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PubMed1997

Spatial analysis of the distribution of LaCrosse encephalitis in Illinois, using a geographic information system and local and global spatial statistics.

The spatial and temporal distribution of LaCrosse encephalitis cases in Illinois was analyzed using a geographic information system (GIS) and spatial statistics. Case data were obtained from the Illinois Department of Public Health and mapped on the county, town, and address level. Human cases were concentrated in and around the city of Peoria in central Illinois. Local spatial statistics were used to identify hot spots where cases appear to be concentrated in the Peoria region. Several small towns surrounding the city of Peoria appeared as foci where cases were most common. Second-order spatial analysis of the case distribution was conducted on the address level. Cases were clustered within a range of 3.0 km in the city of Peoria. Since most cases appear to be associated with residential (peridomestic) exposure, and since several cases have been reported from neighboring addresses, transmission may be concentrated around specific sites (hardwood ravines, tire piles). The GIS and spatial analysis may be useful in identifying and targeting for intervention potential sites of enzootic transmission.

Adolescent↗

PubMed1994

The avian hippocampus and short-term memory for spatial and non-spatial information.

Three experiments investigated the role of the pigeon hippocampal formation (the hippocampus and area-parahippocampalis) in short-term memory for non-spatial and spatial information. The acquisition of delayed matching-to-sample and the short-term retention of non-spatial visual information, using a small set of sample stimuli, were unaffected by aspiration lesions of the hippocampus or the neostriatum (Experiment 1). Similarly, acquisition and short-term retention of non-spatial information using a successive, trial-unique, delayed non-matching-to-sample procedure were unaffected by hippocampal damage; the same birds had, however, displayed a profound autoshaping impairment (Experiment 2). Acquisition of a spatial delayed matching-to-sample task was unimpaired by hippocampal damage. However, lesioned animals were impaired following the introduction of retention intervals on this procedure (Experiment 3). The correspondence between the behavioural effects of hippocampal lesions in birds and mammals on short-term memory is discussed, and the implications of these results for avian hippocampal function are considered.

Animals↗

PubMed1989

Hippocampal granule cells are necessary for normal spatial learning but not for spatially-selective pyramidal cell discharge.

The effects of massive destruction of granule cells of the fascia dentata on the spatial and temporal firing characteristics of pyramidal cells in the CA1 and CA3 subfields of the hippocampus were examined in freely moving rats. Microinjections of the neurotoxin colchicine were made at a number of levels along the septo-temporal axis of the dentate gyri of both hemispheres, resulting in destruction of over 75% of the granule cells. By contrast there was relatively little damage to the pyramidal cell fields. As assessed by three different behavioral tests, the colchicine treatment resulted in severe spatial learning deficits. Single units were recorded from the CA1 and CA3 subfields using the stereotrode recording method while the animals performed a forced choice behavioral task on the radial 8-arm maze. Considering the extent of damage to the dentate gyrus, which has hitherto been considered to be the main source of afferent information to the CA fields, there was remarkably little effect on the spatial selectivity of "place cell" discharge on the maze, as compared to recordings from control animals. There was, however, a change in the temporal firing characteristics of these cells, which was manifested primarily as an increase in the likelihood of burst discharge. The main conclusion derived from these findings is that most of the spatial information exhibited by hippocampal pyramidal cells is likely to be transmitted from the cortex by routes other than the traditional "trisynaptic circuit". These routes may include the direct projections from entorhinal layers II and III to CA3 and CA1, respectively.

Animals↗

PubMed2026

Integrated single-cell and spatial transcriptomic analyses reveal malignant epithelial glycolytic heterogeneity and spatial niche remodeling during colorectal cancer progression.

Colorectal cancer (CRC) progression is shaped by metabolic reprogramming and complex interactions within the tumor microenvironment. However, the cellular heterogeneity, spatial organization, and clinical relevance of glycolytic activity in CRC remain incompletely understood. In this study, we integrated single-cell RNA sequencing, bulk transcriptomics, and spatial transcriptomics data to systematically characterize glycolytic heterogeneity in CRC. Glycolytic activity was quantified using five independent scoring methods, consistently showing that epithelial cells exhibited the highest glycolytic activity across the two single-cell cohorts. Stratification of CopyKAT-verified aneuploid malignant epithelial cells into high-glycolysis (HG) and low-glycolysis (LG) subgroups by glycolysis scores revealed that HG cells exhibited higher stemness scores and chromosomal copy number variations. Cell-cell communication analysis revealed that, compared with LG cells, HG cells exhibited increased interaction frequency and strength with immune and stromal populations, indicating enhanced malignant epithelial-microenvironment crosstalk. Spatial transcriptomics analyses further revealed that glycolytic activity varied across normal colorectal tissue, primary CRC, and colorectal liver metastases, accompanied by progressive remodeling of epithelial-associated spatial niches and MIF-mediated intercellular communication. Bulk transcriptomic analysis identified a glycolysis-related prognostic signature with robust predictive performance, which served as an independent prognostic factor for overall survival in CRC cohorts. Collectively, these findings indicate that glycolytic heterogeneity is a key feature of CRC malignant epithelial cells and is closely associated with tumor progression, microenvironmental remodeling, and clinical outcomes.

