SEARCH · PubMed Health

Results for “Visualized analysis”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,063 records · Page 59Linked to original sources

PubMed2001

Cortical correlates of gesture processing: clues to the cerebral mechanisms underlying apraxia during the imitation of meaningless gestures.

The clinical test of imitation of meaningless gestures is highly sensitive in revealing limb apraxia after dominant left brain damage. To relate lesion locations in apraxic patients to functional brain activation and to reveal the neuronal network subserving gesture representation, repeated H2(15O)-PET measurements were made in seven healthy subjects during a gesture discrimination task. Observing paired images of either meaningless hand or meaningless finger gestures, subjects had to indicate whether they were identical or different. As a control condition subjects simply had to indicate whether two portrayed persons were identical or not. Brain activity during the discrimination of hand gestures was strongly lateralized to the left hemisphere, a prominent peak activation being localized within the inferior parietal cortex (BA40). The discrimination of finger gestures induced a more symmetrical activation and rCBF peaks in the right intraparietal sulcus and in medial visual association areas (BA18/19). Two additional foci of prominent rCBF increase were found. One focus was located at the left lateral occipitotemporal junction (BA 19/37) and was related to both tasks; the other in the pre-SMA was particularly related to hand gestures. The pattern of task-dependent activation corresponds closely to the predictions made from the clinical findings, and underlines the left brain dominance for meaningless hand gestures and the critical involvement of the parietal cortex. The lateral visual association areas appear to support first stages of gesture representation, and the parietal cortex is part of the dorsal action stream. Finger gestures may require in addition precise visual analysis and spatial attention enabled by occipital and right intraparietal activity. Pre-SMA activity during the perception of hand gestures may reflect engagement of a network that is intimately related to gesture execution.

Adult↗

PubMed2006

Multidimensional shape similarity in the development of visual object classification.

The current work examined age differences in the classification of novel object images that vary in continuous dimensions of structural shape. The structural dimensions employed are two that share a privileged status in the visual analysis and representation of objects: the shape of discrete prominent parts and the attachment positions of those parts. Experiment 1 involved a triad classification task in which participants at each of three different ages (5 years, 8 years, and adult) classified object images from two distinct stimulus sets. Across both sets, the youngest children demonstrated a systematic bias toward the shape of discrete parts during their judgments. With increasing age, participants increasingly came to select both the shape and the position of parts when classifying the images. The findings from Experiment 2 indicate that the local shape bias observed in young children's classifications is not merely a consequence of a discrimination advantage for that dimension. Results are discussed in relation to corresponding age-related changes in other functional contexts of visual processing.

Adult↗

PubMed1995

Computer-assisted pathology of intraepithelial adenocarcinoma and related lesions: 3-D distribution, structural aberration and discrimination.

To discriminate among intraepithelial neoplasms, we have been relying on tissue microscopy, but pathologists' subjectivity sometimes impairs diagnosis. Even an individual pathologist is sometimes unable to reproduce exactly his or her own previous diagnosis. Are various atypical lesions classifiable in a reproducible way, and if they are, how? The reliability of a diagnosis will be strengthened if we can define the "natural" categories inherent in cells and tissues. Morphometry and statistical analysis using a computer can provide answers. Atypia, a morphological feature of carcinoma, is essentially multivariate. Quantification of a tissue feature requires reducing it to a set of ten or more quantities, including size, shape and position of the nucleus, nucleolus, and the cell itself. The grade of aberration from the norm can be assessed only by a synthetic approach, using a computer for multivariate cluster analysis. This classification has been attempted in adenocarcinoma and related lesions of the lung and pancreas. The categories thus established are reproducible, because the lesions fall into divisions according to their forms. We can also examine the organ distribution of intraepithelial neoplasms by three dimensional (3-D) computer-assisted mapping. To reach a higher level of reliability, as many meaningful features as possible should be taken into account. Particularly, we emphasize the significance of architectural pattern as a biomarker for intraepithelial glandular neoplasms. Computer-aided 3-D structural analysis visualizes the basic skeleton of these neoplasms around which the cells adhere. Instead of the dichotomous tree pattern of normal glands, the tumors basically harbor a 3-D network, tubular or porous, which increasingly deviates from the norm along with the transition from adenoma to well to moderately to poorly differentiated adenocarcinoma. This structural aberration, if recognizable on 2-D sectional images, will serve as a surrogate endpoint biomarker for glandular tumors.

