examined here and recast for use as a new empirical potential energy surface for large-scale simulations. A two-state model is explored. The main features of the model are: (1) explicit decomposition of the total system electron density is invoked; (2) the charge is defined through the density decomposition into constituent contributions; (3) the charge transfer behavior is controlled through the resonance energy matrix elements which cannot be ignored; and (4) a reference-state approach, similar in spirit to the EVB method, is used to define the resonance state energy contributions in terms of "knowable" quantities. With equal validity, the new potential energy can be expressed as a nonthermal ensemble average with a nonlinear but analytical charge dependence in the occupation number. Dissociation to neutral species for a gas-phase process is preserved. A variant of constrained search density functional theory is advocated as the preferred way to define an energy for a given charge.

Journal Article↗
PubMed1989

Are "cervicogenic" headaches due to myofascial pain and cervical spine dysfunction?

The purpose of this investigation was to evaluate whether the pain of cervicogenic headache could be due to referred symptoms from myofascial trigger points. The presence or absence of cervical spine dysfunction was also of interest. Eleven patients with cervicogenic headaches were systematically examined for myofascial trigger points and cervical spine dysfunction. All patients had at least three myofascial trigger points on the symptomatic side. In eight of these patients, trigger point palpation clearly reproduced their headache. There were 70 myofascial trigger points (35 "very tender", 35 "tender") and 17 non-myofascial tender points on the symptomatic side, compared to 22 myofascial trigger points (one "very tender", 21 "tender") and 19 non-myofascial tender points on the asymptomatic side. These differences were statistically significant [chi-square (2df) = 22.04, p less than 0.0001]. All patients had some evidence of cervical dysfunction. Ten patients (91%) had specific segmental dysfunction of occiput on atlas and/or atlas on axis. Five patients were entered into a non-invasive, interdisciplinary pain management program designed to treat cervical spine dysfunction and myofascial pain. Treated patients reported a significant decrease in the frequency and intensity of their headaches during a median two-year follow-up. It is concluded that myofascial trigger points may be an important pain producing mechanism in cervicogenic headache and that segmental cervical dysfunction is a common feature in such patients. Conservative, non-surgical treatment appears to be effective in reducing the frequency and intensity of cervicogenic headache. These data suggest that surgical approaches should be reserved only for those patients who fail conservative therapy.

Adult↗
PubMed1998

SPECT brain perfusion abnormalities in mild or moderate traumatic brain injury.

The purpose of this atlas is to present a review of the literature showing the advantages of SPECT brain perfusion imaging (BPI) in mild or moderate traumatic brain injury (TBI) over other morphologic imaging modalities such as x-ray CT or MRI. The authors also present the technical recommendations for SPECT brain perfusion currently practiced at their center. For the radiopharmaceutical of choice, a comparison between early and delayed images using Tc-99m HMPAO and Tc-99m ECD showed that Tc-99m HMPAO is more stable in the brain with no washout over time. Therefore, the authors feel that Tc-99m HMPAO is preferable to Tc-99m ECD. Recommendations regarding standardizing intravenous injection, the acquisition, processing parameters, and interpretation of scans using a ten grade color scale, and use of the cerebellum as the reference organ are presented. SPECT images of 228 patients (age range, 11 to 88; mean, 40.8 years) with mild or moderate TBI and no significant medical history that interfered with the results of the SPECT BP were reviewed. The etiology of the trauma was in the following order of frequency: motor vehicle accidents (45%) followed by blow to the head (36%) and a fall (19%). Frequency of the symptoms was headache (60.9%), memory problems (27.6%), dizziness (26.7%), and sleep disorders (8.7%). Comparison between patients imaged early (<3 months) versus those imaged delayed (>3 months) from the time of the accident, showed that early imaging detected more lesions (4.2 abnormal lesions per study compared to 2.7 in those imaged more than 3 months after the accident). Of 41 patients who had mild traumatic injury without loss of consciousness and had normal CT, 28 studies were abnormal. Focal areas of hypoperfusion were seen in 77% (176 patients, 612 lesions) of the group of 228 patients. The sites of abnormalities were in the following order: basal ganglia and thalami, 55.2%, frontal lobes, 23.8%, temporal lobes, 13%, parietal, 3.7%, insular and occipital lobes together, 4.6%.

