Spatial Discrimination Research Articles

Generative Dual-Adversarial Network With Spectral Fidelity and Spatial Enhancement for Hyperspectral Pansharpening.

Hyperspectral (HS) pansharpening is of great importance in improving the spatial resolution of HS images for remote sensing tasks. HS image comprises abundant spectral contents, whereas panchromatic (PAN) image provides spatial information. HS pansharpening constitutes the possibility for providing the pansharpened image with both high spatial and spectral resolution. This article develops a specific pansharpening framework based on a generative dual-adversarial network (called PS-GDANet). Specifically, the pansharpening problem is formulated as a dual task that can be solved by a generative adversarial network (GAN) with two discriminators. The spatial discriminator forces the intensity component of the pansharpened image to be as consistent as possible with the PAN image, and the spectral discriminator helps to preserve spectral information of the original HS image. Instead of designing a deep network, PS-GDANet extends GANs to two discriminators and provides a high-resolution pansharpened image in a fraction of iterations. The experimental results demonstrate that PS-GDANet outperforms several widely accepted state-of-the-art pansharpening methods in terms of qualitative and quantitative assessment.

Different reference frames on different axes: Space and language in indigenous Amazonians.

Spatial cognition is central to human behavior, but the way people conceptualize space varies within and across groups for unknown reasons. Here, we found that adults from an indigenous Bolivian group used systematically different spatial reference frames on different axes, according to known differences in their discriminability: In both verbal and nonverbal tests, participants preferred allocentric (i.e., environment-based) space on the left-right axis, where spatial discriminations (like "b" versus "d") are notoriously difficult, but the same participants preferred egocentric (i.e., body-based) space on the front-back axis, where spatial discrimination is relatively easy. The results (i) establish a relationship between spontaneous spatial language and memory across axes within a single culture, (ii) challenge the claim that each language group has a predominant spatial reference frame at a given scale, and (iii) suggest that spatial thinking and language may both be shaped by spatial discrimination abilities, as they vary across cultures and contexts.

Early Drought Stress Warning in Plants: Color Pictures of Photosystem II Photochemistry

Drought, the major limiting factor for plant growth and crop productivity, affecting several physiological and biochemical processes, is expected to increase in duration, intensity, and frequency as a consequence of climate change. Plants have developed several approaches to either avoid or tolerate water deficit. Plants as a response to drought stress (DS), close stomata, reducing carbon dioxide (CO2) entry in the leaf, thus decreasing photosynthesis which results in reduced synthesis of essential organic molecules that sustain the life on earth. The reduced CO2 fixation, decreases electron transport rate (ETR), while the absorbed light energy overdoes what can be used for photochemistry resulting in excess reactive oxygen species (ROS) and oxidative stress. Current imaging techniques allow non-destructive monitoring of changes in the physiological state of plants under DS. Thermographic visualization, near-infrared imaging, and chlorophyll a fluorescence imaging are the most common verified imaging techniques for detecting stress-related changes in the display of light emission from plant leaves. Chlorophyll a fluorescence analysis, by use of the pulse amplitude modulation (PAM) method, can principally calculate the amount of absorbed light energy that is directed for photochemistry in photosystem II (PSII) (ΦPSII), dissipated as heat (ΦNPQ), or dissipated by the non-radiative fluorescence processes (ΦNO). The method of chlorophyll a fluorescence imaging analysis by providing colour pictures of the whole leaf PSII photochemistry, can successfully identify the early drought stress warning signals. Its implementation allowed visualization of the leaf spatial photosynthetic heterogeneity and discrimination between mild drought stress (MiDS), moderate drought stress (MoDS), and severe drought stress (SDS). The fraction of open reaction centers of PSII (qp) is suggested as the most sensitive and suitable indicator of an early drought stress warning and also for selecting drought tolerant cultivars.

