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At least 145 records · Page 8Linked to original sources

Scintigraphic assessment of regional cardiac adrenergic innervation.

To assess the feasibility of noninvasively imaging the regional distribution of myocardial sympathetic innervation, we evaluated the distribution of sympathetic nerve endings, using 123I metaiodobenzylguanidine (MIBG), and compared this with the distribution of myocardial perfusion, using 201Tl. Twenty dogs were studied: 11 after regional denervation, and nine as controls. Regional denervation was done by left stellate ganglion removal, right stellate ganglion removal, and application of phenol to the epicardial surface. Computer-processed functional maps displayed the relative distribution of MIBG and thallium in multiple projections in vivo and excised heart slices in all animals. In six animals, dual isotope emission computed tomograms were acquired in vivo. Tissue samples taken from innervated and denervated regions of the MIBG images were analyzed for norepinephrine content to validate image findings. Normal controls showed homogeneous and parallel distributions of MIBG and thallium in the major left ventricular mass. In the left stellectomized hearts, MIBG was reduced relative to thallium in the posterior left ventricle; whereas in right stellectomized hearts, reduced MIBG was in the anterior left ventricle. Phenol-painted hearts showed a broad area of decreased MIBG extending beyond the area of phenol application. In both stellectomized and phenol-painted hearts, thallium distribution remained homogeneous and normal. Norepinephrine content was greater in regions showing normal MIBG (550 +/- 223 ng/g) compared with regions showing reduced MIBG (39 +/- 44 ng/g) (p less than 0.001), confirming regional denervation. Combined MIBG-thallium functional maps display the regional distribution of sympathetic innervation. This new ability to noninvasively map the distribution of sympathetic nerves with simultaneous comparison to regional perfusion may provide important new insights into mechanisms, whereby an imbalance in sympathetic activity may relate to clinical disorders.

3-Iodobenzylguanidine

Serial movement timing and musical experience.

Musicians and non-musicians were compared on a serial movement-timing task incorporating six continuous 11-cm segments. The serial pattern was structured for both spatial and temporal symmetry. There were seven subjects in each group and 50 test trials were analyzed for timing error. The non-musicians were less accurate and more variable for certain parts of the pattern. The findings supported the view that musical practice can assist the process of mapping internal representations of serial relations to novel spatio-temporal patterns of movement.

Adult

Functional magnetic resonance imaging of the brain.

This conference reviewed the potential scope of application of recently developed techniques for functional magnetic resonance imaging (fMRI) of the brain. The most successful technique is based on the sensitivity of magnetic resonance imaging (MRI) to magnetic effects caused by the modulation of the oxygenation state of hemoglobin, which is induced by local variations in blood flow during task activation. Typically, the MRI signal increases by a few percentage points during brain activation because blood flow and oxygen supply sharply increase. Brain activation images with excellent combined spatial and temporal resolution have been obtained noninvasively using visual, sensorimotor, or auditory stimuli, or during higher-order cognitive processes such as language or mental imagery. Although sensitive to misregistration artifacts and macroscopic vessels, MRI permits both the direct correlation of function with underlying anatomy and repeated studies on the same person. It may become the method of choice for studies of mental and cognitive processes, presurgical mapping, monitoring recovery from stroke or head injuries, exploration of seizure disorders, or monitoring the effects of neuropharmaceuticals.

Animals

Courage and curiosity: surgeon-explorers in Australia and New Zealand. Part II. The science of the outback. The Herbert Moran Lecture concluded.

After the broad brush of the topographical features of Australia and New Zealand had been mapped, the process of fine-tuning the geographic details of these countries continued. In parallel with this, a great wave of detailed scientific exploration proceeded and it was to these expeditions that medical men brought special skills. Surgeons played a special role because of the need of their practical skills in the field. Dozens of expeditions were commissioned throughout the nineteenth century. The aim of some was to search for minerals and document the fertility and water supply for pastoral and agricultural lands. Others had as their major raison d'etre the documentation of the many groups of animals and plants which populated these domains new to Western science. Surgeons and physicians were valued not only for their professional skills in the field, but for the pursuit of botany, zoology and geology, and in many cases for ethnological studies as well.

Anthropology

Effect of physiological and pathological aging processes on topographic bit-mapped cognitive evoked potentials in presenile subjects.

Bit-mapped multicomponent CNV complex and reaction time (RT) were recorded and measured in 24 presenile patients with initial symptoms of very mild to moderately severe primary mental deterioration without depression, and in 10 age-matched controls. All patients underwent CT and MRI examinations, EEG spectral analysis and a battery of psychometric test. Significant group differences were obtained for measures of some post-S1 ERP and CNV components, particularly of the post-S1 N1b, P300 and early and late pre-S2 CNV. P300 with increased latency, no significant CNV activity, very prolonged RTs, EEG slowing down and diffuse brain atrophy were observed in the majority of patients with probable presenile Alzheimer's dementia. These results suggest that CNV/RT and EEG activity changes similar to those observed in our patients may constitute a valuable clue for the study of brain dysfunction in the early stage of presenile idiopathic cognitive impairment.

