Blue Squares Research Articles

Determination, expression and characterization of an UDP-N-acetylglucosamine:α-1,3-D-mannoside β-1,2-N-acetylglucosaminyltransferase I (GnT-I) from the Pacific oyster, Crassostrea gigas

Molluscs are intermediate hosts for several parasites. The recognition processes, required to evade the host’s immune response, depend on carbohydrates. Therefore, the investigation of mollusc glycosylation capacities is of high relevance to understand the interaction of parasites with their host. UDP-N-acetylglucosamine:α-1,3-D-mannoside β-1,2-N-acetylglucosaminyltransferase I (GnT-I) is the key enzyme for the biosynthesis of hybrid and complex type N-glycans catalysing the transfer of N-acetylglucosamine from UDP-N-acetylglucosamine to the α-1,3 Man antenna of Man5GlcNAc2. Thereby, the enzyme produces a suitable substrate for further enzymes, such as α-mannosidase II, GlcNAc-transferase II, galactosyltransferases or fucosyltransferases. The sequence of GnT- I from the Pacific oyster, Crassostrea gigas, was obtained by homology search using the corresponding human enzyme as the template. The obtained gene codes for a 445 amino acids long type II transmembrane glycoprotein and shared typical structural elements with enzymes from other species. The enzyme was expressed in insect cells and purified by immunoprecipitation using protein A/G-plus agarose beads linked to monoclonal His-tag antibodies. GnT-I activity was determined towards the substrates Man5-PA, MM-PA and GnM-PA. The enzyme displayed highest activity at pH 7.0 and 30 °C, using Man5-PA as the substrate. Divalent cations were indispensable for the enzyme, with highest activity at 40 mM Mn2+, while the addition of EDTA or Cu2+ abolished the activity completely. The activity was also reduced by the addition of UDP, UTP or galactose. In this study we present the identification, expression and biochemical characterization of the first molluscan UDP-N-acetylglucosamine:α-1,3-D-mannoside β-1,2-N-acetylglucosaminyltransferase I, GnT-I, from the Pacific oyster Crassostrea gigas.Graphical abstractIllustration of GnT-I activity. (a) Transfer of GlcNAc to Man5-PA, creating Man5GlcNAc3-PA. (b) Transfer of GlcNAc to MM-PA, creating MGn-PA. (c) Transfer of GlcNAc to GnM-PA, creating GnGn-PA. Blue squares represent N-acetylglucosamine, green cycles depict mannose. Graphic illustration of N-glycans were created using bioRENDER.

Operando Neutron Imaging of Water Distribution inside Running Anion-Exchange Membrane Fuel Cell