Algorithms↗

PubMed2006

Independent component analysis-motivated approach to classificatory decomposition of cortical evoked potentials.

BACKGROUND: Independent Component Analysis (ICA) proves to be useful in the analysis of neural activity, as it allows for identification of distinct sources of activity. Applied to measurements registered in a controlled setting and under exposure to an external stimulus, it can facilitate analysis of the impact of the stimulus on those sources. The link between the stimulus and a given source can be verified by a classifier that is able to "predict" the condition a given signal was registered under, solely based on the components. However, the ICA's assumption about statistical independence of sources is often unrealistic and turns out to be insufficient to build an accurate classifier. Therefore, we propose to utilize a novel method, based on hybridization of ICA, multi-objective evolutionary algorithms (MOEA), and rough sets (RS), that attempts to improve the effectiveness of signal decomposition techniques by providing them with "classification-awareness." RESULTS: The preliminary results described here are very promising and further investigation of other MOEAs and/or RS-based classification accuracy measures should be pursued. Even a quick visual analysis of those results can provide an interesting insight into the problem of neural activity analysis. CONCLUSION: We present a methodology of classificatory decomposition of signals. One of the main advantages of our approach is the fact that rather than solely relying on often unrealistic assumptions about statistical independence of sources, components are generated in the light of a underlying classification problem itself.

Algorithms↗

PubMed1998

Synaptic and neurochemical characterization of parallel pathways to the cytochrome oxidase blobs of primate visual cortex.

The primary visual cortex (V1) of primates is unique in that it is both the recipient of visual signals, arriving via parallel pathways (magnocellular [M], parvocellular [P], and koniocellular [K]) from the thalamus, and the source of several output streams to higher order visual areas. Within this scheme, output compartments of V1, such as the cytochrome oxidase (CO) rich blobs in cortical layer III, synthesize new output pathways appropriate for the next steps in visual analysis. Our chief aim in this study was to examine and compare the synaptic arrangements and neurochemistry of elements involving direct lateral geniculate nucleus (LGN) input from the K pathway with those involving indirect LGN input from the M and P pathways arriving from cortical layer IV. Geniculocortical K axons were labeled via iontophoretic injections of wheat germ agglutinin-horseradish peroxidase into the LGN and intracortical layer IV axons (indirect P and M pathways to the CO-blobs) were labeled by iontophoretic injections of Phaseolus vulgaris leucoagglutinin into layer IV. The neurochemical content of both pre- and postsynaptic profiles was identified by postembedding immunocytochemistry for gamma-amino butyric acid (GABA) and glutamate. Sizes of pre- and postsynaptic elements were quantified by using an image analysis system, BioQuant IV. Our chief finding is that K LGN axons and layer IV axons (indirect input from M and P pathways) exhibit different synaptic relationships to CO blob cells. Specifically, our results show that within the CO blobs: 1) all K cell axons contain glutamate, and the vast majority of layer IV axons contain glutamate with only 5% containing GABA; 2) K axons terminate mainly on dendritic spines of glutamatergic cells, while layer IV axons terminate mainly on dendritic shafts of glutamatergic cells; 3) K axons have larger boutons and contact larger postsynaptic dendrites, which suggests that they synapse closer to the cell body within the CO blobs than do layer IV axons. Taken together, these results suggest that each input pathway to the CO blobs uses a different strategy to contribute to the processing of visual information within these compartments.

Animals↗

PubMed2005

Assessment of left ventricular contraction by parametric analysis of main motion (PAMM): theory and application for echocardiography.

