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PubMed1986

Sampling-theory analysis of spatial vision.

Spatial-vision research has been largely concerned with measuring and understanding the consequences of receptive-field properties measured by single-unit recording. However, in order to understand spatial-information processing in the visual system, it is equally essential to know the densities and the distribution patterns of the receptive fields. If the receptive fields are not arrayed properly across the visual field, spatial information will be lost. It has been argued, on the basis of the Whittaker-Shannon sampling theorem, that the receptors of the fovea sample the retinal image at a high enough rate to preserve essentially all the available spatial information. In this paper we show how two-dimensional sampling theory can be used to determine which combinations of receptive-field shapes and sampling patterns would preserve all spatial information from the receptors. This analysis will prove useful for determining, in conjunction with electrophysiological and anatomical evidence, what spatial information is or is not being transmitted by a given stage of the visual pathway. It may also prove useful for developing and testing theories of spatial vision.

Humans↗
PubMedDate not supplied

[Comparative analysis of spatial organization of myoglobins. II. Secondary structure].

An analysis of probability of distribution curves of alpha-helical sites and bends of polypeptide chains of myoglobins in half-water mammals (beaver, nutria, muskrat, otter) carried out in comparison with those of myoglobins of the horse and Sperm whale (X-ray diffraction analysis has revealed their tertiary structure) has revealed a coincidence of the secondary structure sites end bends of the chain in the studied respiratory hemoproteins of muscles. Despite a considerable number of amino acid substitutions the profiles of alpha-helicity and B-bends of the compared proteins are practically identical. This indicates to the "resistance" of the probability curves to amino acid substitutions and to retention of the tertiary structure of myoglobins in evolutionary remote species of the animals.

Amino Acid Sequence↗
PubMed2025

Colorectal Liver Metastasis Pathomics Model: Integrating Single-Cell and Spatial Transcriptome Analysis With Pathomics for Predicting Liver Metastasis in Colorectal Cancer.

The liver is the primary target organ for hematologic metastasis of colorectal cancer (CRC), and CRC liver metastasis (CRLM) often precludes radical resection, making it the leading cause of death in patients with CRC. To improve the identification and prediction of liver metastasis risk, we identified a cell type of liver metastasis--triggering malignant cells (LMTMCs) through integrating single-cell RNA sequencing and spatial transcriptome analysis. Multiomics cell communication analysis indicated that the interaction between fibroblasts and LMTMCs through the COL1A1-CD44/SDC4 and LAMA4-CD44 signaling axes could promote CRLM. By applying the one-class logistic regression algorithm, we developed a CRLM scoring system in the bulk RNA-sequencing data according to the abundance of LMTMCs in each individual. Using the grouping labels derived from the CRLM scoring system in the bulk data and the corresponding whole-slide images without any manual annotations at the region or pixel level, processed via slide-level weakly supervised learning, a deep-learning model based on the ResNet18 architecture, called Colorectal Liver Metastasis Pathomics Model, was developed to predict the risk of liver metastasis in patients with CRC. The Colorectal Liver Metastasis Pathomics Model achieved an area under the curve of 0.84 at the internal test set of The Cancer Genome Atlas-CRC histology images. In the external independent validation sets, namely the Affiliated Hospital of Southwest Medical University and the Affiliated Traditional Chinese Medicine Hospital of Southwest Medical University cohorts, the areas under the curve were 0.89 and 0.72, respectively, indicating effective classification performances. This study provided new insights and tools for the early identification of CRLM and demonstrated the potential of combining multiomics with deep learning-based pathomics in cancer research.

Humans↗
PubMed1989

Spatial autocorrelation analysis of the distribution of genotypes within populations of lodgepole pine.

Spatial autocorrelation analyses of point samples within two populations of lodgepole pine (Pinus contorta ssp. latifolia) indicate that single-locus mature tree and pollen genotypes are distributed in a nearly random fashion for most of the allozyme loci assayed. This lack of structure in the distributions of most genotypes is consistent with outcrossing rates that are very nearly 1.0 and with estimates indicating that both pollen and seed are dispersed over long distances in lodgepole pine. However, spatial autocorrelation of genotypes for a few loci suggests that genotypes at these loci may be under natural selection.

Alleles↗
PubMed1986

Spatial resolution analysis of computed tomographic images.