Math Instrument Development for Examining the Relationship between Spatial and Mathematical Problem-Solving Skills

Spatial cognition involves the ability to acquire, organize, and use spatial information in the “mind’s eye.” Numerous correlational studies have demonstrated the strong relationship between spatial cognition and skill in problem-solving in mathematics. Educational researchers across the globe aim to improve students’ mathematics problem-solving ability since these skills are often viewed as the gateway to further study in the Science, Technology, Engineering, and Mathematics (STEM) careers of the future. As a result, causal studies showing that spatial cognition interventions can improve mathematics problem-solving skills have begun to appear with increasing frequency. In order to determine if a spatial intervention is effective in improving mathematics problem-solving skills, it is important to identify the type of problem that is likely to respond to improvements in spatial cognition. A large study was conducted in the United States, where a spatial skills intervention was implemented in 7th grade classrooms across the country to determine its impact on mathematics problem-solving skills through four waves of testing. Mathematics instruments for 7th to 9th grades were developed with items compared to the spatial scores of the individual students. In this paper, the instrument development process along with lessons learned are presented. Data are provided showing each item’s correlation with spatial skills test scores, difficulty level, and discrimination index, along with overall instrument reliability. Complete final instruments for each wave of testing are included in an Appendix. General guidelines are also presented discussing the type of math problems likely to be correlated with spatial ability.

Functional dissociation along the rostrocaudal axis of Japanese quail hippocampus.

The mammalian hippocampus (Hp) can be functionally segregated along its septotemporal axis, with involvement of dorsal hippocampus (dHp) in spatial memory and ventral hippocampus (vHp) in stress responses and emotional behaviour. In the present study, we investigate comparable functional segregation in proposed homologues within the avian brain. Using Japanese quail (Coturnix Japonica), we report that bilateral lesions of the rostral hippocampus (rHp) produce robust deficits in a spatial Y-maze discrimination (YMD) test while sparing performance during contextual fear conditioning (CFC), comparable to results from lesions to homologous regions in mammals. In contrast, caudal hippocampus (cHp) lesions failed to produce deficits in either CFC or YMD, suggesting that, unlike mammals, both cHp and rHp of birds can support emotional behavior. These observations demonstrate functional segregation along the rostrocaudal axis of the avian Hp that is comparable in part to distinctions seen along the mammalian hippocampal septotemporal axis.

Late-long-term potentiation magnitude, but not Aβ levels and amyloid pathology, is associated with behavioral performance in a rat knock-in model of Alzheimer disease.

Cleavage of Amyloid precursor protein by β- and γ-secretases lead to Aβ formation. The widely accepted pathogenic model states that these mutations cause AD via an increase in Aβ formation and accumulation of Aβ in Amyloid plaques. APP mutations cause early onset familial forms of Alzheimer's disease (FAD) in humans. We generated App-Swedish (Apps ) knock-in rats, which carry a pathogenic APP mutation in the endogenous rat App gene. This mutation increases β-secretase processing of APP leading to both augmented Aβ production and facilitation of glutamate release in Apps/s rats, via a β-secretase and APP-dependent glutamate release mechanism. Here, we studied 11 to 14-month-old male and female Apps/s rats. To determine whether the Swedish App mutation leads to behavioral deficits, Apps/s knock-in rats were subjected to behavioral analysis using the IntelliCage platform, an automated behavioral testing system. This system allows behavioral assessment in socially housed animals reflecting a more natural, less stress-inducing environment and eliminates experimenter error and bias while increasing precision of measurements. Surprisingly, a spatial discrimination and flexibility task that can reveal deficits in higher order brain function showed that Apps/s females, but not Apps/s male rats, performed significantly worse than same sex controls. Moreover, female control rats performed significantly better than control and Apps/s male rats. The Swedish mutation causes a significant increase in Aβ production in 14-month-old animals of both sexes. Yet, male and female Apps/s rats showed no evidence of AD-related amyloid pathology. Finally, Apps/s rats did not show signs of significant neuroinflammation. Given that the APP Swedish mutation causes alterations in glutamate release, we analyzed Long-term potentiation (LTP), a long-lasting form of synaptic plasticity that is a cellular basis for learning and memory. Strikingly, LTP was significantly increased in Apps/s control females compared to both Apps/s sexes and control males. In conclusion, this study shows that behavioral performances are sex and App-genotype dependent. In addition, they are associated with LTP values and not Aβ or AD-related pathology. These data, and the failures of anti-Aβ therapies in humans, suggest that alternative pathways, such as those leading to LTP dysfunction, should be targeted for disease-modifying AD therapy.

