Biology subjects

Almeida, J.

Publications and source records attributed to Almeida, J..

At least 19 recordsLinked to original sources

bioRxiv2026

Astrocyte-expressed STAT3 regulates glutamate homeostasis and binge ethanol drinking in mice

Astrocytes play an important role in neuronal health. A critical function of astrocytes is to clear excess extracellular glutamate and prevent excitotoxicity. STAT3 is a transcription factor that promotes astrocyte development and astrocyte reactivity in neurodegenerative diseases and following central nervous system injury. To determine the innate molecular and behavioral functions of adult astrocyte-expressed STAT3 in a non-pathological state, we created conditional Stat3 astrocyte knockout mice (Stat3 aKO) using Stat3flox and the tamoxifen-activated Cre line, Aldh1l1-Cre/ERT2. We measured transcript levels of Gfap, a known STAT3 target gene, and glutamate transporter genes in the medial prefrontal cortex (PFC) of Stat3 aKO. Gfap, Slc1a2 and Slc17a8 transcripts were decreased in the PFC of Stat3 aKO of both sexes. GLT-1 protein, encoded by Slc1a2, was also reduced in the PFC of male Stat3 aKO. We recorded spontaneous excitatory post-synaptic currents (sEPSCs) in male Stat3 aKO and control prelimbic pyramidal neurons and found increased sEPSC amplitude, consistent with a hyper-glutamatergic state due to impaired glutamate clearance. To determine the behavioral consequences of STAT3 depletion in astrocytes, Stat3 aKO were tested for locomotor activity, anxiety-like behavior and binge ethanol consumption, behaviors linked to dysregulation of glutamate homeostasis. Stat3 aKO mice did not differ in locomotor activity or anxiety-like behavior; however, male Stat3 aKO mice consumed significantly less ethanol than controls. These results indicate that STAT3 in adult astrocytes is crucial for maintaining glutamate transporter levels in the adult brain and that astrocytic STAT3 promotes ethanol consumption in male mice. Main pointsO_LIGfap, Slc1a2 and Slc17a8 expression are lower in the cortex of Stat3 astrocyte knockout mice (Stat3 aKO) C_LIO_LIGLT-1 protein is decreased and glutamate neurotransmission is elevated in the cortex of male Stat3 aKO C_LIO_LIMale Stat3 aKO consume less ethanol C_LI

neuroscience↗

bioRxiv2026

Azelaic Acid Exhibits Dual Antimicrobial and Quorum Sensing Inhibitory Activities Against Pathogens: In Vitro Evaluation and Molecular Docking Insights

Pseudomonas aeruginosa is an opportunistic pathogen whose virulence is largely regulated by quorum sensing (QS), making this system an attractive target for anti-virulence therapies. Azelaic acid (AzA), a naturally occurring dicarboxylic acid widely used in dermatology, has not previously been investigated as a QS inhibitor. This study evaluated the antibacterial and anti-virulence activities of AzA against reference strains and multidrug-resistant clinical isolates of P. aeruginosa, together with its preliminary safety profile and potential molecular interactions with key QS proteins. Minimum inhibitory concentrations (MICs) ranged from 250 to 1000 {micro}g/mL. At sub-inhibitory concentrations, AzA significantly reduced the production of pyocyanin, elastase, protease and alginate in a dose-dependent manner without affecting bacterial viability. Molecular docking predicted favorable interactions of AzA with LasI, LasR, PqsD and PqsR, supporting a potential modulation of QS-associated pathways. Chemoinformatic analyses predicted favorable drug-likeness and safety characteristics, while PBMC viability remained above 90% and hemolysis below 4% within the anti-virulence concentration range. In the Tenebrio molitor infection model, AzA significantly increased larval survival and reduced in vivo pyocyanin production in both the reference strain Pa14 and a multidrug-resistant clinical isolate. Collectively, these findings provide the first evidence that AzA attenuates QS-regulated virulence in P. aeruginosa through complementary in vitro, in silico and in vivo approaches while exhibiting a favorable preliminary safety profile. These results support the repositioning of AzA as a promising anti-virulence candidate for the development of adjunctive therapeutic strategies against multidrug-resistant P. aeruginosa infections.

microbiology↗

bioRxiv2026

Grasping at the organization of object knowledge: testing different object-related dimensions as organizational principles of ventral temporal cortex.