Humans↗

PubMed2004

Comparison of the effects of entorhinal and retrosplenial cortical lesions on habituation, reaction to spatial and non-spatial changes during object exploration in the rat.

This study was aimed at comparing the effects of damage to the entorhinal cortex and retrosplenial cortex on exploration and reaction-to-change in rats. Following habituation to a configuration of objects, a familiar object was displaced therefore producing a spatial change. A non-spatial change was made by substituting a familiar object by a novel object. Both entorhinal cortex lesions and retrosplenial cortex lesions elicited a deficit in the rat's reaction to a spatial change. In addition, rats with entorhinal lesions showed hypoactive object exploration and exhibited a mild deficit in reaction to a non-spatial change. This may reflect the importance of temporal cortical input in object recognition. Overall, these results suggest that the entorhinal cortex and the retrosplenial cortex contribute to the processing of the geometric properties of the environment and have thus close functional links.

Animals↗

PubMed2026

Full-length single-cell spatial transcriptomics reveals spatial and cell-type-specific transcript isoforms in the primate brain.

The primate brain exhibits complex RNA alternative splicing heterogeneity crucial for functional complexity, yet systematic spatial isoform characterization has been lacking. We developed Fullscope-seq, a full-length single-molecule large field-of-view spatial transcriptomics sequencing method at single-cell resolution, based on programmed concatenation cDNA for multiple long-read sequencing platforms. Applying Fullscope-seq to the macaque brain, we uncovered thousands of genes exhibiting differential transcript usage (DTU) across cortical layers, cell types and brain regions. Fullscope-seq resolved hundreds of major isoform switches across distinct brain regions and identified DTUs between superficial and deep cortical layers. Cortical layer-specific DTUs showed cell-composition dependence, whereas regional DTUs were regulated according to both cellular composition and spatial contexts. These isoform variations showed substantial enrichment for neuropsychiatric disorder-associated genes and were conserved across platforms and species. Our study establishes a scalable framework for spatial isoform analysis and provides a resource for understanding transcriptomic diversity in complex tissues.

Animals↗

PubMed1995

The effects of AMPA-induced lesions of the medial septum and vertical limb nucleus of the diagonal band of Broca on spatial delayed non-matching to sample and spatial learning in the water maze.

These experiments investigated in the rat the impact on spatial delayed non-matching to sample and on acquisition of the Morris water maze of (i) AMPA-induced lesions of the medial septal nucleus, which produced a marked reduction of hippocampal choline acetyltransferase activity and acetylcholine levels (measured using in vivo dialysis) together with lesser reductions in cholinergic markers in the cingulate cortex and (ii) similar AMPA-induced lesions of the vertical limb nucleus of the diagonal band of Broca (vDB), which produced more marked reductions in cholinergic markers in the cingulate cortex than in the hippocampus. Medial septal lesions produced a delay-dependent deficit in spatial working memory, while lesions of the vDB resulted in a delay-independent performance deficit. In addition, rats with vDB lesions adopted biased response strategies during the imposition of long delays. Neither lesion significantly affected the acquisition of a spatial reference memory task, the Morris water maze. The results are discussed in terms of cholinergic- and GABAergic-dependent functions of the hippocampal formation and cingulate cortex in spatial short-term and reference memory.

Acetylcholine↗

PubMed2004

The role of high spatial frequencies in hemispheric processing of categorical and coordinate spatial relations.

Right-handed participants performed categorical and coordinate spatial relation tasks on stimuli presented either to the left visual field-right hemisphere (LVF-RH) or to the right visual field-left hemisphere (RVF-LH). The stimuli were either unfiltered or low-pass filtered (i.e., devoid of high spatial frequency content). Consistent with previous studies, the unfiltered condition produced a significant RVF-LH advantage for the categorical task and an LVF-RH advantage for the coordinate task. Low-pass filtering eliminated this Task x Visual Field interaction; thus, the RVF-LH advantage disappeared for the categorical task. The present results suggest that processing of high spatial frequency contributes to the left hemispheric advantage for categorical spatial processing.

Adult↗

PubMed2003

A within-subjects, within-task demonstration of intact spatial reference memory and impaired spatial working memory in glutamate receptor-A-deficient mice.