Precise and stable edge orientation signaling by human first-order tactile neurons.

Fast-adapting type 1 (FA-1) and slow-adapting type 1 (SA-1) first-order neurons in the human tactile system have distal axons that branch in the skin and form many transduction sites, yielding receptive fields with many highly sensitive zones or 'subfields.' We previously demonstrated that this arrangement allows FA-1 and SA-1 neurons to signal the geometric features of touched objects, specifically the orientation of raised edges scanned with the fingertips. Here, we show that such signaling operates for fine edge orientation differences (5-20°) and is stable across a broad range of scanning speeds (15-180 mm/s); that is, under conditions relevant for real-world hand use. We found that both FA-1 and SA-1 neurons weakly signal fine edge orientation differences via the intensity of their spiking responses and only when considering a single scanning speed. Both neuron types showed much stronger edge orientation signaling in the sequential structure of the evoked spike trains, and FA-1 neurons performed better than SA-1 neurons. Represented in the spatial domain, the sequential structure was strikingly invariant across scanning speeds, especially those naturally used in tactile spatial discrimination tasks. This speed invariance suggests that neurons' responses are structured via sequential stimulation of their subfields and thus links this capacity to their terminal organization in the skin. Indeed, the spatial precision of elicited action potentials rationally matched spatial acuity of subfield arrangements, which corresponds to a spatial period similar to the dimensions of individual fingertip ridges.

Entorhinal-Hippocampal Circuit Integrity Is Related to Mnemonic Discrimination and Amyloid-β Pathology in Older Adults.

Mnemonic discrimination, a cognitive process that relies on hippocampal pattern separation, is one of the first memory domains to decline in aging and preclinical Alzheimer's disease. We tested whether functional connectivity (FC) within the entorhinal-hippocampal circuit, measured with high-resolution resting state fMRI, is associated with mnemonic discrimination and amyloid-β (Aβ) pathology in a sample of 64 cognitively normal human older adults (mean age, 71.3 ± 6.4 years; 67% female). FC was measured between entorhinal-hippocampal circuit nodes with known anatomical connectivity, as well as within cortical memory networks. Aβ pathology was measured with 18F-florbetapir-PET, and neurodegeneration was assessed with subregional volume from structural MRI. Participants performed both object and spatial versions of a mnemonic discrimination task outside of the scanner and were classified into low-performing and high-performing groups on each task using a median split. Low object mnemonic discrimination performance was specifically associated with increased FC between anterolateral entorhinal cortex (alEC) and dentate gyrus (DG)/CA3, supporting the importance of this connection to object memory. This hyperconnectivity between alEC and DG/CA3 was related to Aβ pathology and decreased entorhinal cortex volume. In contrast, spatial mnemonic discrimination was not associated with altered FC. Aβ was further associated with dysfunction within hippocampal subfields, particularly with decreased FC between CA1 and subiculum as well as reduced volume in these regions. Our findings suggest that Aβ may indirectly lead to memory impairment through entorhinal-hippocampal circuit dysfunction and neurodegeneration and provide a mechanism for increased vulnerability of object mnemonic discrimination.SIGNIFICANCE STATEMENT Mnemonic discrimination is a critical episodic memory process that is performed in the dentate gyrus (DG) and CA3 subfield of the hippocampus, relying on input from entorhinal cortex. Mnemonic discrimination is particularly vulnerable to decline in older adults; however, the mechanisms behind this vulnerability are still unknown. We demonstrate that object mnemonic discrimination impairment is related to hyperconnectivity between the anterolateral entorhinal cortex and DG/CA3. This hyperconnectivity was associated with amyloid-β pathology and neurodegeneration in entorhinal cortex, suggesting aberrantly increased network activity is a pathological process. Our findings provide a mechanistic explanation of the vulnerability of object compared to spatial mnemonic discrimination in older adults and has translational implications for choice of outcome measures in clinical trials for Alzheimer's disease.