In our daily lives we encounter a myriad of things with which we might need to interact as we navigate our environment. Mental representations of these things must be computed and stored in our brains to be manipulated to support cognition. How are such representations organized in the brain? Several proposals have been put forth on what the principles of organization of object information in the brain might be: within ventral temporal cortex - regions thought to support object recognition - possible dimensions include the animacy status of target stimuli, their real size, their texture and material properties, and potentially their graspable status, amongst others. Here we used functional magnetic resonance imaging (fMRI) and multivariate approaches to discriminate patterns of activation for different categories of objects to test the role of these dimensions as organizing principles of object information in the brain. We show that pattern discriminability between different categories of objects does not seem to follow differences in their animacy status in any continuous way. Moreover, graspability of the target stimuli and their haptic texture properties are better predictors of representational content within ventral temporal cortex than animacy and real size. These results are in line with recent studies demonstrating the importance of computational contingencies superimposed by bi-directional functional coupling between parietal regions dedicated to the processing of object manipulation and grasping and ventral temporal regions responsible for object recognition, potentially involving material and texture processing.

neuroscience↗

bioRxiv2025

Liver Zonation Disruption Fuels Hepatocellular Carcinoma in Chronic Liver Disease

Hepatocellular carcinoma (HCC) arises almost exclusively in chronic liver disease (CLD), yet the classical etiological drivers of injury insufficiently explain why only a subset of patients progress to cancer. Here, we identify disruption of liver metabolic zonation, specifically, aberrant expansion of {beta}-catenin activity from pericentral to periportal territories as a previously unrecognized tumorigenic risk state that emerges across etiologically diverse CLDs. Using spatial transcriptomics and immunohistochemistry from murine liver disease followed by human sample validation, we demonstrate that MASLD/MASH, alcohol-associated hepatitis, viral hepatitis, and immune-mediated cholangiopathies share a striking periportal induction of pericentral {beta}-catenin target programs, indicating a conserved zonation disturbance independent of disease etiology. Since {beta}-catenin expansion occurs alongside inflammation, fibrosis, and metabolic dysfunction in human CLD, its direct oncogenic contribution remained unclear. To functionally isolate the tumorigenic consequence of zonation disruption itself from these confounding disease processes, we employed hepatocyte-specific deletion of ZNRF3 and RNF43--negative regulators that physiologically restrict {beta}-catenin to the pericentral zone. Lineage tracing demonstrates that ZNRF3/RNF43 deletion drives selective periportal hepatocyte proliferation, zonal reprogramming, and tumor initiation in a {beta}-catenin-dependent manner, establishing zonation disruption as a direct mechanistic driver of carcinogenesis. The resulting tumors exhibit a distinct metabolic and immunologic phenotype, including heightened mitochondrial respiration, preserved periportal identity, and T-cell competence, and correspond to a molecularly defined subset comprising 5-10% of human HCCs. Together, these findings reveal {beta}-catenin zonation expansion as a conserved and previously unrecognized HCC risk factor that mechanistically links chronic liver injury to malignant transformation. They further establish ZNRF3/RNF43 deletion as a tractable model of zonation-driven hepatocarcinogenesis and identify a distinct human HCC subtype with unique therapeutic vulnerabilities, opening new avenues for mechanism-based risk stratification, early detection and preventive therapeutic strategies in patients with chronic liver disease.