Methods are presented for the quantification of spatial resolution in x-ray computed tomographic (CT) images. Model-dependent methods are derived and compared with model independent methods for computation of the Modulation Transfer Function (MTF). These techniques are applied to phantom images of point, line, edge, and ring discontinuities. The model-dependent methods utilize multiparameter fits of a two-dimensional model function to the image data. Model predictions are compared with results obtained in a model-independent way by numerical transformation of the data. Results of resolution measurements of an Imatron C-100 CT scanner at UCSF and a second experimental scanner at the UCSF Physics Research Laboratory are presented.

Humans↗
PubMed1991

Spatial Fourier analysis of video photobleaching measurements. Principles and optimization.

The major use of the fluorescence recovery after photobleaching (FRAP) technique is to measure the translational motion of the molecular components in various condensed media. In a conventional laser spot photobleaching experiment, a photomultiplier is used to measure the total brightness levels of the bleached region in the sample, so no spatial information can be directly obtained. In video-FRAP, a series of images after photobleaching is acquired, allowing the spatial character of the recovery to be determined; this permits direct detection of both anisotropic diffusion and flow. To utilize all of the available image data to determine the transport coefficients, a two-dimensional spatial Fourier transform analysis of the images after photobleaching was employed. The change in the transform between two time points reflects the action of diffusion during the interim. An important advantage of this method, which involves taking the ratio of image transforms at different time points, is that it does not require a specific initial condition to be created by laser photobleaching. The ability of the analysis to extract transport coefficients from computer-simulated diffusional recovery is assessed in the presence of increasing amounts of noise. Experimental data analysis from the diffusion of proteins in viscous solutions and from the diffusion of protein receptors on cell surfaces demonstrate the feasibility of the Fourier analysis to obtain transport coefficients from the video FRAP measurement.

Biophysical Phenomena↗
PubMed1986

Space and spatial frequency: analysis and representation in the macaque striate cortex.

Simple cells in the macaque striate cortex were tested with bars, edges and gratings. Spatial frequency tuning curves could be predicted from the spatial profiles plotted with bars and edges and the bandwidth could be evaluated more accurately by computing the mean from measured and predicted tuning curves. The results suggest that the mean relative spatial frequency bandwidth (delta f/fo) is nearly constant and of a moderate value. But at each optimal spatial frequency, cells with different bandwidths (about a factor of two) were recorded. The shapes of spatial response profiles resemble the corresponding spatial and spatial frequency characteristics of line and edge detectors evaluated psychophysically. Among the remaining cell types, concentric cells tend to be tuned to lower spatial frequencies and have broader bandwidths, whereas periodic cells prefer higher spatial frequencies and have narrower bandwidths. Thus the mean relative bandwidth tends to decrease significantly with spatial frequency (as required by a system of patch-by-patch Fourier analysis) only when cells with poor orientation selectivity and the non-linear silent periodic cells are included along with the simple cells. Simple cells, on their own, seem to form a quasi-linear contrast processing system which is more biased towards spatial accuracy than spatial frequency selectivity.

Animals↗
PubMed1982

Polarizing microscopy of Picrosirius stained bone sections as a method for analysis of spatial distribution of collagen fibers by optical diffractometry.

Cross sections of femur diaphysis obtained from control and osteopetrotic rats were stained with hematoxylin-eosin (HE) and Picrosirius (SR). Analogous selected areas of bone sections photographed under a polarizing microscope were analysed by optical diffractometry. Since the collagen fibers are a good marker for the structure of bone tissue, their spatial distribution evaluated by optical diffractometry provides information on the tissue architecture. The Picrosirius staining technique enhances the natural birefringency of collagen fibers. Therefore, in the polarizing microscope, pictures of high contrast are obtained. This procedure, by increasing the amount of information in the image, increases the quantity of the data obtained by optical diffractometry in comparison with the HE staining method. The results obtained prove that SR staining combined with polarizing microscopy might be useful for optical diffractometry in analysis of the spatial distribution of collagen fibers in all connective tissues, where they could serve as markers of tissue architecture.

Animals↗
PubMed2025

Spatial transcriptomic analysis of mouse parathyroid gland cells expressing an activating variant of Gcm2.