IntroductionAnion-exchange membrane fuel cell (AEMFC) has a potential use of non-precious metal catalysts under an alkaline environment. Furthermore, anion-exchange membranes (AEMs) are expected to be used for water electrolysis. However, the performance of AEMFC is still lower than that of proton-exchange membrane fuel cell (PEMFC). During the power generation, the PEMFC only produces H2O at the cathode, whereas the AEMFC consumes H2O at the cathode and produces twice as much as H2O at the anode. The main factors for the increase in polarization of AEMFC are limitation of H2 diffusion due to liquid water flooding at the anode and lack of H2O as a reactant at the cathode. Therefore, elucidating the water distribution in the AEMFC is essentially important. In this study, we imaged liquid water in an AEMFC during power generation. The data were compared with those of a PEMFC.ExperimentalThe water distribution in the AEMFC was imaged by neutron beams in the directions, perpendicular and parallel to the membrane-electrode assembly (MEA) surface during power generation. Imaging was conducted at the beamline BL-22 of the MLF, J-PARC(2). The cell size was 100×70 mm2, and the active area was 20×20 mm2. Single serpentine flow channels were used for the gas flow channels. The depth and the width of the gas flow channels were both 1 mm. The end plates were made of aluminum to avoid neutron scattering. The thickness of the end plate was10 mm. Both the H2 and O2 gas flow rate was 100 ml/min. Pt/CB was used as a catalyst. For the electrolyte membrane and the binder, QPAF-4(1) was used. The temperature of the cell was 60°C and the humidity was 100% RH.Results and DiscussionFig. 1 shows the water distribution inside the AEMFC parallel to the MEA. In Fig. 1(a), the left side is the anode and the right side is the cathode. In the image, three vertical blue lines are seen. The two outer lines are of a Kapton tape made of silicone. The middle line is of the water on the anode side of the AEMFC. There are blue squares on both side the anode and cathode; the bule squares on the anode side are very clear, whereas those on the cathode side are vague. These blue squares are gas flow channels. The relative thickness of water is represented by the color bar shown on the right in Fig. 1. In the dark area, water hardly existed. As the water increased, the color changed to red. Fig. 1(b) is an enlarged image of the gas flow path and the MEA. In the middle of the image, an MEA (0.55 mm thick) existed with GDLs (anode side 330 µm thick, cathode side 210 µm thick) sandwiching the CCM using a QPAF-4 membrane (30 µm thick). At the cathode, water was hardly imaged, but a small amount of water was observed in the gas flow channels near the outlet, mostly on the wall of flow channel in purple. In the GDL at the cathode, a small amount of water was observed on the CCM. At the anode, water was observed both in the gas flow channel and under the ribs. A larger amount of water was observed in the gas flow channel especially near the outlet, whereas near the inlet, a smaller amount of water was observed in the gas flow channel and under the ribs. In the gas flow channel, a large amount of liquid water was seen on the wall surface of the gas channel of the anode. Therefore, In the gas channel of the AEMFC, the gas path existed on the GDL side. Fig. 2 shows the water distribution inside the AEMFC perpendicular to the MEA. The thickness of liquid water in the gas channel and the entire MEA area at different current densities are calculated. In AEMFC, at low current density, liquid water existed near the outlet of the gas channels. As the current density increases, liquid water was also generated near the ribs and near the inlet of the gas flow channels. In PEMFC (not shown), at low current density, almost no liquid water existed in the gas channel and MEA. As the current density increased, liquid water is generated only near the gas channel outlet. The water distribution trends of PEMFC and AEMFC were significantly different. References Ono et al. J. Mater. Chem. A, 5 (47), 24804-24812 (2017)Shinohara et al., Rev. Sci. Instrum. 91, 043302 (2020). Figure 1

Modulation of response activation leads to biases in perceptuomotor decision making.

Humans are constantly enacting motor responses based on perceptual judgments or decisions. Recent work suggests that accumulating evidence for a decision and planning the action to enact the decision are coupled. Further, decision commitment may occur when the action reaches its motor threshold. Across several experiments, this coupled perception-action account of perceptuomotor decision making was tested by determining if increasing response activation corresponding to one decision influenced the evidence needed to make that decision. Participants were presented with stimuli that contained varying ratios of yellow-to-blue squares and made a speeded left/right-hand response to report whether the stimulus had more yellow or blue squares, respectively. Response activation was modulated by presenting stimuli laterally on the screen-spatially compatible or incompatible with the color reports. When stimuli appeared leftward (spatially compatible with a left response/"yellow" report), the threshold for a "yellow" perceptuomotor decision was reduced-consistent with the hypothesis that increasing "yellow" response activation would lead to a "yellow" reporting bias. Further, when stimuli appeared rightward (spatially compatible with a right response/"blue" report), the threshold for a "blue" perceptuomotor decision was reduced. An additional experiment revealed that directional saccades occurring during the task were unlikely to account for biases. Overall, spatially induced response activation influenced the decision outcomes, providing support for a tightly coupled perception-action system underlying perceptuomotor decisions. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Ancient genome of Empress Ashina reveals the Northeast Asian origin of Göktürk Khanate

Ancient genome of Empress Ashina reveals the Northeast Asian origin of Göktürk Khanate

A Smart Molecule Showing Spin Crossover Responsive Aggregation-Induced Emission

A Smart Molecule Showing Spin Crossover Responsive Aggregation-Induced Emission

Soft Tissue Standardization Improves Humerus Tissue Thickness Precision and Lowers BMD in Total Shoulder Arthroplasty Patients