cancer biology↗

bioRxiv2025

Subliminal beauty engages the brain's valuation circuits

Neuroeconomic models propose that the anterior ventral striatum (aVS) and ventromedial prefrontal cortex (vmPFC) are key regions for computing subjective value (SV) signals that guide choice. However, the role of conscious awareness in this process remains debated. Here we examined whether SV can be automatically computed in these regions without conscious awareness. In an fMRI experiment, participants viewed faces that varied in attractiveness under three conditions: (i) suppressed from awareness via continuous flash suppression (CFS), (ii) clearly visible without suppression, or (iii) absent (background only) with CFS. Participants reported trial-wise facial identity (objective) and visibility (subjective) measures of facial awareness. In a post-fMRI session, they rated the attractiveness of each face as a measure of SV. When faces were seen, task performance (d) exceeded chance and responses were faster than in absent trials. When faces were unseen, performance was at chance but responses were slower than absent trials. Neurally, seen and unseen faces elicited greater neural signal than absent trials and showed similar neural patterns in the fusiform face area (FFA). Critically, neural signal in vmPFC correlated with SV for both seen and unseen faces, with similar neural patterns. In aVS, SV-related signal was only observed for unseen faces. Furthermore, mean face-related signal in FFA correlated with SV-related signals in aVS and vmPFC for unseen faces. These findings demonstrate that SV can be automatically computed in aVS and vmPFC without conscious awareness, suggesting a neural pathway by which subliminal information can influence value-based choice.

neuroscience↗

bioRxiv2025

Leishmania amazonensis amastigotes invade non-phagocytic cells via highly localized parasite-induced actin remodeling.

Intracellular parasites are pathogens that must invade and persist within host cells. In the case of Leishmania spp., it is generally assumed that the parasite must be phagocytosed to further establish residence within professional phagocytic cells. However, several studies report the presence of Leishmania spp. in non-phagocytic cells, highlighting their ability to enter cells independently of classical phagocytosis. Indeed, we have recently demonstrated that promastigotes, the infective form transmitted to hosts during the bite of the insect vector, subvert a lysosome-exocytosis-dependent membrane repair pathway to invade fibroblasts. Here, we investigate the invasion of non-phagocytic cells by L. amazonensis amastigotes, the infective form directly responsible for host-to-vector transmission, disease generation and parasite dissemination during infection in humans and other mammalian hosts. Our results show that amastigotes rapidly induce their entry into cells lacking classical phagocytic capability, where they survive, multiply, and persist. Invasion depends on parasite-induced actin remodeling confined to the parasite-host plasma membrane contact site, with localized recruitment of Rho GTPases that fuel actin polymerization at invasion foci. Our findings highlight the remarkable ability of Leishmania amastigotes to induce their own internalization into virtually any cell type, bypassing the need for conventional phagocytosis. This property may profoundly influence parasite biology by enabling amastigotes to cross cellular barriers, disseminate, and silently establish infection in diverse host cells. Importantly, when considering non-phagocytic cells, our results demonstrate that Leishmania amazonensis employs distinct, stage-specific invasion mechanisms: promastigotes co-opt host cell lysosomes, whereas amastigotes depend on F-actin dynamics. SUMMARYHere we elucidate key aspects of the mechanism by which Leishmania amazonensis amastigotes invade non-phagocytic cells.

microbiology↗

bioRxiv2025

Targeting ZNRF3 and RNF43 to Restore Regeneration and Reverse Metabolic Dysfunction-Associated Steatotic Liver Disease

Liver regeneration and hepatocyte metabolic identity are disrupted in metabolic dysfunction-associated steatotic liver disease (MASLD) and its advanced form, metabolic dysfunction-associated steatohepatitis (MASH), yet the mechanisms of restore liver regeneration and reprogram metabolism for disease reversal remains poorly understood. Here, we show that {beta}-Catenin activity progressively declines in hepatocytes during MASH in both humans and mice, coinciding with impaired regeneration and defective lipid clearance. Targeted deletion of the endogenous WNT pathway inhibitors ZNRF3 and RNF43 in hepatocytes after MASH onset reactivates {beta}-Catenin signaling, leading to robust regression of steatosis, inflammation, and fibrosis, and restoring regenerative capacity across multiple fatty liver disease models. Mechanistically, this therapeutic effect is driven by {beta}-Catenin-dependent induction of the alternative bile acid synthesis pathway without disrupting systemic lipid homeostasis. Importantly, both short-and long-term deletion of ZNRF3/RNF43 restores liver function without triggering tumorigenesis or hepatotoxicity, indicating a safe therapeutic window. These findings reveal that physiological activation of WNT/{beta}-catenin signaling via ZNRF3 and RNF43 offers a viable regenerative and metabolic strategy for reversing fatty liver disease.