The computerized study of the regional contraction of the left ventricle has undergone numerous developments, particularly in relation to echocardiography. A new method, parametric analysis of main motion (PAMM), is proposed in order to synthesize the information contained in a cine loop of images in parametric images. PAMM determines, for the intensity variation time curves (IVTC) observed in each pixel, two amplitude coefficients characterizing the continuous component and the alternating component; the variable component is generated from a mother curve by introducing a time shift coefficient and a scale coefficient. Two approaches, a PAMM data driven and a PAMM model driven (simpler and faster), are proposed. On the basis of the four coefficients, an amplitude image and an image of mean contraction time are synthesized and interpreted by a cardiologist. In all cases, both PAMM methods allow better IVTC adjustment than the other methods of parametric imaging used in echocardiography. A preliminary database comprising 70 segments is scored and compared with the visual analysis, taken from a consensus of two expert interpreters. The levels of absolute and relative concordance are 79% and 97%. PAMM model driven is a promising method for the rapid detection of abnormalities in left ventricle contraction.

Algorithms↗

PubMed2006

Determination of visual figure and ground in dynamically deforming shapes.

Figure/ground assignment - determining which part of the visual image is foreground and which background - is a critical step in early visual analysis, upon which much later processing depends. Previous research on the assignment of figure and ground to opposing sides of a contour has almost exclusively involved static geometric factors - such as convexity, symmetry, and size - in non-moving images. Here, we introduce a new class of cue to figural assignment based on the motion of dynamically deforming contours. Subjects viewing an animated, deforming shape tended to assign figure and ground so that articulating curvature extrema - i.e., "hinging" vertices - had negative (concave) contour curvature. This articulating-concavity bias is present when all known static cues to figure/ground are absent or neutral in each of the individual frames of the animation, and even seems to override a number of well-known static cues when they are in opposition to the motion cue. We propose that the phenomenon reflects the visual system's inbuilt expectations about the way shapes will deform - specifically, that deformations tend to involve rigid parts articulating at concavities.

Cues↗

PubMed2002

Human neural systems for face recognition and social communication.

Face perception is mediated by a distributed neural system in humans that consists of multiple, bilateral regions. The functional organization of this system embodies a distinction between the representation of invariant aspects of faces, which is the basis for recognizing individuals, and the representation of changeable aspects, such as eye gaze, expression, and lip movement, which underlies the perception of information that facilitates social communication. The system also has a hierarchical organization. A core system, consisting of occipitotemporal regions in extrastriate visual cortex, mediates the visual analysis of faces. An extended system consists of regions from neural systems for other cognitive functions that can act in concert with the core system to extract meaning from faces. Of regions in the extended system for face perception, the amygdala plays a central role in processing the social relevance of information gleaned from faces, particularly when that information may signal a potential threat.

Attention↗

PubMed2005

[The role of videoelectroencephalography in diagnostics of seizures in neonates and infants].