Adolescent↗
PubMed2005

Overview of the HUPO Plasma Proteome Project: results from the pilot phase with 35 collaborating laboratories and multiple analytical groups, generating a core dataset of 3020 proteins and a publicly-available database.

HUPO initiated the Plasma Proteome Project (PPP) in 2002. Its pilot phase has (1) evaluated advantages and limitations of many depletion, fractionation, and MS technology platforms; (2) compared PPP reference specimens of human serum and EDTA, heparin, and citrate-anti-coagulated plasma; and (3) created a publicly-available knowledge base (www.bioinformatics.med.umich.edu/hupo/ppp; www.ebi.ac.uk/pride). Thirty-five participating laboratories in 13 countries submitted datasets. Working groups addressed (a) specimen stability and protein concentrations; (b) protein identifications from 18 MS/MS datasets; (c) independent analyses from raw MS-MS spectra; (d) search engine performance, subproteome analyses, and biological insights; (e) antibody arrays; and (f) direct MS/SELDI analyses. MS-MS datasets had 15 710 different International Protein Index (IPI) protein IDs; our integration algorithm applied to multiple matches of peptide sequences yielded 9504 IPI proteins identified with one or more peptides and 3020 proteins identified with two or more peptides (the Core Dataset). These proteins have been characterized with Gene Ontology, InterPro, Novartis Atlas, OMIM, and immunoassay-based concentration determinations. The database permits examination of many other subsets, such as 1274 proteins identified with three or more peptides. Reverse protein to DNA matching identified proteins for 118 previously unidentified ORFs. We recommend use of plasma instead of serum, with EDTA (or citrate) for anticoagulation. To improve resolution, sensitivity and reproducibility of peptide identifications and protein matches, we recommend combinations of depletion, fractionation, and MS/MS technologies, with explicit criteria for evaluation of spectra, use of search algorithms, and integration of homologous protein matches. This Special Issue of PROTEOMICS presents papers integral to the collaborative analysis plus many reports of supplementary work on various aspects of the PPP workplan. These PPP results on complexity, dynamic range, incomplete sampling, false-positive matches, and integration of diverse datasets for plasma and serum proteins lay a foundation for development and validation of circulating protein biomarkers in health and disease.

Algorithms↗
PubMed1997

A magnetic resonance template for normal cerebellar development in the human fetus.

OBJECTIVE: Although ultrasound is the primary imaging modality for prenatal anatomic evaluation, some central nervous system malformations may be better defined with high-resolution magnetic resonance imaging (MRI). MRI allows us to visualize the features of brain development that were previously only seen histologically by embryologists and anatomists. Although there are several reports of the postnatal development of the cerebellum as revealed on magnetic resonance (MR) images, systematic MR studies of cerebellar development during the fetal period are lacking. Our objective was to use high-resolution MRI to provide a template of cerebellar development during the late first and early second trimesters, a period when the diagnosis of congenital malformations is most medicoethically relevant. The MR findings were then correlated with histological data. METHODS: Twenty-six normal formalin-fixed fetal specimens with a gestational age of 9 to 24 weeks were examined with high-resolution MRI using a conventional clinical magnet and pulse sequences. The MR findings were correlated with the whole-mount histological specimens catalogued in a well-known fetal atlas. RESULTS: Resolution of the morphological features of cerebellar development in fetuses greater than 10 weeks gestational age was possible. Development of the rhombic lips, vermis, fourth ventricular roof, foramen of Magendie, and the cerebellar fissures was documented. Development of the cerebellum as revealed on MR images lagged behind the known stages of development by as much as 5 weeks. Features of cerebellar histogenesis were beyond the resolution of MRI. However, differences in signal intensity between gray and white matter of the developing cerebellum were detected and are postulated to represent differences in cellularity and water content of the constituent tissues. CONCLUSION: Direct correlation of MR images of fetuses during the late first and early second trimesters with anatomic atlases could result in a mistaken diagnosis of delayed or abnormal development of the posterior fossa contents because of a time lag in the detection of structures on MR images. An MR template of normal cerebellar development would be useful to avoid confusion of normal development with abnormal development and to identify the expected developmental features when provided the estimated gestational age of a fetus.