cell biology↗

bioRxiv2025

Subliminal risk influences subjective value in the ventromedial prefrontal cortex

The relationship between conscious awareness and decisions has been heavily debated. Here we investigated whether subliminal probabilities are integrated with conscious rewards to form subjective value (SV) representations in the anterior ventral striatum (aVS) and ventromedial prefrontal cortex (vmPFC). Participants played an incentivized competitive game with risky choice to accumulate points across trials in a behavioral and fMRI experiment. The game was a modified attentional-blink paradigm that rendered a probability cue unseen (indicating a 100% or 0% chance to win a risky reward). Following the probability cue, participants chose between a safe (1 point with certainty) or risky option (>1 or 0 points depending on probability cue). The risky reward was either 2 or 5 points, varying across trials. In some trials the probability cue was absent (replaced by a random distractor) and the probability to win the risky reward was 50%. When probability cues were unseen, they did not influence choice, as value-maximizing choice (d) was not greater than chance, but they did influence reaction time in both experiments. Consistent with SV integration, the BOLD signal in aVS and vmPFC was higher for both conscious rewards (high > low) and subliminal probabilities (high > low) and could not be explained by subliminal salience (cue present > absent). Moreover, multivariate pattern similarity between conscious rewards and subliminal probabilities in vmPFC suggest integration into an abstract value representation. Additionally, we found brain-wide subliminal probability and salience effects. Taken together, these results suggest that conscious awareness is not necessary for probability to be integrated with conscious rewards to form an abstract "common currency" SV representation in vmPFC. Additionally, brain-wide subliminal probability and salience effects suggests information can have "global access" without conscious awareness.

neuroscience↗

bioRxiv2024

Effect of curcumin and 5-bromoindole-3-carboxyaldehyde on the inhibition of Quorum sensig-dependent virulence factors in Pseudomonas aeruginosa

Curcumin and 5-bromoindole-3-carboxaldehyde were tested for their ability to inhibit quorum sensing-dependent virulence factors in Pseudomonas aeruginosa strains Pa01, Pa14, and ATCC 27853. The compounds were evaluated at curcumin (1, 5 g/ml) and 5-bromoindole-3-carboxaldehyde (30, 50, 100 g/ml). Virulence factors--exoprotease, elastase, pyocyanin, and alginate --were measured. Chemoinformatics properties were analyzed using Molinspiration, Molsoft, Osiris Property Explorer, pkCSM, and SwissADME. Results showed 5-bromoindole-3-carboxaldehyde significantly reduced pyocyanin in Pa01 (92.5% at 100 g/ml), elastase (79.85% at 100 g/ml), exoprotease (92.8% at 50 g/ml), and alginate in ATCC 27853 (76.16% at 100 g/ml). Curcumin effectively inhibited pyocyanin in ATCC 27853 (100% at 5 g/ml), elastase in Pa14 (56.19% at 5 g/ml), exoprotease in Pa01 (87.04% at 5 g/ml), and alginate (48.26% at 5 g/ml). Both compounds demonstrated strong inhibition of virulence factors, suggesting their potential as anti-virulence agents against P. aeruginosa, a highly resistant bacterium prevalent in nosocomial infections.