Glial cells missing 2 (GCM2) is an essential transcription factor for the development of parathyroid glands. Germline GCM2 variants that repress or enhance transcriptional activity predispose a subset of patients to hypoparathyroidism or hyperparathyroidism, respectively. A recurrent germline heterozygous activating missense variant of GCM2, p.Y394S has been identified in some patients with primary hyperparathyroidism. A genetically engineered knock-in mouse model of this variant corresponding to p.Y392S in the mouse Gcm2 gene (Gcm2 +/Y392S) did not show obvious parathyroid tumors. However, in GCM2-binding site mediated luciferase reporter assays in HEK293 cells, the mouse and the human variant both exhibited enhanced transcriptional activity. Therefore, we assessed the effect of this variant on gene expression in vivo in parathyroid glands from Gcm2 +/Y392S and WT mice. Using the 10x Genomics Visium platform, spatially resolved transcriptomic analysis was performed on formalin-fixed and paraffin-embedded (FFPE) tracheal tissue sections of Gcm2 +/Y392S and WT mice to capture RNA from parathyroid glands together with other cell types in the tissue sections. Transcriptome sequence data analysis detected 8 different clusters in the tissue sections based on similarity of gene expression profiles. Cluster-1, which contained parathyroid gland cells expressing Pth and Gcm2, was further evaluated for transcripts that were differentially expressed more than 2-fold in Gcm2 +/Y392S compared to WT. Increased transcript level of Lgals3 (galectin-3) was seen in Gcm2 +/Y392S parathyroid gland cells which is among markers of parathyroid carcinoma. Galectin-3 protein was detected in available FFPE human parathyroid samples of patients with germline heterozygous activating GCM2 variants, p.Y394S (n = 4/10) or p.L379Q (n = 2/2). These results indicate a potential for growth and malignancy of parathyroid glands expressing GCM2 variants. The transcriptomic data of mouse parathyroid gland cells generated in this study can serve as a valuable resource for investigating genes and pathways in normal or abnormal parathyroid gland growth and physiology.

GCM2, gene↗
PubMed1987

Component analysis of spatial and spectral patterns in multispectral images. I. Basis.

A new (to our knowledge) theory of component pattern analysis in multispectral images is developed by using the methods of principal component analysis and nonlinear optimization with a nonnegativity constraint. Given images of a scene in different color bands, we estimate both the spectral curves of components included in the image and the spatial pattern corresponding to each spectral curve. In this method, neither spatial nor spectral features of the components are necessary, but the physical rule of nonnegative absorptivity and density nonnegativity is used for any material of any optical frequency at any position in the image. Experimental results of component analysis with real microscopic image data are shown to demonstrate the effectiveness of the proposed method.

Form Perception↗
PubMed1988

Sex differences in the lateralization of spatial abilities: a spatial component analysis of extreme group scores.

Sex differences in the cerebral lateralization of two discrete components of spatial processing were investigated in high and low ability males and females using the dual-task paradigm. In the first phase of the experiment, the results indicated a pattern of right hemispheric control for a spatial visualization component, regardless of sex and ability level. In the processing of the spatial orientation component of spatial ability, high ability males and females showed left hemispheric lateralization, whereas low ability males and females displayed right hemispheric control. In the second phase of this study, it was observed that high ability females and low ability males may use a verbal mediation strategy in processing spatial visualization tasks. No verbal mediation effects were found for the spatial orientation component.

Adult↗
PubMed1976

High reliability rates of spatial pattern analysis by vectorcardiogram in assessing the severity of eccentric left ventricular hypertrophy.

In 33 patients, including 12 control subjects and 21 with eccentric LVH, LV mass determined by angiocardiogram was correlated to 26 VCG measurements (Frank system) calculated from the scalar X, Y, and Z leads. The results demonstrated that the most reliable indices of VCG in assessing the severity of eccentric LVH determined by angiocardiogram were the magnitude of the spatial mean QRS vector and the time of the spatial maximal QRS vector ("spatial VAT"), of which correlation coefficients were 0.93 and 0.93, respectively. Such high correlation coefficients have never been obtained with the usual ECG analysis. These findings strongly suggest that (1) increased QRS voltage and usual prolonged QRS duration in eccentric LVH are due to an increase in LV mass, and (2) prolonged VAT observed in eccentric LVH is closely related to an anatomic alteration, namely, the greater distance of intra-ventricular conducting pathways as the result of LV dilatation, as an increase in LV mass is usually paralleled by the grade of the chamber enlargement in this type of LVH. Regarding the T loop, correlations between the LV mass and the VCG measurements were less as compared to those of the QRS loop. In general, T changes in moderate or severe LVH may be also related to a certain altered cardiac muscle state, in addition to an increase in LV mass. Angiocardiographic and light microscopic findings of a patient with eccentric LVH in whom a widened QRS-T angle was demonstrated to an extent much more than that expected with an increase in LV mass are presented and discussed. The spatial pattern analysis by VCG is very useful and reliable in assessing the severity of eccentric LVH.