Gene-targeted mice lacking the AMPA receptor subunit glutamate receptor-A (GluRA) (GluR1) and wild-type controls were compared on a radial-maze task in which the same three of six arms were always baited, but in which the rewards of milk were not replaced within a trial. This procedure allowed not only a within-subjects but also a within-trials assessment of both spatial working memory (WM) and reference memory (RM) in GluRA-/- mice, using identical spatial cues. In experiment 1, the GluRA-/- mice made more WM and RM errors during task acquisition. However, separate groups of GluRA-/- and wild-type mice (experiment 2) acquired a purely RM version of the task at a similar rate, using a paradigm with which it was not possible to make WM errors (doors prevented mice from re-entering an arm that they had already visited on that trial). In contrast, mice with hippocampal lesions were dramatically impaired. These results are consistent with the possibility that the WM impairment in the GluRA-/- mice during experiment 1 produced interference that disrupted RM acquisition. A WM component was therefore introduced after RM acquisition in experiment 2 (i.e., the mice were no longer prevented from re-entering a previously visited arm). The GluRA-/- mice now made considerably more WM errors than did wild-type mice, but simultaneously, RM was only mildly and transiently impaired. These experiments provide additional evidence of a selective spatial WM deficit coexisting with intact spatial RM acquisition in GluRA-/- mice, suggesting that different neuronal mechanisms within the hippocampus may support these different kinds of information processing.

Animals↗

PubMed1998

Effects of unilateral spatial neglect on spatial agraphia of kana and kanji letters.

Left unilateral spatial neglect (USN) and spatial agraphia are both caused by right hemisphere damage. However, effects of USN on spatial agraphia have not been fully investigated. This study examined performances of patients with or without neglect and normals on single letter writing, using Japanese unique writing systems, kana (phonogram) and kanji (ideogram). Our patients exhibited agraphia of kanji, but not of kana. However, accuracy of writing was not associated to neglect severity, and errors for writing to dictation occurred either on the left or right side of kanji. Right frontal damage seemed to be related to the genesis of duplication or omission errors of repeated elements. Effect of USN was limited to spatial arrangement of letters and copying performance.

Aged↗

PubMed2005

Spatial and non-spatial auditory processing in the lateral intraparietal area.

We tested the responses of neurons in the lateral parietal area (area LIP) for their sensitivity to the spatial and non-spatial attributes of an auditory stimulus. We found that the firing rates of LIP neurons were modulated by both of these attributes. These data indicate that, while area LIP is involved in spatial processing, non-spatial processing is not restricted to independent channels.

Acoustic Stimulation↗

PubMed2003

Forward masking of faces by spatially quantized random and structured masks: on the roles of wholistic configuration, local features, and spatial-frequency spectra in perceptual identification.

The forward masking of faces by spatially quantized masking images was studied. Masks were used in order to exert different types of degrading effects on the early representations in facial information processing. Three types of source images for masks were used: Same-face images (with regard to targets), different-face images, and random Gaussian noise that was spectrally similar to facial images. They were all spatially quantized over the same range of quantization values. Same-face masks had virtually no masking effect at any of the quantization values. Different-face masks had strong masking effects only with fine-scale quantization, but led to the same efficiency of recognition as in the same-face mask condition with the coarsest quantization. Moreover, compared with the noise-mask condition, coarsely quantized different-face masks led to a relatively facilitated level of recognition efficiency. The masking effect of the noise mask did not vary significantly with the coarseness of quantization. The results supported neither a local feature processing account, nor a generalized spatial-frequency processing account, but were consistent with the microgenetic configuration-processing theory of face recognition. Also, the suitability of a spatial quantization technique for image configuration processing research has been demonstrated.

Adult↗

PubMed2006

Spatial heterogeneity in parasite infections at different spatial scales in an intertidal bivalve.

Spatial heterogeneities in the abundance of free-living organisms as well as in infection levels of their parasites are a common phenomenon, but knowledge on parasitism in invertebrate intermediate hosts in this respect is scarce. We investigated the spatial pattern of four dominant trematode species which utilize a common intertidal bivalve, the cockle Cerastoderma edule, as second intermediate host in their life cycles. Sampling of cockles from the same cohort at 15 sites in the northern Wadden Sea (North Sea) over a distance of 50 km revealed a conspicuous spatial heterogeneity in infection levels in all four species over the total sample as well as among and within sampling sites. Whereas multiple regression analyses indicated the density of first intermediate upstream hosts to be the strongest determinant of infection levels in cockles, the situation within sites was more complex with no single strong predictor variable. However, host size was positively and host density negatively correlated with infection levels and there was an indication of differential susceptibility of cockle hosts. Small-scale differences in physical properties of the habitat in the form of residual water at low tide resulted in increased infection levels of cockles which we experimentally transferred into pools. A complex interplay of these factors may be responsible for within-site heterogeneities. At larger spatial scales, these factors may be overridden by the strong effect of upstream hosts. In contrast to first intermediate trematode hosts, there was no indication for inter-specific interactions. In other terms, the recruitment of trematodes in second intermediate hosts seems to be largely controlled by pre-settlement processes both among and within host populations.