DXA technology requires soft tissue attenuation measurement. This sampling is confined within a standard soft tissue region of interest (ROI) defined by the blue squares on Figure 1, which is automatically placed and used to compare with radiation absorption over bone. Variable placement of the soft tissue ROI likely alters BMD measurement and reproducibility. The aim of this study was to measure humeral BMD in total shoulder arthroplasty (TSA) patients. As no shoulder feature is available in GE Lunar enCORE v18, hip atypical femur fracture (AFF) software was utilized. In preliminary evaluation, we observed that soft tissue ROI placement and amount of tissue sampled were inconsistent (Figure 2). We hypothesized that use of a consistent soft tissue ROI would change BMD and improve precision. The purpose of this analysis was to compare humerus BMD and precision prior to and following soft tissue ROI standardization. After manufacturer consultation, all scans were reanalyzed using a soft tissue ROI of a fixed size (100 pixels tall, 50 pixels wide) manually placed on every scan distal and lateral to the humeral head (Figure 3). This study of TSA patients, 1-5 years post-surgery, included full humerus scans obtained on a GE Lunar iDXA with v17 or v18 software and analyzed with v18. Each participant had bilateral shoulder scans performed twice to assess precision and humerus BMD was measured at custom ROIs. BMD and tissue thickness obtained with automated and manual approaches were compared using T-test. Precision was determined using the ISCD calculator and compared between methods with F-test. Thirty subjects were included (20M/10F) with mean age and years’ post-surgery of 70.6 and 2.7 respectively. Average tissue thickness was reduced 13.5% (p < 0.01) with manual tissue sampling. Mean BMD among the nine custom ROIs was 2.2-8.5% lower (p < 0.01) with manual tissue sampling (Table 1). Additionally, tissue thickness %CV improved (p < 0.01) from 47.6 to 14.8% and 25.9 to 9.6%. Similarly, BMD precision improved (p < 0.01) at the 1/3 humerus and distal implant ROIs on the TSA side (Table 2). When measuring skeletal sites without optimized software available, it is necessary to critically evaluate software performance. In this study, soft tissue ROI standardization markedly improved tissue thickness sampling and reduced BMD at custom humerus ROIs. Optimization and automation of humerus DXA software would likely further improve BMD precision and measurement.

A Novel Hypertension Management Algorithm Guided by Hemodynamic Data

A Novel Hypertension Management Algorithm Guided by Hemodynamic Data

Efficient Electrocatalytic CO2 Reduction to C2+ Alcohols at Defect-Site-Rich Cu Surface

Summary Electrochemical CO2 reduction is a promising approach for upgrading excessive CO2 into value-added chemicals, while the exquisite control of the catalyst atomic structures to obtain high C2+ alcohol selectivity has remained challenging due to the intrinsically favored ethylene pathways at Cu surface. Herein, we demonstrate a rational strategy to achieve ∼70% faradaic efficiency toward C2+ alcohols. We utilized a CO-rich environment to construct Cu catalysts with stepped sites that enabled high surface coverages of ∗CO intermediates and the bridge-bound ∗CO adsorption, which allowed to trigger CO2 reduction pathways toward the formation alcohols. Using this defect-site-rich Cu catalyst, we achieved C2+ alcohols with partial current densities of > 100 mA·cm−2 in both a flow-cell electrolyzer and a membrane electrode assembly (MEA) electrolyzer. A stable alcohol faradaic efficiency of ∼60% was also obtained, with ∼500 mg C2+ alcohol production per cm2 catalyst during a continuous 30-h operation.

Reliability of 3D Cs2M+M3+X6 type absorbers for perovskite solar cells: assessing the figures of merit

Figures of merit analysis of Cs2M+M3+X6 type absorbers for perovskite solar cells. Specific material properties (blue squares), a few merits (green squares), demerits (red squares) and possible solutions (grey squares) are indicated.

