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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↗

PubMed1991

Pattern of epithelial cell cycling in hydra.

We have investigated the spatial pattern of epithelial cell cycling in a mutant strain of Hydra magnipapillata (sf-1). This strain has temperature sensitive interstitial stem cells and thus polyps containing only epithelial cells can be obtained by growth at the restrictive temperature. Epithelial animals were pulse labeled with the thymidine analog 5'-bromo-2'-deoxyuridine (Brdu) and stained with anti-Brdu antibody to visualize S phase cells. Our results indicate that Brdu-labeled cells are broadly and fairly evenly distributed along the body column. Feeding stimulates a rapid decrease and then an increase in labeled cells in gastric tissue; labeled cells in the head are not affected. Starvation leads to a twofold decrease in labeled cells in the gastric region; the density of labeled cells in head tissue remains similar to that in well-fed animals. During bud formation the number of labeled epithelial cells increases significantly in the evaginating bud. During head regeneration the number of labeled cells declines sharply during the first 12 hr and then increases to a density typical of head tissue by 24-36 hr of regeneration. The results indicate the release of signals by feeding and regeneration which inhibit mitosis. By contrast head tissue and developing buds express signals stimulating mitosis. Thus changes in epithelial cell cycling in hydra are closely correlated with morphogenetic events as well as with feeding stimuli.

Animals↗

PubMed1989

Wavelike isomorphic prepatterns in development.

The patterns generated by these mechanisms are usually wavelike spatial patterns in the distribution of the chemical components and/or physical properties of the organism or tissue being considered. In this paper the range of patterns generated by one of these mechanisms, namely the reaction-diffusion (RD) system (Turing, 1952), is reviewed and its potential to function as a source of isomorphic prepatterns for the regulation of development in a wide range of organisms is illustrated. Examples have been chosen to show the capacity of an RD system to generate a single stationary spatial prepattern, as well as a travelling wavelike spatial prepattern. However, the full potential of an RD system to regulate development stems from its capacity to spontaneously generate a temporal sequence of isomorphic stationary wavelike spatial prepatterns, rather than just a single isomorphic stationary spatial prepattern. To demonstrate this point the examples presented include the morphogenesis of the skin and some of its appendages, as well as the early decisions in the embryogenesis of Drosophila leading to segmentation. The mini-review begins by comparing the concepts of positional information and a temporal sequence of isomorphic prepatterns, which represent two quite different approaches to understanding the spatial and temporal regulation of cellular differentiation.

Animals↗

PubMed1974

Responses of olfactory bulb neurones to odour stimulation of small nasal areas in the salamander.

1. Previous experiments have suggested that one way odours may be discriminated is by different spatial patterns of response at both the olfactory bulb and receptor level. The present experiments were designed to test to what extent the position of an odour on the receptor mucosa can influence the activity of olfactory bulb neurones.2. To deliver odours to small areas on the nasal receptor sheet a new method for local application of odour was developed. The flow rate, concentration, and time course of the odour were controlled using the olfactometer described in the preceding paper.3. In thirty olfactory bulb units in the salamander it was found that if the response of a unit to odour delivered to the entire exposed receptor epithelium were suppression (type S), then the unit tended to be suppressed when odour was delivered to a number of localized epithelial regions. If the response were excitation (type E) to stimulation of the entire epithelium, then stimulation to only one or two localized regions would elicit the maximum response.4. Different epithelial regions had the ability to cause excitation in the same bulbar unit depending on the odour being used. Two odours, camphor and amyl acetate, elicited maximum excitation when they were presented to different mucosal areas. The areas at which presentation of these odours gave excitation were surprisingly consistent from unit to unit and animal to animal.5. The data presented here suggest the presence of restricted excitatory receptive fields for some olfactory bulb neurones for a particular odour.6. The presence of spatial response patterns using odour delivery to small nasal receptor regions and thus the presence of receptive fields is discussed with reference to bulbar neuronal circuitry.

Action Potentials↗

PubMed1985

Metabolic labeling associated with index finger stimulation in monkey SI: between animal variability.

Four monkeys (Macaca fascicularis) were stimulated with an identical intermittent vertical displacement (flutter) stimulus on the tip of the index finger and received intravenous [14C]2-deoxyglucose (2-DG). The majority of metabolic labeling was found to exist in areas 3b and 1 of the anterior parietal cortex (SI) in the form of intermittent patches, which extended vertically across the cortical laminae. When the patches were traced through adjacent sections and reconstructed to produce a 2-dimensional map, it became evident that the patches of label combined to form a complex spatial pattern consisting of strips. Although the flutter stimulus was applied to a spatially restricted peripheral field, the metabolic pattern was always complex and widely distributed within SI. Nevertheless, the 2-DG patterns produced in the different animals stimulated with the same stimulus were strikingly similar. The relationships between descriptions of the SI index finger representation based on neurophysiological mapping data and the distribution of 2-DG uptake are described. The reproducibility of the 2-DG labeling pattern and relationship to neurophysiological maps suggests that the 2-DG mapping method provides a potent and useful tool for the investigation of stimulus representation in the somatosensory cortex.