Animals↗

PubMed2006

Mapping the spatial variability of plant diversity in a tropical forest: comparison of spatial interpolation methods.

Knowledge of the spatial distribution of plant species is essential to conservation and forest managers in order to identify high priority areas such as vulnerable species and habitats, and designate areas for reserves, refuges and other protected areas. A reliable map of the diversity of plant species over the landscape is an invaluable tool for such purposes. In this study, the number of species, the exponent Shannon and the reciprocal Simpson indices, calculated from 141 quadrat sites sampled in a tropical forest were used to compare the performance of several spatial interpolation techniques used to prepare a map of plant diversity, starting from sample (point) data over the landscape. Means of mapped classes, inverse distance functions, kriging and co-kriging, both, applied over the entire studied landscape and also applied within vegetation classes, were the procedures compared. Significant differences in plant diversity indices between classes demonstrated the usefulness of boundaries between vegetation types, mapped through satellite image classification, in stratifying the variability of plant diversity over the landscape. These mapped classes, improved the accuracy of the interpolation methods when they were used as prior information for stratification of the area. Spatial interpolation by co-kriging performed among the poorest interpolators due to the poor correlation between the plant diversity variables and vegetation indices computed by remote sensing and used as covariables. This indicated that the latter are not suitable covariates of plant diversity indices. Finally, a within-class kriging interpolator yielded the most accurate estimates of plant diversity values. This interpolator not only provided the most accurate estimates by accounting for the indices' intra-class variability, but also provided additional useful interpretations of the structure of spatial variability of diversity values through the interpretation of their semi-variograms. This additional role was found very useful in aiding decisions in conservation planning.

Models, Theoretical↗

PubMed1987

Modulation of visual event-related potentials by spatial and non-spatial visual selective attention.

Event-related potentials (ERPs) were recorded in two experiments involving selective visual processing. In Experiment 1, subjects attended to light flashes emanating from one visual field, in order to detect occasional slightly deviant "targets", while ignoring equiprobable stimuli from the opposite field. ERPs elicited by stimuli in an attended field were characterised by larger posteriorly distributed P120 and N170 components, and a larger anteriorly distributed N145 component. In addition, these ERPs were, in comparison to those elicited by unattended stimuli, more negative-going in the latency region of approx. 200-400 msec. This late effect had a marked fronto-central distribution. In Experiment 2 subjects attended to either horizontal or vertical bars, displayed equiprobably in the same spatial location. No enhancement of early components was observed as a function of attention but, as in Experiment 1, a late, sustained, fronto-centrally distributed negative shift was observed in ERPs elicited by "attended" compared to "unattended" stimuli. It was concluded that the enhancement of P120 (P1) observed in Experiment 1 reflects the engagement of attentional mechanisms specific to the selection of stimuli on the basis of spatial cues. The later sustained negative shift seen in both experiments was considered to reflect a feature of within-channel processing common to both spatial and non-spatial selective tasks.

Adult↗

PubMed1991

A model for perceived spatial frequency and spatial frequency discrimination.

The responses of labelled spatial frequency channels are combined to generate an index of perceived spatial frequency. Spatial frequency discrimination thresholds are shown to be inversely related to the slope of the function of the index vs spatial frequency, when it is plotted on log-log co-ordinates.

Discrimination, Psychological↗

PubMed1992

The coding of spatial position by the human visual system: effects of spatial scale and contrast.

In this study we investigate the nature of the computations that underlie the encoding of spatial position by the human visual system. Specifically, we explore the relationship between alignment accuracy and spatial scale on the one hand, and between alignment accuracy and contrast on the other. We do this for stimuli where local luminance, local contrast, and orientation cues do not underlie performance. The results suggest that spatial localisation is independent of spatial scale and weakly dependent on contrast. We present subsequent models based on the properties of some classes of visual cortical neurones, namely multiplicative noise and contrast energy detection of complex cells, which describe the form of these relationships.

Contrast Sensitivity↗

PubMed1993

Is the increased spatial uncertainty in the normal periphery due to spatial undersampling or uncalibrated disarray?

There are two possible causes for the elevated positional uncertainty of the peripheral field; undersampling by post receptoral arrays or uncalibrated disarray within post receptoral arrays. In order to assess the relative influences of these two factors to peripheral spatial uncertainty, we apply an approach which has enjoyed much success in the field of colour vision to examine the trade-off between position and contrast errors for spatial vision. We show that, if our positional uncertainty in the periphery is due to spatial undersampling, a correlated contrast inaccuracy should be present. We find no evidence for this expected linkage in the peripheral field at any spatial scale. We conclude that uncalibrated neural disarray rather than undersampling is the cause of peripheral positional uncertainty.

Awareness↗