S0152 Successful Bacterial Engraftment Identified by Next Generation Sequencing Following Fecal Microbiota Transplantation for Clostridioides difficile Infection

INTRODUCTION: Fecal Microbiota Transplantation (FMT) has become a standard therapy for toxigenic Clostridioides difficile infection (CDI). In this study we sought to investigate the utility of next generation sequencing (NGS) to characterize the extent of bacterial engraftment following FMT in CDI patients. FMT efficacy was elucidated utilizing metagenomic analyses to identify microbiota similarities among the cohort with that of the healthy Donor’s. METHODS: NGS was performed on fecal samples from study participants (n = 7). Patient stools were collected both prior to and after FMT. From the stool specimens, DNA was extracted, prepared, and sequenced utilizing shotgun methodology on Illumina’s NextSeq 550 System. Metagenomic analyses were performed to characterize the intestinal microbiota of the study participants. RESULTS: Principal Component Analysis (Figure 1) of the microbiota from study participants was executed to investigate the variance among them. PC1 and PC2 captured 52% and 34% of the variation respectively, and clearly highlighted the shift in the patients’ gut flora compared to their microbiota prior to engraftment. The relative abundances (Figure 2) of the bacterial taxa in the samples elucidated the compositional resemblance of Patients 1 and 2 after their FMT with that of their Donor. The pre-FMT relative abundance of Firmicutes in Patient 1 and Patient 2 were 51% and 15%, whereas after FMT they matched closely with the Donor (73%) at 63% and 60%. The 16% in Patient 3 was suggestive of a failed engraftment, as it was not close to that of the Donor. Similarly, Lachnospiraceae in the Donor (15%) matched with the post-FMT of Patient 1 (19%) and Patient 2 (27%), whereas it did not with Patient 3 (0.36%). The Bray-Curtis Distance Matrix (Figure 3) was utilized to profile the overall microbiota from the study participants. The ordination matrix identified the similarity of Patient 1 and 2 post-FMT with that of the Donor (dark blue squares), clustering in distinct coordinates. It also captured that Patient 3 was the most dissimilar among the post-FMT cohort. CONCLUSION: NGS provides a unique opportunity to assess the microbiomes of patients both prior to, and after FMT; and for the evaluation of the bacterial engraftment. Metagenomic characterization of the gut flora, along with monitored care and patient tracking, collectively elucidate the potential of NGS to provide clinical insight and guide outcomes.Figure 1.: Principal Component Analysis (PCA) of the microbiota from the Donor, pre-FMT patients, and post-FMT patients. The samples circled in red highlight the similarity of Patient 1 and 2 following their FMTs with that of their Donor.Figure 2.: Relative abundances (%) of bacteria in stool samples of Donor, post-FMT and pre-FMT samples at the Phylum and Family level.Figure 3.: Bray-Curtis Distance Matrix of the microbiota from Donor, pre-FMT and post-FMT patients. The samples boxed in red highlight the similarity of Patient 1 and 2 following their FMTs with that of their Donor.

Vanadium Transport through Cation and Anion Exchange Membranes

Transport of redox active molecules across the separator in a flow battery represents an important source of inefficiency and electrolyte-imbalance-induced capacity fade [1]. This transport can occur by diffusion, migration, and convection, with driving forces that change as cells are charged and discharged. The negative electrolyte in a vanadium redox flow battery, for example, contains V2+ and V3+ in proportions that depend on state of charge, but these species are absent from the positive side, leading to ever present concentration driving forces for diffusion across the separator. Migration alternately enhances and diminishes crossover since the electric field in the membrane orients in opposite directions during charge and discharge. Finally, hydraulic and osmotic pressure differences between the positive and negative electrolytes cause solvent flow that carries redox ions.Rigorous theoretical treatment of transport across membranes in flow batteries with concentrated-solution theory is complicated by the large number of species. For example, Nafion in a vanadium redox flow battery may contain: V2+, V3+, VO2+, VO2 +, H+, HSO4 -, SO4 2-, H2O, and fixed SO3 - anions (8). The number of multicomponent diffusion coefficients required to characterize a systems is , where n is the number of species present (after accounting for species coupled by rapid chemical equilibrium). The n multicomponent diffusion coefficients define one conductivity, transference numbers or ratios, , and diffusion coefficients of neutral combinations of species. The experimental and theoretical complexities associated with the multicomponent framework when many species are present motivates exploration of the applicability of the simpler, but less generally valid dilute-solution framework. In particular, we seek to understand how well do the relationships between diffusion coefficients, transference numbers, and conductivity predicted by dilute solution theory hold in practical membranes exposed to application-relevant electrolyte solutions? Do transference numbers predicted from conductivity and permeability measurements agree with independently measured values?Figure 1 shows measured transference numbers for the four vanadium ions relevant to flow batteries in N211 and N212 as blue and red squares, respectively. The measurements were made using a cell with three membranes and four flow compartments [2, 3]. Good agreement between the two data sets is apparent. The averages of the N211 and N212 values are plotted as crosses and reported in boxes to the right of the symbols. Transference numbers for V(IV) and V(V) are approximately an order of magnitude lower than transference numbers for V(II) and V(III). The grey squares with blue and red perimeters are the transference numbers calculated from the formula using measured conductivities and permeabilities. The average calculated values are given to the left of the data symbols, to facilitate comparison with the measured values. The measured and calculated transference numbers agree in magnitude, and no systemic differences are evident. The calculated transference number for V(III) appears to be off the experimental trend with one exception: a relatively large transference number is calculated for V(III) because it has a charge number of 3. The disagreement between the measured and calculated transference numbers for V(III) could arise from ion pairing effectively lowering the charge number. The calculated transference numbers are higher for V(II) and V(III) than V(IV) and V(V) because their permeabilities are higher while their conductivity is lower. All these results indicate the value of the study: dilute solution theory accurately predicts transference numbers for all species except perhaps V(III) in Nafion, and this deviation from the model for V(III) may inform the solvated behavior of V(III) ions.AcknowledgementsThis work was supported as part of the Joint Center for Energy Storage Research, an Energy Innovation Hub funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences. The submitted manuscript has been created by UChicago Argonne, LLC, Operator of Argonne National Laboratory (“Argonne”). Argonne, a U.S. Department of Energy Office of Science laboratory, is operated under Contract No. DE-AC02-06CH11357.