Cerebellum↗
PubMed2002

The feasibility of a common stereotactic space for children and adults in fMRI studies of development.

The question of whether pediatric and adult neuroimaging data can be analyzed in a common stereotactic space is a critical issue for developmental neuroscience. Two studies were performed to address this question. In Study 1, high-resolution structural MR brain images of 20 children (7-8 years of age) and 20 young adults (18-30 years of age) were transformed to a common space. Overall brain shape was assessed by tracing the outer boundaries of the brains in three orientations, and more local anatomy was assessed by analysis of portions of 10 selected sulci. Small, but consistent, differences in location and variability were observed in specific locations of the sulcal tracings and outer-boundary sections. In Study 2, a computer simulation was used to assess the extent to which the small anatomical differences observed in Study 1 would produce spurious effects in functional imaging data. Results indicate that, assuming a functional resolution of 5 mm in images averaged across subjects, anatomical differences in either variability or location between children and adults of the magnitude obperved in Study 1 would not negatively affect functional image comparisons. We conclude that atlas-transformed brain morphology is relatively consistent between 7- and 8-year-old children and adults at a resolution appropriate to current functional imaging and that the small anatomical differences present do not limit the usefulness of comparing child and adult functional images within a common stereotactic space.

Adolescent↗
PubMed2004

Frontal and temporal sources of mismatch negativity in healthy controls, patients at onset of schizophrenia in adolescence and others at 15 years after onset.

Mismatch negativity (MMN) is an event-related potential measure of auditory change detection. It is widely reported to be smaller in patients with schizophrenia and may not improve along with otherwise successful clinical treatment. The main aim of this report is to explore ways of measuring and presenting four features of frequency-deviant MMN dipole sources (dipole moment, peak latency, brain location and orientation) and to relate these to the processes of psychopathology and illness progression. Data from early onset patients (EOS) at the start of the illness in adolescence, and others who had their first break in adolescence 15 years ago (S-15Y) were compared with two groups of age-matched healthy controls (C-EOS, C-15Y). A four-source model fitted the MMN waveform recorded from all four groups, whether MMN amplitude was more (EOS) or less (S-15Y) reduced. The locations were in the left superior temporal and anterior cingulate gyri, right superior temporal and inferior/mid frontal cortices. Dipole latencies confirmed a bottom-up sequence of processing and dipole moments were larger in the temporal lobes and on the left. Patients showed small dipole location changes that were more marked in the S-15Y than the EOS group (more rostral for the left anterior cingulate, more caudal for the right mid-frontal dipole) consistent with illness progression. The modelling of MMN dipole sources on brain atlas and anatomical images suggests that there is a degree of dissociation during illness between small progressive anatomical changes and some functional recovery indexed by scalp recordings from patients with an onset in adolescence 15 years before compared to adolescents in their first episode.

Adolescent↗
PubMed1995

A 3D digital map of rat brain.