A Novel Hybrid Attention-Driven Multistream Hierarchical Graph Embedding Network for Remote Sensing Object Detection

Multiclass geospatial object detection in high-spatial-resolution remote-sensing images (HSRIs) has recently attracted considerable attention in many remote-sensing applications as a fundamental task. However, the complexity and uncertainty of spatial distribution among multiclass geospatial objects are still huge challenges for object detection in HSRIs. Most current remote-sensing object-detection approaches fall back on deep convolutional neural networks (CNNs). Nevertheless, most existing methods only focus on mining visual characteristics and lose sight of spatial or semantic relation discriminations, eventually degrading object-detection performance in HSRIs. To tackle these challenges, we propose a novel hybrid attention-driven multistream hierarchical graph embedding network (HA-MHGEN) to explore complementary spatial and semantic patterns for improving remote-sensing object-detection performance. Specifically, we first constructed hierarchical spatial graphs for multiscale spatial relation representation. Then, semantic graphs were also constructed by integrating them with the word embedding of object category labels on graph nodes. Afterwards, we developed a self-attention-aware multiscale graph convolutional network (GCN) to derive stronger for intra- and interobject hierarchical spatial relations and contextual semantic relations, respectively. These two relation networks were followed by a novel cross-attention-driven spatial- and semantic-feature fusion module that utilizes a multihead attention mechanism to learn associations between diverse spatial and semantic correlations, and guide them to endowing a more powerful discrimination ability. With the collaborative learning of the three relation networks, the proposed HA-MHGEN enables grasping explicit and implicit relations from spatial and semantic patterns, and boosts multiclass object-detection performance in HRSIs. Comprehensive and extensive experimental evaluation results on three benchmarks, namely, DOTA, DIOR, and NWPU VHR-10, demonstrate the effectiveness and superiority of our proposed method compared with that of other advanced remote-sensing object-detection methods.

Gas spreading detection by means of a terahertz leaky-wave antenna

A spectroscopy system for gas detection based on a terahertz (THz) parallel-plate waveguide leaky-wave antenna is presented. Compared to conventional THz spectroscopy systems, we exploit the intrinsic dispersive behavior of a leaky-wave antenna to detect multiple spectral absorption peaks of the considered target. The proposed THz antenna is tested and validated by means of full-wave simulations and experimental measurements on a manufactured prototype. A gas detection experiment considering acetonitrile (i.e., CH3CN) has been carried out to characterize the performance of the spectroscopy system. The directional patterns of the leaky-wave antenna are demonstrated to map the absorption characteristic peaks of the CH3CN, thus enabling an extension of the detection range. Thanks to the intrinsic frequency-scanning behavior of the antenna, each absorption peak can be associated with an angle, enabling, therefore, spatial discrimination to monitor gas spreading.