Visual acuity and egg spatial chromatic contrast predict egg rejection behavior of American robins.

Color and spatial vision is critical for recognition and discrimination tasks affecting fitness, including finding food and mates, and recognizing offspring. For example, as a counter defense to avoid the cost of raising the unrelated offspring of obligate interspecific avian brood parasites, many host species routinely view, recognize and remove the foreign egg(s) from their nests. Recent research has shown that host species visually attend to both chromatic and spatial pattern features of eggs; yet how hosts simultaneously integrate these features together when recognizing eggs remains an open question. Here, we tested egg rejection responses of American robins (Turdus migratorius) using a range of 3D-printed model eggs covered with blue and yellow checkered patterns differing in relative square sizes. We predicted that robins would reject a model egg if they could visually resolve the blue and yellow squares as separate features, or accept it if the squares blended together and appeared similar in color to the natural blue-green color of robin eggs as perceived by the avian visual system. As predicted, the probability of robins rejecting a model egg increased with greater sizes of its blue and yellow squares. Our results suggest that chromatic visual acuity and viewing distance have the potential to limit the ability of a bird to recognize a foreign egg in its nest, thus providing a limitation to host egg recognition that obligate interspecific avian brood parasites may exploit.

Descriptive Statistics in Medical Research

Related Article, see p 1474KEY POINT: “…the object of statistical methods is the reduction of data. A quantity of data …is to be replaced by relative few quantities which shall adequately represent the whole.” —Sir Ronald Fisher, 1922In this issue of Anesthesia & Analgesia, Meersch et al1 report results of an observational study on the role of vascular adhesion protein (VAP)-1 in the development of acute kidney injury (AKI) after cardiac surgery. The authors are commended for applying a range of descriptive statistics to characterize the patients and appropriately using and clearly reporting these statistics (Figure).Figure.: Excerpt of Table 1 from Meersch et al.1 Nominal (sex) and ordinal (ASA physical status score) data are reported as counts (absolute frequencies) and percentages (relative frequencies). Note that the numerators (counts per category per group: inside red squares) and denominators (total number of patients per group: inside blue squares) are appropriately presented. Quantitative data are reported as the mean (SD)—which is generally preferred to mean ± SD—or as the median with the Q1, Q3 values. ASA indicates American Society of Anesthesiologists; SD, standard deviation.The choice of the most appropriate summary statistic depends on the type and distribution of data. The following data types are distinguished:2 Nominal data have 2 (eg, sex) or more (eg, blood type) nonordered categories. Ordinal data have categories with a logical order (eg, American Society of Anesthesiologists [ASA] physical status score). Interval data are numeric and have an arbitrary zero point (eg, temperature in Celsius), while ratio data have an absolute zero point (eg, weight). Nominal and ordinal data are correctly summarized with the counts (absolute frequencies) and proportions or percentages (relative frequencies) of observations within the categories. When reporting relative frequencies, the numerator and denominator should both be presented. Interval and ratio data can also be summarized by frequencies within specific strata of the quantitative data (eg, number of patients with age 0–10 years, 11–20 years, etc). These frequencies are commonly reported as a histogram, providing a useful visual display of the data distribution. Two key characteristics of an interval or ratio dataset are (a) its central tendency characteristic—the “average” location of the data and (b) its variability—the extent to which individual values vary around the center. Both should be reported. For approximately normally distributed data, the arithmetic mean appropriately describes the center of the data.3 It is the sum of all observed values, divided by the number of observations. The mean is commonly accompanied by the standard deviation (SD), which describes how far the data points are dispersed around the mean. For normally distributed data, 68% are within 1 SD, 95% are within 2 SDs, and >99% are within 3 SDs on both sides of the mean.3 The median is