A three dimensional (3D) computerized map of rat brain anatomy created with digital imaging techniques is described. Six male Sprague-Dawley rats, weighing 270-320 g, were used in the generation of this atlas. Their heads were frozen, and closely spaced cryosectional images were digitally captured. Each serial data set was organized into a digital volume, reoriented into a flat skull position, and brought into register with each other. A volume representative of the group following registration was chosen based on its anatomic correspondence with the other specimens as measured by image correlation coefficients and landmark matching. Mean positions of lambda, bregma, and the interaural plane of the group within the common coordinate system were used to transform the representative volume into a 3D map of rat neuroanatomy. images reconstructed from this 3D map are available to the public via Internet with an anonymous file transfer protocol (FTP) and World Wide Web. A complete description of the digital map is provided in a comprehensive set of sagittal planes (up to 0.031 mm spacing) containing stereotaxic reference grids. Sets of coronal and horizontal planes, resampled at the same increment, also are included. Specific anatomic features are identified in a second collection of images. Stylized anatomic boundaries and structural labels were incorporated into selected orthogonal planes. Electronic sharing and interactive use are benefits afforded by a digital format, but the foremost advantage of this 3D map is its whole brain integrated representation of rat in situ neuroanatomy.

Animals↗
PubMed2002

Effect of magnification on lateral cephalometric studies.

The effect of radiographic magnification on the horizontal distance sella-nasion, the vertical distance nasion-menton, and the oblique distance sella-gnathion was explored. Five different longitudinal cephalometric studies provided the data for this survey. Two series of graphs were created: 1 from the raw data as they originally were published, the other in natural size after meticulous compensation for radiographic magnification. The importance of correction for magnification at once became obvious when these graphs were reviewed. The following conclusions were made: the distances listed in commonly used cephalometric atlases differ greatly because of different magnification and cannot be compared directly. The distances from the Ann Arbor, Michigan, study must be multiplied by 0.886, and those from the Bolton Standards and the Philadelphia studies must be multiplied by 0.943 to obtain natural dimensions. Correction to natural size is essential when comparing cephalometric distances from different sources; publication of data corrected to an arbitrary "standardized enlargement" creates confusion. Although differences between the corrected distances were small, regional variation seems to exist.

Adolescent↗
PubMed1999

Automatic 3-D segmentation of internal structures of the head in MR images using a combination of similarity and free-form transformations: Part II, validation on severely atrophied brains.

Studies aimed at quantifying neuroanatomical differences between populations require the volume measurements of individual brain structures. If the study contains a large number of images, manual segmentation is not practical. This study tests the hypothesis that a fully automatic, atlas-based segmentation method can be used to quantify atrophy indexes derived from the brain and cerebellum volumes in normal subjects and chronic alcoholics. This is accomplished by registering an atlas volume with a subject volume, first using a global transformation, and then improving the registration using a local transformation. Segmented structures in the atlas volume are then mapped to the corresponding structures in the subject volume using the combined global and local transformations. This technique has been applied to seven normal and seven alcoholic subjects. Three magnetic resonance volumes were obtained for each subject and each volume was segmented automatically, using the atlas-based method. Accuracy was assessed by manually segmenting regions and measuring the similarity between corresponding regions obtained automatically. Repeatability was determined by comparing volume measurements of segmented structures from each acquisition of the same subject. Results demonstrate that the method is accurate, that the results are repeatable, and that it can provide a method for automatic quantification of brain atrophy, even when the degree of atrophy is large.

Alcohol-Induced Disorders, Nervous System↗
PubMed1998

The correlation between surface measurement of head and neck posture and the anatomic position of the upper cervical vertebrae.