Animals↗

PubMed1989

Dopamine D1 receptor development in the rat striatum: early localization in striosomes.

The development of dopamine D1-receptors in rat striatum during the early postnatal period is examined, using autoradiography and [3H]SCH 23390 as ligand. Dopamine D1-receptors are present in striatum at birth and are more dense than in any adjacent region. The receptors are preferentially localized in striosomes and to some extent in a subcallosal streak. The density of D1-receptors in the matrix increases with age so that by two weeks postnatally the striosomal pattern is no longer evident, and the overall dense labelling is the same as seen in adults. Dopamine D1-receptor development seems to take place earlier than that of dopamine terminals but at the same time as or somewhat later than that of acetylcholinesterase. The D1-defined striosomes move from ventrolateral towards dorso-medial striatum with increasing age and from anterior to posterior striatum. This direction is nearly perpendicular to the direction of development of several other markers, including dopamine terminals and D2-receptors. The present studies indicate that for markers appearing in the striosomal compartment there are different patterns of development with respect to time and spatial pattern. Regulation of striatal development by interaction of neuronal systems with one another and with other factors is complex and will require extensive study to clarify the mechanisms involved.

Aging↗

PubMed1994

Expression of the inducible form of nitric oxide synthase by reactive astrocytes after transient global ischemia.

We recently demonstrated that reactive astrocytes express NADPH diaphorase activity, a marker for Nitric Oxide Synthase, following transient global ischemia (Neuroscience Letters 154: 125-128). There has been little evidence that astrocytes express Nitric Oxide Synthase or produce NO (nitric oxide) in vivo; although in vitro experiments have shown that cultured astrocytes can produce NO. To determine whether reactive astrocytes express inducible form of NOS (iNOS) in vivo, we studied the pathological changes of rat hippocampus by immunohistochemistry after 10 minutes of transient global ischemia, which results in the selective delayed death of CA1 pyramidal cells and marked gliosis in the CA1 subfield. In the normal hippocampus, astrocytes express neither NADPH diaphorase activity nor iNOS. After ischemia, the temporal and spatial pattern of iNOS, NADPH diaphorase, and GFAP are very similar, indicating that reactive astrocytes express iNOS. Double staining for NADPH diaphorase and GFAP, or iNOS and GFAP confirmed that reactive astrocytes express both NADPH diaphorase activity and iNOS immunoreactivity. These changes were observed three day after ischemia and increased in prominence from one week to one month. The staining pattern of OX42, an antibody that recognizes both microglia and macrophages, is spatially and temporally distinct from the pattern of NADPH diaphorase and iNOS staining. Thus, we conclude that transient global ischemia induces iNOS primarily in reactive astrocytes. This increase in NOS expression and, presumably, NO production by reactive astrocytes may play a role in the process of delayed neuronal death or in the remodeling responses that occur after ischemic damage.

Amino Acid Oxidoreductases↗

PubMed1989

Tactile sensing of surface features.

The tactile recognition of an object held in the hand involves characterizing its surface features. Recent neurophysiological studies point to a number of possible ways in which tactile primary afferents convey information about surface characteristics. The spatial pattern of the afferents that are activated probably underlies the unique recognition of patterns. Measures of afferent response intensity correlate well with overall surface texture and quantitatively encode variations in surface spatial parameters. The temporal patterns of afferent firing provide yet another potential mechanism by which surface features are signaled. Studies of somatosensory cortex have already begun to examine the central processing of these afferent signals, and this remains a fertile field for the future.

Afferent Pathways↗

PubMed1995

Analysis of DNA diversity by spatial autocorrelation.

Two statistics are proposed for summarizing spatial patterns of DNA diversity. These autocorrelation indices for DNA analysis, or AIDAs, can be applied to RFLP and sequence data; the resulting set of autocorrelation coefficients, or correlogram, measures whether, and to what extent, individual DNA sequences or haplotypes resemble the haplotypes sampled at arbitrarily chosen spatial distances. Analyses of computer-generated sets of data, and of RFLP data from two natural populations, show that AIDAs allow one to objectively and simply identify basic patterns in the spatial distribution of haplotypes. These statistics, therefore, seem to be a useful tool both to explore the genetic structure of a population and to suggest hypotheses on the evolutionary processes that shaped the observed patterns.