Comparative study of immunological biomarkers in the carpet shell clams (Ruditapes decussatus) from metal-contaminated sites in the South Lagoon of Tunis (Tunisia)

The South Lagoon of Tunis (Tunisia) is a Mediterranean lagoon adversely affected by industrial contaminants, harbour activity and untreated urban sewage. In this lagoon, the clam Ruditapes decussatus has been widely used as a biomonitor of seawater pollution through measurements of parameters related to oxidative stress and neurotoxicity. However, few studies have considered parameters of the immune system of this species in the South Lagoon of Tunis. Therefore, the aim of the present work was to evaluate several immune-related parameters in the cell-free haemolymph of carpet shell clams sampled during August and February from three polluted sites in the South Lagoon of Tunis (S1, S2 and S3) and one less polluted site as a reference site (RS) in order to identify suitable biomarkers for environmental quality assessments of this ecosystem. Concerning the immune-related parameters, seasonal factors modulated phenoloxidase, lysozyme, protease and esterase activity, with lower values measured for samples collected in August than for samples collected in February. In fact, bactericidal activity against two of the pathogenic bacteria tested and the activity of most immune-related enzymes were reduced in the cell-free haemolymph of clams collected from the most sampling sites in August compared to February one. In addition, values of abiotic parameters (temperature, salinity and pH) and metal (cadmium, copper, iron, lead and zinc) concentrations in the clams’ soft tissues, previously obtained and published by the authors, as well as the values of immune-related parameters were integrated using principal component analyses. Results indicated that the values of all measured immune-related parameters were negatively correlated with the temperature values and the variations most of these parameters highlighted that the chemical industrial area (S3) was the most impacted location within the South Lagoon of Tunis. The present study illustrates that the immune-related parameters measured in carpet shell clam cell-free haemolymph represent suitable biomarkers for environmental quality assessments because they provide effective seasonal and spatial discrimination.

Impacts of neonatal methylmercury on behavioral flexibility and learning in spatial discrimination reversal and visual signal detection tasks

Early postnatal development in rodents is sensitive to neurotoxic effects of the environmental contaminant, methylmercury. While juvenile and adolescent exposure also produce long-term impairments in behavior, the outcome of neonatal exposure is less understood. Neural development during the neonatal period in rodents is akin to that seen in humans during the third trimester of pregnancy but methylmercury exposure occurring during the neonatal period has not been modeled, partly because breast milk is a poor source of bioavailable methylmercury. To examine this developmental period, male Long-Evans rats were exposed to 0, 80, or 350 µg/kg/day methylmercuric chloride from postnatal days 1–10, the rodent neonatal period. As adults, behavioral flexibility, attention, memory, and expression of the dopamine transporter in these rats was assessed. Rats exhibited changes in behavioral flexibility assessed in a spatial discrimination reversal procedure. Those rats exposed to the highest dose of methylmercury displayed subtly altered patterns of perseveration compared to control animals. During acquisition of the attention/memory procedure, rats exposed to this dose also had slower acquisition, and achieved lower overall accuracy during training, compared to controls despite neither attention nor memory being affected once the task was acquired. Finally, dopamine transporter expression in the striatum, prefrontal cortex, and hippocampus was unchanged in these adult rats. The results of this study replicate the trend of findings seen with exposure during gestation or during adolescence.

Anterior thalamic nuclei: A critical substrate for non-spatial paired-associate memory in rats.

Injury or dysfunction in the anterior thalamic nuclei (ATN) may be the key contributory factor in many instances of diencephalic amnesia. Experimental ATN lesions impair spatial memory and temporal discriminations, but there is only limited support for a more general role in non-spatial memory. To extend evidence on the effects of ATN lesions, we examined the acquisition of biconditional associations between odour and object pairings presented in a runway, either with or without a temporal gap between these items. Intact adult male rats acquired both the no-trace and 10-s trace versions of this non-spatial task. Intact rats trained in the trace version showed elevated Zif268 activation in the dorsal CA1 of the hippocampus, suggesting that the temporal component recruited additional neural processing. ATN lesions completely blocked acquisition on both versions of this association-memory task. This deficit was not due to poor inhibition to non-rewarded cues or impaired sensory processing, because rats with ATN lesions were unimpaired in the acquisition of simple odour discriminations and simple object discriminations using similar task demands in the same apparatus. This evidence challenges the view that impairments in arbitrary paired-associate learning after ATN lesions require the use of multimodal spatial stimuli. It suggests that diencephalic amnesia associated with the ATN stems from degraded attention to stimulus-stimulus associations and their representation across a distributed memory system.