Aged

A rhythmically discharging neuron in the earthworm ventral cord nerve as identified by lucifer yellow-CH injection.

In the process of mapping the ganglionic neurons in the earthworm ventral nerve cord by simultaneous recording and Lucifer Yellow-CH injection or by backfilling, a rhythmically discharging neuron with a continuous train of 100 cps over the entire recording period was encountered at the dorsal side of the cord near the base of the 2nd-3rd nerves, with its axon extending toward the 2nd-3rd contralateral nerves. It could not be determined whether branches of this axon entered these contralateral nerves. The rhythmic discharge could not be recorded extracellularly from the nerves or from the cord by suction or hook electrodes, nor did the cell respond to either intra- or extracellular stimulation through the recording and injection microelectrode. Although contralateral neurons have been described in histological works, this neuron may not be identifiable one of them until its relationship with other neurons becomes clear.

Animals

Detection of enzootic territories and exploration of tularemia epizootics in different types of natural foci of this infection by serological examination of bird pellets and the excrements of beasts of prey.

Serological analysis (reaction of antibody neutralization) of pellets of birds and excrements of beasts of prey for the presence of tularemia microbe antigen is an efficient method of detection and investigation of epizootics in all types of natural foci of the infection and also for the exploration of new focal territories. The method permits with small expenditure of labour and within a short time, to collect material characterizing the epizootic process on a large territory. Tularemia epizootics, both having taken place in the past and ruinning at the moment of observation, are detected. It is possible to carry out the observations even in the years of a reduced number of the main carriers of the agent of tularemia and thus to trace the continuity of the epizootic process. The obtained data permit to establish the essential characteristics of the epizootic process. Detailed maps of the foci can be drawn and territories of stable preservation of infection detected.

Animals

The effect of textual variation on concept based information retrieval.

Accounting for textual variation in the documents and queries processed by information retrieval systems is considered essential for achieving good retrieval. Recent research has called into question several of the techniques used to support this endeavor. This paper reports on experiments with a concept based information retrieval system which relies on a program called MetaMap to account for textual variation in the process of mapping biomedical text such as MEDLINE bibliographic citations to the UMLS Metathesaurus. The experiments confirm that the effort expended in handling textual variation is well-spent for at least one type of concept based information retrieval.

Information Storage and Retrieval

EEG- and EP-mapping--possible indicators for disturbed information processing in schizophrenia?

1. Schizophrenic patients have been investigated electroencephalographically to describe disturbed information processing mechanisms. 2. 16-channel quantitative EEG and P300 were recorded at resting conditions before and during neuroleptic depot injection. 3. Reduced occipital alpha-power and alpha-power dependent P300-amplitudes were found in the schizophrenics. 4. Hippocampal structures are involved in the disturbed information processing mechanisms.

Adult

[Systems organization of the electrical activity of the brain in recognizing a visual image based on data from the mapping of interconnection indices].

Eight subjects were studied by the method of topographic mapping of interconnection characteristics of the human brain electrical activity in the process of recognition of visual images. The method used in our studies differs from others by the fact that properties of the processes interconnections are mapped but not the characteristics of the very processes. Under recognition of images the relief of topographic map of interconnections of cortical electrical processes increases in the right and decreases in the left frontal areas. Thus both hemispheres participate in this process. The hypothesis is suggested about two types of spatial synchronization: of similar electrical activity and of the activity differentiated in the brain sections. The developed method proved to be informative for the studied structure of spatial-temporal organization of the human brain electrical activity.

Adolescent

The roles of microtubule-associated proteins in brain morphogenesis: a review.

Microtubule-associated proteins (MAPs) are a diverse family of cytoskeletal proteins that copurify with tubulin in vitro. Recently a number of novel approaches have been used to learn more about the functions of MAPs during brain development, including: localization of MAPs and their mRNA in the developing brain, comparisons of MAPs between species to learn potential fundamental characteristics, biochemical analysis of changes in MAPs in process-bearing cell lines, and sequence analysis of MAP cDNAs and cDNA transfection studies. Taken together, these data allow us to assign roles to MAPs which are abundant in the developing brain, and to develop models for future studies. Four MAPs are particularly abundant in the developing brain: MAP1B, the high and low-molecular weight forms of MAP2, and juvenile tau. MAP1B is the only MAP to be found consistently in extending processes in both the developing and adult brain, making it a likely regulator of neurite outgrowth. High-molecular weight MAP2 and tau crosslink microtubules in dendrites and axons, respectively. Low-molecular weight MAP2 may be able to regulate MAP2-mediated crosslinking to make processes more labile during development and in adult brain regions where synaptogenesis is active. Tau-mediated crosslinking may be regulated by temporal regulation of the expression of tau forms with different binding affinities to tubulin. High-molecular weight MAP2 is sequestered into dendrites by the selective transport of its mRNA. This allows rapid and local regulation of MAP2 synthesis.