microbiology↗

bioRxiv2024

Guidelines for evaluating the success of large carnivore reintroductions

Anthropogenic impacts have led to widespread species decline and extirpation, thereby compelling a global movement to protect and regenerate biodiversity through holistic ecosystem restoration including reintroductions. Yet, despite the increasing practice of conservation-driven reintroduction efforts over the past century, peer-reviewed literature and policy providing criteria with which to evaluate reintroduction stages and efficacy remain limited. Without these comprehensive and quantifiable metrics of relative success, such drastic conservation intervention strategies cannot be objectively evaluated nor compared, hindering the advancement of restoration as a discipline. Herein, we systematically reviewed 227 large carnivore reintroductions of 14 terrestrial mammal species across 23 countries since 1930 to contextualize global efforts to date, and from these, have developed a standardized framework to evaluate reintroduction success. We further retrospectively determined the extent to which existing studies met these criteria towards identifying current knowledge gaps and guide future reintroduction efforts. Most large carnivore records were of Felidae (70%) reintroduced into closed systems (69%) across southern Africa (70%). Our proposed framework provides a full suite of stages, indicators, and targets for reintroduction evaluation, which, when retrospectively applied to reviewed studies, indicated that at least one-third lacked sufficient information to effectively evaluate and compare reintroduction outcomes. This comprehensive and prioritized framework provides novel transparency and scalability to large carnivore reintroduction programs, which is increasingly required to secure the sustained support of impacted communities and stakeholder networks. Moreover, the incorporation of this framework into future practice and policy as an applied tool may directly benefit the recovery of at least 30 large carnivore species, while its principles may be applied more broadly across taxonomic groups for faunal rewilding and global ecosystem restoration.

ecology↗

bioRxiv2024

Neural and behavioral similarity-driven tuning curves for manipulable objects

In our daily activities, we encounter numerous objects that we successfully distinguish and recognize within a fraction of a second. This holds for coarse distinctions (e.g., cat vs. hammer) but also for more challenging within-category distinctions that require fine-grain analysis (e.g., cat vs. dog). The efficiency of this recognition depends on how the brain organizes object-related information. While several attempts have focused on unravelling large-scale organization principles, research on within-category organization of knowledge is rather limited. Here, we explored the fine-grain organization of object knowledge and investigated whether manipulable objects are organized and represented in terms of their similarity. To accomplish this, different groups of individuals participated in a behavioral and fMRI release from adaptation experiment. Adaptation was induced by presenting different exemplars of a particular object, and release from adaptation was elicited by the presentation of a deviant object. The relationship between adaptation and deviant objects was manipulated into four levels of similarity, measured by feature overlap between these objects. Our findings revealed that increasing object similarity provoked progressively slower reaction times and progressively weaker fMRI release from adaptation. Specifically, we identified similarity-driven tuning curves for the release from adaptation in the medial fusiform, collateral sulcus, parahippocampal gyri, lingual gyri, lateral occipital complex, and occipito-parietal cortex. These results suggest that the processing and representation of objects in the brain and our ability to perform fine discriminations between objects reflect real-world object similarity in a relatively parametric manner.

neuroscience↗

bioRxiv2024

fMROI: a simple and adaptable toolbox for easy region-of-interest creation

This study introduces fMROI, an open-source software designed for creating regions-of-interest (ROIs) and visualizing magnetic resonance imaging data. fMROI offers a user-friendly graphical interface that simplifies the creation of complex ROIs. It is compatible with various operating systems and enables the integration of user-specified algorithms. Comparative analysis against popular neuroimaging software demonstrates the feasibility, applicability, and ease of use of fMROI. Notably, fMROIs interactive graphical interface with a real-time viewer allows users to identify inconsistencies and design more accurate ROIs, saving significant time by avoiding errors before storing ROIs as NIfTI files. Additionally, fMROI supports automation through command-line accessibility, making it ideal for large-scale analyses. As an open-source platform, fMROI provides a valuable resource for researchers in the neuroimaging community, facilitating efficient ROI creation and streamlining neuroimage analysis.

neuroscience↗

bioRxiv2024

Population estimates of shorebirds on the Atlantic Coast of southern South America generated from large-scale, simultaneous, volunteer-led surveys