Urban Piss-Ups. The collective filmmaking of parodic urban fables to study and contest gender spatial discriminations

For Haraway (2016), ‘speculative fabulations’ are an interweaving of facts and fiction that allows imagining alternative futures. In this paper, I recount the experience of collectively writing three speculative fabulations about urban gender discrimination. ‘Urban fables’ refer to the centrality of space in the narration. Together with the participants, 11 white cisgender women, we turned each urban fable into a collective amatorial short film with a fabulist political moral. Firstly, I reflect on the collective process that led to the creation of the three short films; secondly, on the analytical and interpretative qualities of fiction to imagine new spatial realities; and thirdly, on the use of parody as a critical tool to study and represent urban discrimination. Through the short film Urban Piss-Ups, I propose a counter-hegemonic, nonviolent research experience grounded in the collective and playful endeavour of geographical filmmaking and parodic practice. I conclude by discussing how the joint qualities of collective filmmaking, fiction, and parody engender a powerful tool to study spatial discriminations and to enrich research results by helping the dissemination of its content beyond the academy.

Age-related loss of recognition memory and its correlation with hippocampal and perirhinal cortex changes in female Sprague Dawley rats

Ageing is associated with impaired performance in recognition memory, a process that consists of the discrimination of familiar and novel stimuli. Previous studies have shown the impact of ageing on object recognition memories. However, the early stages of memory impairment remain unknown. To fill this gap, we aimed at evaluating the ability of young (Y), middle-aged (MA), and senile (S) female Sprague-Dawley rats to retain 24 h long-term recognition memory. The MA cohort was included to characterise early memory deficits under two behavioural paradigms based on spontaneous location recognition (SLR) and spontaneous object recognition (SOR) tasks. In the SLR task, there was a markedly diminished novel discrimination capacity in the MA and S rats compared with the Y ones. In the SOR task, S rats evidenced a deterioration in novelty discrimination, while MA rats partially preserved the capacity to distinguish the new stimulus as compared with Y rats. Regarding early changes from MA to S rats, immunohistochemistry showed a marked decrease in the number and diameter of adult-born immature neurons in the Dentate Gyrus (DG) with a positive correlation with behavioural performance in the SLR task. Furthermore, we found a slight reduction in CA3 mature neurons and a decrease in the number of total microglia in the perirhinal cortex (Prh) in MA and S rats as compared with Y rats. As regards changes that were only observed in S rats, we found an increase in the number of total and reactive microglia in CA3 and a reduction in the number of total microglia in the DG. We conclude that spatial discrimination capacity could be affected earlier than feature discrimination capacity. We suggest that early depletion of neurogenesis in MA rats is involved in object location recognition deficits, whereas the disruption of microglial homeostasis in the Prh could be associated with object feature discrimination capacity.

Dimensionless Characterization to Estimate Horizontal Groundwater Velocity from Temperature–Depth Profiles in Aquifers

The outcome of a dimensionless characterization study in a two-dimensional porous media domain in which groundwater flows at a constant horizontal velocity is presented in this report. Using spatial discrimination, the dimensionless groups that govern the solution patterns are determined from dimensionless governing equations. As a boundary condition on the surface, the case of constant temperature is studied. From the mathematical deduction of the groups, a characteristic horizontal length emerges. This length determines the region in which temperature–depth profiles are affected by flow. Existing analytical solutions have been shown to be invalid due to the severe assumption that the horizontal thermal gradient has a constant value. Therefore, universal solutions based on pi theorem have been obtained for the characteristic horizontal length, temperature field, temperature–depth profiles and horizontal temperature profiles. Dependencies between dimensionless groups have been depicted by universal curves, abacuses and surfaces. These graphical solutions are used in an easy way to estimate groundwater velocity from experimental temperature measurements in the form of an inverse problem. In addition, an easy and fast protocol for estimating fluid flow velocity and groundwater inlet temperature from temperature profile measurements is proposed. This protocol is applied in a scenario of groundwater discharge from a quaternary aquifer to a salty lagoon located in the southeast of Spain.