OBJECTIVES: The clinical characteristic of attack is frequently difficult to unequivocal establishment by observation. It refers especially to seizures in youngest children, due to complicated attack morphology. VideoEEG as a diagnostic tool makes possible more precise establishment of seizures type and derivation. THE AIM: The aim of this analysis was to establish an importance of videoEEG for the differentiation of epileptic and non-epileptic attacks in neonates and youngest infants. MATERIALS: 20 children, 10 girls and 10 boys from the Neurological Division, the Neonatal Intensive Care Unit, the Intensive Care Unit, and the Division of Cardiology, admitted for examination between the 2000 and 2004 years in the Lab of Clinical Electrophysiology of the Department of Pediatric Neurology were included. The age of children, including 7 neonates, was at the moment of examination between 3 and 10 weeks. The first attack occurred between the first day of life and 7th week. In 15/20 of children features of encephalopathy were present. METHODS: The videoEEG recordings were provided in identical conditions, including place and personnel as well, using apparatus PL. 270 video option MedtronicDantec and camera Samsung with movable focus. The visual analysis was provided by two licensed in electrophysiology physicians and results were averaged. RESULTS: In 15/20 children clinical attacks were registered, including stereotypical seizures in 7 children and polimorphic seizures in 8 children. The most frequent attacks were apneic (11/ 20) and the registered seizures were generalised tonic (6/20) and focal (5/ 20). In 5 children attacks were not registered during examinations. In 2 children of this group the bioelectrical activity was also unchanged, whereas in 3 children the significant pathology was detected. Among 15 children with registered in videoEEG attacks, in 9 children ictal discharges were recorded, in 2 children burst-suppression discharges and in the remaining 4 children ictal changes of bioelectrical activity were not recorded. Interictal activity similar to ictal was detected in 2 children with burst-suppression discharges only, and in other cases it was differentiated. 2 of 4 children without discharges during attacks had also normal interictal activity, whereas in the remaining 2 children the immature low voltage flat activity was recorded. Among 9 children with ictal discharges, in 5 children interictal discharges were detected as well, whereas in 2 children only low-voltage activity with pathological features of sleep was detected, but in 2 children interictal activity was normal. The results of videoEEG and other tests allowed to recognized nn epileptic attacks in 5 children, probably epileptic in 1, epileptic seizures in 8 and epilepsy with genetic and hypoxic-ischaemic disorders in 6 children. CONCLUSION: The videoEEG allowed to register clinical seizures in the majority of youngest children with paroxysmal events, contributing to the diagnosis of tonic and polimorphic seizures and to the correct classification of apnoea. In 25% of children with and without registered clinical attacks, this examination allowed to diagnose non-epileptic attacks. To establish epilepsy, the ictal changes of bioelectrical activity were important and interictal as well.

Brain↗

PubMed2003

3DNA: a software package for the analysis, rebuilding and visualization of three-dimensional nucleic acid structures.

We present a comprehensive software package, 3DNA, for the analysis, reconstruction and visualization of three-dimensional nucleic acid structures. Starting from a coordinate file in Protein Data Bank (PDB) format, 3DNA can handle antiparallel and parallel double helices, single-stranded structures, triplexes, quadruplexes and other complex tertiary folding motifs found in both DNA and RNA structures. The analysis routines identify and categorize all base interactions and classify the double helical character of appropriate base pair steps. The program makes use of a recently recommended reference frame for the description of nucleic acid base pair geometry and a rigorous matrix-based scheme to calculate local conformational parameters and rebuild the structure from these parameters. The rebuilding routines produce rectangular block representations of nucleic acids as well as full atomic models with the sugar-phosphate backbone and publication quality 'standardized' base stacking diagrams. Utilities are provided to locate the base pairs and helical regions in a structure and to reorient structures for effective visualization. Regular helical models based on X-ray diffraction measurements of various repeating sequences can also be generated within the program.

Base Pairing↗

PubMed1989

Selective impairment of visual motion interpretation following lesions of the right occipito-parietal area in humans.

A group of eighteen patients selected on the basis of the anatomical locus of the lesion, normal visual acuity and the ability to discriminate visual motion, were assessed on the perception of Julesz Random-Dot stereograms and on three tasks of visual motion interpretation: Speed Discrimination, 3D-Structure-from-Motion and 2D-Form-from-motion. The results on these experimental tasks demonstrate a double dissociation of deficits on the visual analysis of motion and stereopsis in the patients with lesions to the posterior right hemisphere. The right occipital-parietal (ROP) group failed on the Stereopsis task and showed a dramatic impairment on the Speed Comparison and on the Structure-from-Motion experiments. They performed in the normal range, however, on the 2D-Form-from-Motion task. The right occipital-temporal (ROT) group, on the other hand, were severely impaired on the identification of two dimensional forms from motion or stereopsis. In both cases, however, they were able to obtain a coarse segregation of the figure from the background. The ROT group did not present significant deficits on the Speed Discrimination and the Structure-from-Motion tasks. The results are discussed in the light of recent physiological and psychophysical findings, and it is hypothesized that, in the human brain, visual deficits of motion interpretation and of stereopsis are associated with right occipital-parietal lesions.