DNA↗

PubMed1991

Spatial and temporal patterning distinguishes the locomotor activating effects of dizocilpine and phencyclidine in rats.

A behavioral pattern monitor was used to assess the effects of dizocilpine (MK-801) and phencyclidine on the spatial and temporal patterns of locomotion and investigatory behavior in rats. The monitor provided both quantitative measures of crossovers, rearings and holepokes and qualitative measurement of the spatial and temporal patterns of locomotion. Dizocilpine (0.004-0.5 mg/kg) and phencyclidine (0.25-5.0 mg/kg) produced similar, dose-dependent increases in locomotor activity. At small doses, dizocilpine and phencyclidine increased investigatory holepokes, while at larger doses, both drugs significantly decreased the number of holepokes. Rearings were reduced similarly by the larger doses of each drug. Both dizocilpine and phencyclidine produced perseverative spatial patterns of locomotion, especially at larger doses. However, the locomotor patterns produced by these drugs were found to be dissimilar in spatial quality. After phencyclidine, animals frequently circled the perimeter of the monitor chamber or moved repetitively in horseshoe or figure-8 patterns. By contrast, rats given dizocilpine completed small rotations about either end of the chamber. Pretreatment with a small dose (0.02 mg/kg) of haloperidol, prior to either dizocilpine (0.5 mg/kg) or phencyclidine (5.0 mg/kg) had no effect on the increase in locomotor activity or the decreases in investigatory holepokes produced by the drugs. However, haloperidol altered the effects of phencyclidine on the spatial and temporal patterns of locomotion, suggesting that sigma receptors or other haloperidol-sensitive binding sites, may influence the quality but not the quantity of phencyclidine-induced hyperactivity.

Animals↗

PubMed1992

Spatial low frequency pattern analysis in positron emission tomography: a study between normals and schizophrenics.

Using the two-dimensional Fourier transform and the brain's centroidal principal axis, a method is developed for the analysis of PET metabolic brain images without the use of predefined anatomic regions of interest. We applied the method to images from a group of 11 normal and 12 medicated schizophrenics tested under resting conditions and under a visual task. A cortical/subcortical spatial pattern was found to be significant in two directions; anterior/posterior and chiasmatic (left-anterior/right-posterior). The best individual clinical classification (Jackknife classification) occurred under visual task at two axial brain levels: at the basal ganglia with correct classification rates of 91% and 84%, while the cerebellum had rates of 82% and 92%. These high classification rates were obtained using only the four coefficients of the lowest spatial frequency. These results point to the generalized brain dysfunction of regional glucose metabolism in chronic medicated schizophrenics both at rest and at a visual image-tracking task.

Analysis of Variance↗

PubMed1986

Source density analysis of scalp potentials during linguistic and non-linguistic processing of visual stimuli.

Event-related potentials (ERPs) were recorded from 40 locations, covering most of the scalp, during repeated tasks in which the observer (O) had to judge either the tense of a printed verb (V) or the symmetry of a spatial pattern (S). Stimuli were drawn at random from large ensembles. A simplified method of Laplacean analysis (MacKay 1983, 1984) allowed the corresponding source densities to be mapped at up to 28 locations, relatively free of artefacts due to eye movements or tongue movements. O signalled his judgement in each case by pressing one of two buttons on a given cue. The decision time allowed was kept short (about 1 s) but long enough for the task to be handled successfully. When stimuli 'V' and 'S' were drawn from geometrically different ensembles, the source-density distributions for the two tasks differed significantly at a number of locations. When 'V' and 'S' were drawn from a common ensemble, however, and O was instructed on each trial (in random order) to assess each stimulus as a word or as a geometrical pattern, the similarities in the source-density maps were more striking than the differences. It would seem that during sufficiently rapid verbal and spatial judgments, little sign of hemispheric specialization or task-specific differences may appear in the spatiotemporal profile of ERP source densities. More salient differences, some lateralized, appeared during the preparation interval prior to verbal and spatial tasks; but their pattern varied widely from subject to subject.

Cerebral Cortex↗

PubMed1987

MPTP produces a mosaic-like pattern of terminal degeneration in the caudate nucleus of dog.

This paper describes the spatial pattern of terminal degeneration in the caudate nucleus and putamen of the dog following an injection of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Marked inhomogeneities in the filed of terminal degeneration were found in the head of the caudate nucleus, which are reminiscent of the fundamental patch/matrix organization of the striatum. Using MPTP as a selective lesioning method, our results provide further evidence that the dopaminergic, nigrostriatal projection has a heterogeneous organization.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗

PubMed1992

Patterns of elevated free calcium and calmodulin activation in living cells.