Employing spatial and amplitude discriminators to partition and analyze LPBF surface features

The surface characteristics of Laser powder bed fusion (LPBF) components are an increasingly important aspect in assessing their performance as well as qualifying them to established standards. Typical LPBF surface features include layer-by-layer staircase edges, laser tracks, various degrees of balling, unfused/partially melted powder, spatter particles, and solidification chevrons. They present differently depending on being located on the component's top, side, up or down skins. Their spatial and amplitude features can also vary widely in magnitude depending on the alloy and process parameters involved. Although a significant body of work exists on characterizing LPBF surfaces, there is still little understanding of the cause-effect relationships they have with LPBF process parameters. Hence, there is limited capacity to tailor/optimize surface characteristics for specific standards/applications, such as fatigue performance, wear resistance, implant-bone biointegration, heat exchanger optimization, etc. Before the causal relationships can be explored, one must understand which LPBF characteristic feature or features are controlling a particular LPBF surface roughness. This work describes a new approach to the multiscale characterization and analysis of surfaces specific to LPBF. The method applies spatial and amplitude discriminators to partition LPBF features into separate topographies, enabling an assessment of their individual contribution to surface roughness. It involved systematically varying the cut-off wavelength over the entire spatial range of the surface and detecting discrete transitions in surface field parameters that identified a change in the dominant surface feature. The cut-off wavelengths where these transitions occurred were then used to partition the surface into separate topographies containing particular surface features. This enabled an independent assessment of their individual contribution to overall roughness. The method was demonstrated on LPBF top surfaces using five process parameter sets spanning from low to high energy density. It was successful in determining the segmentation cut-off wavelengths of each set, enabling an assessment of their individual contribution to overall surface roughness. The results indicate that this method has the potential to enable exploration of the causal relationships between process parameters and specific surface features as well as provide a basis for tailoring LPBF surfaces.

Suprathreshold perceptual decisions constrain models of confidence.

Perceptual confidence is an important internal signal about the certainty of our decisions and there is a substantial debate on how it is computed. We highlight three confidence metric types from the literature: observers either use 1) the full probability distribution to compute probability correct (Probability metrics), 2) point estimates from the perceptual decision process to estimate uncertainty (Evidence-Strength metrics), or 3) heuristic confidence from stimulus-based cues to uncertainty (Heuristic metrics). These metrics are rarely tested against one another, so we examined models of all three types on a suprathreshold spatial discrimination task. Observers were shown a cloud of dots sampled from a dot generating distribution and judged if the mean of the distribution was left or right of centre. In addition to varying the horizontal position of the mean, there were two sensory uncertainty manipulations: the number of dots sampled and the spread of the generating distribution. After every two perceptual decisions, observers made a confidence forced-choice judgement whether they were more confident in the first or second decision. Model results showed that the majority of observers were best-fit by either: 1) the Heuristic model, which used dot cloud position, spread, and number of dots as cues; or 2) an Evidence-Strength model, which computed the distance between the sensory measurement and discrimination criterion, scaled according to sensory uncertainty. An accidental repetition of some sessions also allowed for the measurement of confidence agreement for identical pairs of stimuli. This N-pass analysis revealed that human observers were more consistent than their best-fitting model would predict, indicating there are still aspects of confidence that are not captured by our modelling. As such, we propose confidence agreement as a useful technique for computational studies of confidence. Taken together, these findings highlight the idiosyncratic nature of confidence computations for complex decision contexts and the need to consider different potential metrics and transformations in the confidence computation.