the value that divides a dataset into 2 equal-sized parts, with the same number of datapoints above and below it.3 It is relatively robust to asymmetric (skewed) distributions, and extreme values (outliers). Therefore, the median is preferred to the mean for non-normally distributed data, and it can also be used for ordinal data.3 The median is commonly reported with the first and third quartiles (Q1, Q3), often loosely referred to as interquartile range. Quartiles divide the dataset into4 equally sized parts, and the interval between Q1 and Q3 contains the middle 50% of the data points. Descriptive statistics are also sometimes used as point estimates of population parameters (eg, using a sample to estimate a proportion or a mean in the population). In this case, they should be accompanied by a confidence interval as a measure of the estimate precision.4

Compositional Nature of Language to Represent Bimodal Visual- Audial Percepts

We describe the perceptual domain which have a composition domain and also which is rarely ever captured in the existed system. This has happened because they started to learn the composition structure directly. Compositional structures can be divided into separate domains. Keeping that in mind, we propose another way to deal with demonstrating bimodal perceptual areas that expressly relates unmistakable projections over every methodology and after that mutually learns a bimodal meager portrayal. Presently this model will empower compositionality crosswise over particular projections and sum up to percept's traversed by this compositional premise. For instance, our model can be prepared on red triangles and blue squares; yet, certainly will likewise have learned red squares and blue triangles. To test our model, we have procured another bimodal dataset including pictures and spoken articulations of hued shapes (hinders) in the table top setting.

Earth science education: The current state of play

Earth science education: The current state of play

290: Association between acculturation and preterm birth is not mediated by measures of social stress

Acculturation, a process of changing cultural norms due to acclimation to new or different cultural settings, has been associated with preterm birth (PTB) in the US. We sought to evaluate whether this association may be mediated by social support, resilience, or perceived racism. Secondary analysis of a prospective cohort study of nulliparous women recruited from 8 sites across the US. Degree of acculturation was defined using birthplace and self-rated English competency (see Table 1). Low social support, low partner support, and low resilience were defined as scores in the lowest quartile of the Multidimensional Scale of Perceived Social Support (MSPSS), MSPSS partner support subscale, and Connor-Davidson Resilience scale, respectively. High perceived racism was defined as 3 or more discrimination experiences on the Krieger Racism scale. All women in the cohort were included unless information to determine acculturation was lacking. Univariable analyses assessed the relationship between acculturation and each potential mediator. Next, mediation analyses were conducted via paramed (STATA 14), comparing counterfactual logistic regressions of PTB on strong acculturation and each mediator. The indirect or mediation effect is the change in PTB resulting from changing the value of the mediator (social stressor) while holding acculturation constant. Adjusted direct and indirect effect odds ratios (aORs) are reported (Figure 1). Of 9942 women eligible for analysis, 8102 (81.5%) were strongly acculturated and 1840 (18.5%) were moderately/weakly acculturated. In univariate analyses, moderately/weakly acculturated women reported lower partner support, lower resilience, and higher perceived racism (Table 1). Mediation analyses revealed no effect of these stressors on the relationship between acculturation and PTB, as indicated by non-significant aORs for indirect effects (Figure 1, red circles). Direct effect aORs for strong acculturation remained significant (Figure 1, blue squares), demonstrating an independent association of strong acculturation with PTB. In this group of nulliparous women, higher social stress is more common for weakly/moderately acculturated women. However, the relationship between strong acculturation and increased PTB is not mediated by social stressors. Additional study is needed to identify the mechanisms of this relationship.View Large Image Figure ViewerDownload Hi-res image Download (PPT)

Object-based target templates guide attention during visual search.