Adolescent↗
PubMed1981

Spatial kinematic analysis of the upper extremity using a biplanar videotaping method.

A biplanar videotaping system is used to generate spatial kinematic data of an upper extremity motion. The technique is based upon the characterization of each segment by four points in three-dimensional space using biplanar videotaping and subsequent analysis by computer-aided descriptive geometry. The tests were conducted to determine the system's accuracy and repeatability. The results of the joint kinematics of the test subjects performing a diagonal reaching activity with and without an orthosis (or an assistive device) are presented.

Biomechanical Phenomena↗
PubMedDate not supplied

[Etiology, occurrence and types of the internal carotid artery loop].

Internal carotid loop was studied in 99 patients out of 1638 cases subjected to angiography. The presence of a loop was arbitrarily accepted when in the tortuous part of the artery one of its segments was situated below the preceding segment. For the spatial analysis of the tortuous part of the artery and its image in the plane of the radiogram a model was used simulating various variants of the course of the internal carotid artery. On the ground of the analysis of the spatial configuration of the arterial loops and the variability of the loop model in the plane of the radiogram six types of the loop were isolated. The loops were found in 9.2% of patients with bilateral angiography and 5.7% of those with unilateral angiography. In adults the loop was present in 5.4% of cases, and in children in 8.9% (statistically significant difference p less than 0.05). It is assumed that the loop in children is a congenital anomaly, while in adulthood besides the congenital etiology an acquired form of the loop is to be taken into account.

Adolescent↗
PubMed1981

Cortical anatomy, size invariance, and spatial frequency analysis.

In a recent application of an algorithm developed in computer and optical pattern recognition, Cavanagh has suggested that a composite of spatial frequency mapping and complex logarithmic mapping would provide translationally, rotationally, and size-invariant mechanism for human vision. In this work, Cavanagh has not made explicit the fact that this transformation is composite, that is, that the first step (global Fourier analysis) perceptually, anatomically, and physiologically inconsistent with primate vision, but that the second step (complex logarithmic mapping) is actually embodied in the anatomy of the primate retinostriate projection. Moreover, it is the complex logarithmic remapping step which is entirely responsible for the computational simplification of the symmetries of size and rotation invariance. These facts, which have been extensively discussed in a recent series of papers, are briefly reviewed and illustrated. Furthermore, it is shown that the architecture of the retinostriate map may provide an example of computational anatomy in vision, such that the spatial representation of a stimulus in the brain may be of direct functional significance to perception, and to the nature of certain visual illusions.

Afterimage↗
PubMed1986

Event-related potentials of the brain and cognitive processes: approaches and applications.

Event-related potentials (ERPs) are recordings of the electric field which the brain produces in fixed time-relation to an event. ERPs open a time and space window onto covert steps of brain information processing which need not be accompanied by overt behavior or private experiences. ERPs are the only noninvasive method which resolves the dynamic pattern of events in the human brain down to the millisecond range. Early ERP components are valuable tools in clinical testing of the afferent sensory systems in the absence of anamnestic or clinical pathology. Later components (e.g. the 'P300') index intermediate, covert steps of information processing and have clarified the time course and the contingencies of processes in attention, decisions and language. ERP waveshapes show electric potential differences between two recording points. Conventional analysis often ignores the fact that there is no unique voltage amplitude or signal latency for a single point, and interprets ambiguous results. Although important insights have emerged with such strategies, full utilization of ERP data requires unambiguous ERP assessment and converging evidence from neuropsychological and cognitive experimentation. Sequences of field distribution maps offer an unbiased display of ERP data. Spatial analysis yields unambiguous values for further comprehensive assessment, and should precede analysis over time. Examples of spatial analysis have shown that different ERP field configurations follow the presentation of noun and verb meaning of homophone words; that the ERP effects to subjective contours resemble those to attention in time course and topography; that the 'cognitive' P300 component reflects the specific stimulus location; and that subliminal information influences the configuration of late ERP fields.

Attention↗