Sphingolipids and DHA Improve Cognitive Deficits in Aged Beagle Dogs

Canine cognitive dysfunction syndrome (CDS) is a disorder found in senior dogs that is typically defined by the development of specific behavioral signs which are attributed to pathological brain aging and no other medical causes. One way of objectively characterizing CDS is with the use of validated neuropsychological test batteries in aged Beagle dogs, which are a natural model of this condition. This study used a series of neuropsychological tests to evaluate the effectiveness of supplementation with a novel lipid extract containing porcine brain-derived sphingolipids (Biosfeen®) and docosahexaenoic acid (DHA) for attenuating cognitive deficits in aged Beagles. Two groups (n = 12), balanced for baseline cognitive test performance, received a daily oral dose of either test supplement, or placebo over a 6-month treatment phase. Cognitive function was evaluated using the following tasks: delayed non-matching to position (DNMP), selective attention, discrimination learning retention, discrimination reversal learning, and spatial discrimination acquisition and reversal learning. The effect of the supplement on brain metabolism using magnetic resonance spectroscopy (MRS) was also examined. A significant decline (p = 0.02) in DNMP performance was seen in placebo-treated dogs, but not in dogs receiving the supplement, suggesting attenuation of working memory performance decline. Compared to placebo, the supplemented group also demonstrated significantly improved (p = 0.01) performance on the most difficult pattern of the spatial discrimination task and on reversal learning of the same pattern (p = 0.01), potentially reflecting improved spatial recognition and executive function, respectively. MRS revealed a significant increase (p = 0.048) in frontal lobe glutamate and glutamine in the treatment group compared to placebo, indicating a physiological change which may be attributed to the supplement. Decreased levels of glutamate and glutamine have been correlated with cognitive decline, suggesting the observed increase in these metabolites might be linked to the positive cognitive effects found in the present study. Results of this study suggest the novel lipid extract may be beneficial for counteracting age-dependent deficits in Beagle dogs and supports further investigation into its use for treatment of CDS. Additionally, due to parallels between canine and human aging, these results might also have applicability for the use of the supplement in human cognitive health.

Discrimination of soil magnetism enhanced by land use and its implications for inferring alterations in sediment sources and soil erosion in a homogeneous watershed: An example from the Guizhou Plateau, SW China

This paper demonstrates that land use could enhance spatial discrimination of soil magnetism in a homogeneous watershed, and such differences help infer alterations in sediment sources and erosion. One sediment core was sampled from a reservoir built in 1958 and fifteen soil profiles from its catchment on the southern Guizhou Plateau, SW China. The whole watershed was covered by yellow earth developed on limestone. Magnetic measurements and granulometric analysis were performed on the soils and sediments while TOC and TN analysis on two soil profiles and 137Cs analysis on the sediment core. Information of seven years' land-use was derived from remote sensing images. The farmland and grassland soils had different magnetic characteristics while the downwards distributions of TOC and C/N were similar in the two profiles. The grassland soils had higher HIRM, lower χfd% and IRM300mT/SIRM. The higher χfd% and IRM300mT/SIRM of the farmland soils suggested stronger pedogenesis under cultivation. The average HIRM, χfd% and IRM300mT/SIRM were 38 and 334 10-6 A m2 kg−1, 5.7 and 3.6%, and 0.91 and 0.66 for the farmland and grassland soils. The farmland soils were finer probably due to tillage. The reservoir has been closely surrounded mainly by the grassland whereas the farmland, embedded with patches of the grassland, has occurred in the terrains relatively distant from the reservoir. The sediments of 1958–1985 had lower HIRM (156 10-6 A m2 kg−1) and higher IRM300mT/SIRM (0.79), indicating greater contributions of the remote farmland soils mixed with grassland soils and stronger erosion. HIRM increased (229 10-6 A m2 kg−1) and IRM300mT/SIRM decreased (0.67) in the sediments of 1985–2019, implying decreased distant-soil contributions and relatively increased input of the grassland soil closely around the reservoir. Erosion thus weakened, as proven by the finer sediments. The declining erosion was mainly due to farmland shrinkage and grassland expansion.