Adult↗

PubMed2005

A common neural basis for receptive and expressive communication of pleasant facial affect.

There is accumulating evidence suggesting that the visual representation of facial affect is closely linked to its motor representation. To examine whether perception of pleasant facial affect involves neural circuitries associated with its production, we performed an fMRI experiment with 'compressed image acquisition' where subjects smiled and observed movies depicting other people smiling within scan-free time intervals between the acquisition of each image volume. Overlaps between the brain activation during observation and execution of smile expressions were located in the right premotor cortex and pars opercularis of the inferior frontal gyrus, right parietal operculum (SII) and left anterior insula. Observation of smile expressions further yielded signal increases within the posterior superior temporal sulcus (STS), fusiform gyrus and ventral amygdala. The results show that perceiving and expressing pleasant facial affect share a common neural basis in areas concerned with motor as well as somato- and limbic-sensory processing. In concert with temporal regions serving the visual analysis of facial expressive features, a mapping of the observed expressions onto neural circuitries associated with the production of these expressions and its somatosensory consequences could provide a description of what the expression would feel like if produced in the observer. Such a mechanism is suggested to be important for empathic understanding of others' feelings.

Adult↗

PubMed1976

Striate cortex potentials related to eye movements in the light and in darkness in the waking human.

Potentials in relation to eye movements were studied by means of direct recording of the striate cortex in a waking man. In a lighted environment, the usual evoked potential--lambda response--was obtained and was clearly visible after each eye movement. In complete darkness no individual potential was observable by means of visual analysis after each eye movement, but a slow potential of low amplitude could be obtained by superimposition and averaging of the cortical striate activity time-locked to the start of a series of eye movements. This eye-movement potential showed a longer latency and a lower amplitude than the lambda response. These data are discussed in reference to those obtained in the cat and the monkey; the significance of this eye-movement potential in darkness as a 'corollary discharge' is considered.

Darkness↗

PubMed2001

Different uptake of 99mTc-ECD adn 99mTc-HMPAO in the same brains: analysis by statistical parametric mapping.

The purpose of this study was to investigate the differences between technetium-99m ethyl cysteinate dimer (99mTc-ECD) and technetium-99m hexamethylpropylene amine oxime (99mTc-HMPAO) uptake in the same brains by means of statistical parametric mapping (SPM) analysis. We examined 20 patients (9 male, 11 female, mean age 62+/-12 years) using 99mTc-ECD and 99mTc-HMPAO single-photon emission tomography (SPET) and magnetic resonance imaging (MRI) of the brain less than 7 days after onset of stroke. MRI showed no cortical infarctions. Infarctions in the pons (6 patients) and medulla (1), ischaemic periventricular white matter lesions (13) and lacunar infarction (7) were found on MRI. Split-dose and sequential SPET techniques were used for 99mTc-ECD and 99mTc-HMPAO brain SPET, without repositioning of the patient. All of the SPET images were spatially transformed to standard space, smoothed and globally normalized. The differences between the 99mTc-ECD and 99mTc-HMPAO SPET images were statistically analysed using statistical parametric mapping (SPM) 96 software. The difference between two groups was considered significant at a threshold of uncorrected P values less than 0.01. Visual analysis showed no hypoperfused areas on either 99mTc-ECD or 99mTc-HMPAO SPET images. SPM analysis revealed significantly different uptake of 99mTc-ECD and 99mTc-HMPAO in the same brains. On the 99mTc-ECD SPET images, relatively higher uptake was observed in the frontal, parietal and occipital lobes, in the left superior temporal lobe and in the superior region of the cerebellum. On the 99mTc-HMPAO SPET images, relatively higher uptake was observed in the medial temporal lobes, thalami, periventricular white matter and brain stem. These differences in uptake of the two tracers in the same brains on SPM analysis suggest that interpretation of cerebral perfusion is possible using SPET with 99mTc-ECD and 99mTc-HMPAO.