During visual search, attention is believed to be controlled in a strictly feature-based fashion, without any guidance by object-based target representations. To challenge this received view, we measured electrophysiological markers of attentional selection (N2pc component) and working memory (sustained posterior contralateral negativity; SPCN) in search tasks where two possible targets were defined by feature conjunctions (e.g., blue circles and green squares). Critically, some search displays also contained nontargets with two target features (incorrect conjunction objects, e.g., blue squares). Because feature-based guidance cannot distinguish these objects from targets, any selective bias for targets will reflect object-based attentional control. In Experiment 1, where search displays always contained only one object with target-matching features, targets and incorrect conjunction objects elicited identical N2pc and SPCN components, demonstrating that attentional guidance was entirely feature-based. In Experiment 2, where targets and incorrect conjunction objects could appear in the same display, clear evidence for object-based attentional control was found. The target N2pc became larger than the N2pc to incorrect conjunction objects from 250 ms poststimulus, and only targets elicited SPCN components. This demonstrates that after an initial feature-based guidance phase, object-based templates are activated when they are required to distinguish target and nontarget objects. These templates modulate visual processing and control access to working memory, and their activation may coincide with the start of feature integration processes. Results also suggest that while multiple feature templates can be activated concurrently, only a single object-based target template can guide attention at any given time. (PsycINFO Database Record

Shorter-lived neural taste representations in obese compared to lean individuals

Previous attempts to uncover a relation between taste processing and weight status have yielded inconclusive results leaving it unclear whether lean and obese individuals process taste differently, and whether group differences reflect differential sensory encoding or evaluative and reward processing. Here, we present the first comparison of dynamic neural processing as assessed by gustatory evoked potentials in obese and lean individuals. Two supra-threshold concentrations of sweet and salty tastants as well as two sizes of blue and green squares were presented to 30 lean (BMI 18.5–25) and 25 obese (BMI > 30) individuals while recording head-surface electroencephalogram (EEG). Multivariate pattern analyses (MVPA) revealed differential taste quality representations from 130 ms until after stimulus offset. Notably, taste representations faded earlier and exhibited a reduced strength in the obese compared to the lean group; temporal generalization analysis indicated otherwise similar taste processing. Differences in later gustatory response patterns even allowed decoding of group membership. Importantly, group differences were absent for visual processing thereby excluding confounding effects from anatomy or signal-to-noise ratio alone. The latency of observed effects is consistent with memory maintenance rather than sensory encoding of taste, thereby suggesting that later evaluative aspects of taste processing are altered in obesity.

Cuttlefish

In this quick guide, Darmaillacq and Osorio introduce the reader to the fascinating biology of the cuttlefish.

Learning Compositional Sparse Bimodal Models.

Various perceptual domains have underlying compositional semantics that are rarely captured in current models. We suspect this is because directly learning the compositional structure has evaded these models. Yet, the compositional structure of a given domain can be grounded in a separate domain thereby simplifying its learning. To that end, we propose a new approach to modeling bimodal perceptual domains that explicitly relates distinct projections across each modality and then jointly learns a bimodal sparse representation. The resulting model enables compositionality across these distinct projections and hence can generalize to unobserved percepts spanned by this compositional basis. For example, our model can be trained on red triangles and blue squares; yet, implicitly will also have learned red squares and blue triangles. The structure of the projections and hence the compositional basis is learned automatically; no assumption is made on the ordering of the compositional elements in either modality. Although our modeling paradigm is general, we explicitly focus on a tabletop building-blocks setting. To test our model, we have acquired a new bimodal dataset comprising images and spoken utterances of colored shapes (blocks) in the tabletop setting. Our experiments demonstrate the benefits of explicitly leveraging compositionality in both quantitative and human evaluation studies.