Aging

Effects of left anterior fascicular block on the depolarization process as depicted by total body surface mapping.

To examine the effects of left anterio fascicular block (LAFB) on the depolarization process as manifested on the body surface, 142 lead maps were recorded in 25 subjects with LAFB. Three abnormalities were detected: (1) In the early and mid portion of QRS, twenty of 25 subjects showed abnormal anterior superior positivity, starting in the precordial area and proceeding toward the left subclavicular area. The explanation was thought to be the relatively delayed, dysynchronous, and superiorly directed altered sequence of depolarization of the anterior left ventricle. (2) All the subjects showed left lower abnormal negativity. This was thought to represent the unopposed receding activation front after the left ventricular breakthrough posteroinferiorly and also the negative aspect of the abnormally directed superior positivity. (3) Eleven subjects showed abnormal negative potentials at the right lower chest. This was thought to represent the partially unopposed activation fronts of the right ventricular free wall seen after right ventricular epicardial breakthrough, because of the absence of the usually cancelling normal forces from the anterior portion of the left ventricle. Additionally, the surface manifestation of the septal depolarization was found to be indistinguishable from nornal. This study further enhances our understanding of the altered sequence of depolarization in LAFB, as manifested on the body surface instant-by-instant.

Bundle-Branch Block

Integrating human brain maps.

Perception, action, cognition, and emotion can now be mapped in the brain by a growing family of techniques. Positron emission tomography, functional magnetic resonance imaging, event-related electrical potentials, event-related magnetic fields, and other non-invasive imaging techniques are rapidly evolving and providing an increasingly rich literature on the functional organization of the human brain. Although no two techniques map identical physiological processes or physical parameters, replications of functionally specific maps by different techniques indicate sufficient common ground for multimodality integration. The process of integration is multi-tiered. Recent advances in integration range from simple image fusion, to model-based synthetic analyses, to collective databases for neural-system modeling. Spatially, temporally, physiologically, and cognitively accurate computational models of the neural systems of human behavior are the ultimate objective of functional brain mapping. This objective will be reached only through integrating the diversity of modern brain-mapping methods.

Brain Mapping

Problem solving, recall, and mapping relations in isomorphic transfer and nonisomorphic transfer among preschoolers and elementary school children.

Analogical problem-solving processes were studied in 4 experiments using 5- and 7-move scheduling problems. Subjects were preschool and elementary school children. On each acquisition trial, the child heard a list of statements representing the exact series of moves necessary to solve the problem and was immediately asked to recall the list. Physical materials representing the problem were then produced and the child was asked to solve it. In transfer only setting/constraint information was provided prior to problem solving. In the first study, mapping processes were explored in nonisomorphic transfer tasks with different constraints and problem spaces. Mapping processes were very good, except when a feature of the base was mapped to a misleading cue in the transfer problems. The second study revealed that combining the problem-solving task with the recall task facilitated isomorphic transfer but not nonisomorphic transfer. The 2 remaining studies revealed that preschool children show excellent isomorphic transfer in both 5- and 7-move problems. The major developmental difference was in how the children ordered the propositions in their recall protocols. The findings were discussed in terms of problem spaces, flexibility of transfer, and developmental theory.

Child

[Cognitive processes in unconscious patients? A brain mapping study of the P300 potential].

P300 is the most investigated component of the event-related potentials. Being the correlate of an active target discrimination and decision making process it is seen as related to cognition. Such elementary cognitive processes--as expressed in P300--can happen even in states of coma. In four of 35 comatose patients with diffuse head injury we were able to measure the P3-wave showing frontal and parietal components. Accordingly some unawakable patients can still recognize differences in pitch. The structure of components and their psychophysiological meaning are discussed.

Adult

Visual information processing of computed topographic electrical activity brain maps.

Effective display of computer-generated biomedical images draws on computer graphics and image processing, display technology and human factors, visual psychophysics and perception, cognitive psychology, and the new field of scientific data visualization. In converting from raw, acquired data to a visual display, developers need to know the limitations of the data and of the display technology. To obtain reliable inferences about the clinical or physiological state of the patient requires that the computer display be matched to the visual information-processing competence and limitations of human observers. The issues that should be considered by both developers and users of computer-based display technologies to enhance clinical performance in observation and diagnosis are surveyed with reference to electrical activity brain maps.

Brain