Adult↗

PubMed1983

Binocular rivalry and semantic processing: out of sight, out of mind.

Previous studies of binocular rivalry have shown that some aspects of a phenomenally suppressed stimulus remain available for visual analysis. The question remains, however, whether this analysis extends to the case of semantic information. This experiment examines that question using a semantic-priming paradigm in which prime words were briefly flashed to an eye during either dominance or suppression phases of binocular rivalry. Reaction times on a lexical-decision task were significantly shortened (the semantic-priming effect) only when prime words were presented to an eye during dominance; suppression acted to impair word recognition and to eliminate semantic priming. These results are inconsistent with certain cognitive models of binocular rivalry.

Cognition↗

PubMedDate not supplied

[Visual and mathematical analysis of background cerebral bioelectric activity in cases of vascular headache (a question of rhythmicity)].

The visual and mathematical analysis (computer assisted) of the background cerebral activity in patients with vasomotor headaches, including common vasomotor headaches, Horton's headache and migrainous headache showed statistically significant fluctuations of the frequency of the background cerebral bioelectric activity only in patients with migrainous headaches. Of interest was the observed evident asymmetry of the alpha rhythm frequency. This indicates that the background bioelectric cerebral activity is arrhythmic and asymmetrical in patients with migrainous headaches.

Adult↗

PubMed1986

The objective evaluation of the phase image: a comparison of different automated methods.

One hundred and twenty eight patients with suspected or proven CAD were investigated using both X-ray ventriculography and equilibrium gated radionuclide angiography. In order to diagnose regional wall motion abnormalities, the parametric images obtained by Fourier analysis of the radionuclide images were analysed by different automated methods based on the measurement of the homogeneity of the phase values within the LV ROI. The effect of a diastolic frames exclusion, smoothing the original data, weighting the phase histogram, using Bacharach's error corrected phase distribution functions, using different descriptors of the spread of the phase histograms or distribution functions were tested. Using the results of the X-ray examination as the gold standard, ROC curves were plotted for each method. The ROC curves were modelled by a binormal model using the maximum likelihood method. Statistical tests were applied on the area under the ROC curves. The results show that the diagnostic value of the automated methods depends mainly on the way the histograms or distribution functions are described and to a lesser extent on the type of histograms or distribution functions used. The best result is obtained after smoothing, diastolic frames exclusion, weighting the phase histogram by the amplitude and describing it by its standard deviation. Nevertheless, this result is not significantly different from the result obtained by visual analysis of the phase and amplitude images.

Adult↗

PubMed1998

A visual method for analysing bucco-lingual position of artificial posterior teeth. Part 1: use of the ridge crest.

We have developed a visual analysis method to examine the spatial relationship between the edentulous ridges and the bucco-lingual position of the artificial posterior teeth in complete denture fabrication. In this system, a non-contact type shape measurement system is used. We applied this system to the plaster models and the wax dentures of an edentulous patient. Using the measurement data on the upper and lower plaster models, we reconstructed their shape three-dimensionally and determined the points regarded as the ridge crests and the inter-alveolar crest lines in the frontal sections. To generate the upper and lower ridge crest lines which consisted of the points of the ridge crests, interpolation by B-spline curves was applied. Furthermore, the loft surfaces that we regarded as the consecutive inter-alveolar crest lines, were generated between the upper and lower ridge crest lines. The surface models of the plaster models and artificial teeth were displayed on the cathode-ray tube display unit, and the ridge crest lines and the consecutive inter-alveolar crest lines were superimposed on the surface models. This method could be utilized to visualize and examine the bucco-lingual position of the artificial posterior teeth in reference to the inter-alveolar crest lines.

Computer Graphics↗