STUDY DESIGN: Repeated measurements were made of surface postural angles registering the relative positions of the head and neck in photographs and of angles of the upper cervical vertebrae recorded in lateral cephalometric radiographs in the same subjects. For all registrations, subjects assumed the natural head rest position. OBJECTIVES: To examine the correlation between external measurement of head and neck posture and the anatomic positions of the upper four cervical vertebrae. SUMMARY OF BACKGROUND DATA: Interpretation of surface cervical posture measurement is confounded by lack of knowledge about the extent of the underlying compensatory adjustments among the upper cervical vertebrae that may accompany variation in head and neck posture. The correlation between surface measurement and postural characteristics of the upper cervical spine has not been reported to date. METHODS: The association between a set of angles describing the anatomic position of the four upper cervical vertebrae on lateral cephalometric radiographs and a surface measurement of head and neck posture, the craniovertebral angle, was studied in 34 young adult women aged between 17.2 and 30.5 years, mean age, 24.5 years. Anatomic positions of the upper four cervical vertebrae were expressed by angles relative to the true vertical or horizontal. Surface angles registering head and neck position for each subject were obtained from photographs recorded on two occasions. RESULTS: No strong correlation could be established between the angles taken from the lateral cephalometric radiographs measuring the extent of upper cervical lordosis, orientation of the atlas, vertebral inclination, or odontoid process tilt and surface angles recording head and neck position. This finding was attributed principally to the much greater positional variability demonstrated within the upper cervical spine when compared with the surface measurements of head and neck position. CONCLUSION: Anatomic alignment of the upper cervical vertebrae cannot be inferred from variation in surface measurement of head and neck posture. This is the case even in those people identified with more extreme head and neck postural tendencies.

Adolescent↗
PubMed2000

Sleep atlas and multimedia database.

The ENN sleep atlas and database was set up on a dedicated server connected to the internet thus providing all services such as WWW, ftp and telnet access. The database serves as a platform to promote the goals of the European Neurological Network, to exchange patient cases for second opinion between experts and to create a case-oriented multimedia sleep atlas with descriptive text, images and video-clips of all known sleep disorders. The sleep atlas consists of a small public and a large private part for members of the consortium. 20 patient cases were collected and presented with educational information similar to published case reports. Case reports are complemented with images, video-clips and biosignal recordings. A Java based viewer for biosignals provided in EDF format was installed in order to move free within the sleep recordings without the need to download the full recording on the client.

CD-ROM↗
PubMed2001

Template images for nonhuman primate neuroimaging: 2. Macaque.

Neuroimaging studies are increasingly performed in macaque species, including the pig-tailed macaque (Macaca nemestrina). At times experimental questions can be answered by analysis of functional images in individual subjects and reference to a structural image in that subject. However, coregistration of functional brain images across many subjects offers the experimental advantage of enabling voxel-based analysis over multiple subjects and is therefore widely used in human studies. Voxel-based coregistration methods require a high-quality 3D template image. We created such templates, derived from T1-weighted MRI and blood-flow PET images from 12 nemestrina monkeys. We designed the macaque templates to be maximally compatible with the baboon template images described in a companion paper, to facilitate cross-species comparison of functional imaging data. Here we present data showing the reliability and validity of automatic image registration to the template. Alignment of selected internal fiducial points was accurate to within 1.9 mm overall (mean) even across species. The template images, along with copies aligned to the UCLA nemestrina brain atlas, are available on the Internet (purl.org/net/kbmd/n2k) and can be used as targets with any image registration software.

Animals↗
PubMed2001

The challenges and rewards of integrating diverse neuroscience information.

The design of database models and schemas for storing, cross-referencing, and retrieving neuroscience information faces issues that are similar but more complex than most of the other biomedical disciplines, such as genomics and proteonomics. Specifically, the visualization and manipulation of very large and diverse image data, such as digital brain atlases and functional magnetic resonance images, play a unique role in neuroscience while much of the associated information is textually recorded. Nongraphical information can include the annotation of large brain structures ranging from anatomical regions to intracellular structures, the description of cellular functional properties, and their various interrelationships, such as fiber connections. It is necessary that the heterogeneous and distributed types of data be cross-referenced to each other so that this diverse information can be efficiently retrieved, shared, and exchanged among the different neuroscientific disciplines. Continued advances in computers and Internet technologies appear to indicate that increasingly large data sets will be maintained on local or regional file servers and that informational interoperability will be achieved using a networked information system infrastructure. The authors and others have proposed and implemented models of semantically organized information systems that utilize centrally stored and highly structured archival information to index, cross-reference, and retrieve diverse, Web-based data sets.

Brain↗