The temporal and spatial dynamics of intracellular signals and protein effectors are being defined as a result of imaging using fluorescent reagents within living cells. We have described a new class of fluorescent analogues termed optical biosensors, which sense chemical or molecular events through their effects on protein transducers. One example of this new class of indicators is MeroCaM, an environmentally sensitive fluorophore which when it is attached to calmodulin reflects the activation of calmodulin by calcium in vitro. We report here that the rise in free calcium and MeroCaM activation occur in the same period during serum stimulation of quiescent fibroblasts. MeroCaM activation also correlates with the spatial pattern of increased free calcium and the contraction of transverse fibres during wound healing. Finally, migrating fibroblasts in the later stages of wound-healing exhibit an increasing gradient of free calcium and MeroCaM activation from the front to the rear.

3T3 Cells↗

PubMed1983

Bithorax phenocopy and pattern formation. II. A model of prepattern formation.

Phenocopy maps are constructed from the spatial pattern of the phenocopy spots using a distance function defined on the frequencies with which two compartments transform separately and jointly. The temporal changes in distances between different compartments in turn enable us to make inferences concerning the diffusion-like processes involved in prepattern formation of the metathorax. A model is presented which accounts for the data in terms of the propagation of two wavefronts in sequence and in approximately orthogonal directions. Sensitivity to transformation by ether is limited in time to the interval between the passing of the two wavefronts. Changes caused by 13 successive generations of ether treatment can be interpreted in terms of alterations in the timing and rates of wave propagation. A comparison of phenocopy and fate maps suggests that the prepatterning processes affect primarily the blastoderm cytoplasm or surface membrane.

Animals↗

PubMed1983

Propagation through electrically coupled cells. Effects of regional changes in membrane properties.

The normal process of excitation of the heart involves propagation of action potentials through cardiac regions of different anatomy and different intrinsic membrane properties. Although our understanding of these properties is still incomplete, it is well accepted that the parameters measured from a single cell penetration in an electrical syncytium (e.g., action potential duration, rate of rise, and velocity) reflect not only the properties of that cell but also the electrotonic interactions with other cells to which the recorded cell is electrically coupled. We have used simulation techniques to predict the spatial distribution of action potential parameters resulting from discretely localized alterations in the intrinsic membrane properties of some of the cells of an electrical syncytium. We have shown that the resulting spatial distribution is markedly different for alterations in plateau and pacemaker currents vs. rising phase currents, and that other factors, such as the site of stimulation and the underlying spatial pattern of cell-cell coupling resistance, also modify the spatial distribution of action potential properties resulting from a discrete regional change in intrinsic membrane properties.

Action Potentials↗

PubMed1989

Progressively restricted expression of a homeo box gene within the aboral ectoderm of developing sea urchin embryos.

A homeo box-containing gene, Hbox1 is expressed in an unusual and highly conserved spatial pattern in embryos of two different species of sea urchin, Tripneustes gratilla and Strongylocentrotus purpuratus. Hybridization in situ shows that this mRNA accumulates initially throughout the aboral ectoderm; however, between blastula and pluteus stages, the region containing Hbox1 mRNA retracts gradually until only a small area around the vertex is labeled in pluteus larvae. Aboral ectoderm appears cytologically uniform and also accumulates uniform levels of other tissue-specific mRNAs. Therefore, the Hbox1 pattern reveals a previously unsuspected heterogeneity of aboral ectoderm cells and a polarity within this tissue. In S. purpuratus, the Hbox1 gene product probably is not involved in initial specification of cell fate, as this message does not achieve a significant fraction of its peak abundance until almost hatching blastula stage, well after the time aboral ectoderm cells have initiated a tissue-specific program of gene expression. RNA blot and RNase protection analyses revealed low levels of Hbox1 mRNA in all adult tissues examined. However, this message was not detectable in mature eggs, suggesting that the Hbox1 gene does not have a maternal function. In addition to highly conserved spatial and temporal patterns of expression, the homeo box genes of these two urchin species also are conserved highly in sequences outside the homeo domain, despite the divergence of these two species (30-45 my). Two notable features of the protein shared with several vertebrate homeo proteins are a short conserved sequence encoded by an exon upstream of that encoding the homeo domain and a large region of high serine and proline content.

Amino Acid Sequence↗

PubMed1990

Asymmetries in hand movement during block design construction.

Changes in patterns of hand use were examined as a function of task demand characteristics. Using blocks, right- and left-handed male and female subjects were asked to simultaneously construct two replicas of presented patterns, one with each hand. With the presentation of visual-spatial patterns, a shift toward use of the left hand from baseline was observed. This change was least evident among right-handed females. The observed shift in hand use toward the left on a visuo-constructive block design task might suggest differential involvement of the right hemisphere with changes in task demand characteristics.

Adult↗