Population abundance and trend estimates are crucial to science, management, and conservation. Shorebirds, which are abundant in many coastal habitats and play important roles in coastal ecosystems, are facing some of the most dramatic population declines of any group of birds globally. However, accurate and up-to-date population estimates are lacking for most shorebird species. We thus conducted comprehensive, simultaneous, and community scientist-led surveys of the entire Atlantic Coast of southern South America -- stretching from central Brazil to Tierra del Fuego -- to gather counts of shorebirds that we combined with remote sensing analyses and two-step hurdle models that accounted for presence and abundance. Our objectives were to estimate shorebird densities by habitat, identify high-concentration areas, understand the environmental factors affecting their distributions, and provide population estimates for both Nearctic and Neotropical species. We counted a total of 37,207 shorebirds of 17 species and, from those counts, estimated that nearly 1.1 million shorebirds use the regions coastline. We also found that shorebirds occurred in the highest densities in shallow water wetland habitats and that fewer shorebirds occupied areas that were further away from estuaries. Although not directly comparable, our results suggest the population sizes of the Nearctic species whose nonbreeding ranges are predominantly in southern South America may have declined substantially since previous estimates. At the same time, our study represents the first empirically derived population estimates for Neotropical breeding shorebird species and indicates that they are far more abundant than previously thought. Taken together, our results highlight the power of community scientists to carry out structured protocols at continental scales and generate critical data for a group of at-risk species.

ecology↗

bioRxiv2023

Contentopic mapping in ventral and dorsal association cortex: the topographical organization of manipulable object information

Understanding how object information is neurally organized is fundamental to unravel object recognition1-4. The best-known neural organizational principle of information is topographical mapping of specific dimensions. Such maps have been shown mainly for sensorimotor information within sensorimotor cortices (e.g., retinotopy)5-9. Thus, here we ask whether there are topographic maps - by analogy, contentopic maps - for mid-level object-related dimensions. We used functional magnetic resonance imaging and population receptive field analysis7 to measure tuning of neural populations to selected manipulable object-related dimensions. Here we show maps in dorsal and ventral occipital cortex that code for the score of each object on each target dimension in a linear progression following a particular direction along the cortical surface. Maps for each dimension are distinct, and consistent across individuals. Thus, object information is coded in multiple topographical maps - i.e., contentopic maps. These contentopic maps refer to intermediate level visual and visuomotor representations, and are potentially computed from the grouping of lower-level information through non-linear transformation following gestalt principles4,10. This shows that topography is a widespread and non-incidental strategy for the organization of information in the brain that leads to greatly reduced connectivity-related metabolic costs and fast and efficient readouts of information for stimuli discrimination11,12.

neuroscience↗

bioRxiv2023

High capacity of Brazilian Aedes aegypti populations to transmit a locally circulating lineage of Chikungunya virus

The global incidence of chikungunya has surged in recent decades, with South America, particularly Brazil, experiencing devastating outbreaks. The primary vector for transmitting CHIKV in urban areas is the mosquito species Aedes aegypti, which is very abundant in Brazil. However, little is known about the impact of locally circulating CHIKV genotypes and specific combinations of mosquito populations on vector competence. In this study, we analyzed and compared the infectivity and transmissibility of a recently isolated CHIKV-ECSA lineage from Brazil among four Ae. aegypti populations collected from different regions of the country. When exposed to CHIKV-infected mice for blood feeding, all mosquito populations showed high infection rates and dissemination efficiency. Moreover, using a mouse model to assess transmission rates in a manner that better mirrors natural cycles, we observed that these populations exhibit highly efficient transmission rates of CHIKV-ECSA. Our findings underscore the robust capability of Brazilian Ae. aegypti populations to transmit the locally circulating CHIKV-ECSA lineage, potentially explaining its higher prevalence compared to the Asian lineage also introduced in Brazil. Author SummaryChikungunya virus (CHIKV) is an alphavirus transmitted by mosquitoes, gaining attention due to its rapid global spread and public health impact. Initially isolated in Tanzania in 1952, it was confined to Africa, Asia, and the Indian subcontinent. Local transmission of CHIKV in the Americas began in December 2013, leading to a 2014 epidemic. The Aedes aegypti mosquito, prevalent in Brazil, is suspected as the primary vector. Yet, our understanding of how different mosquito populations and virus lineages impact spread is limited. In this Brazilian study, we collected mosquitoes from four regions, exposing them to the local African ECSA lineage of CHIKV. Remarkably, all mosquito populations exhibited high infection rates and efficient virus transmission to vertebrate hosts. This research sheds light on why the ECSA chikungunya lineage is spreading rapidly in Brazil. The Brazilian Ae. aegypti mosquitoes appear to possess exceptional capabilities in transmitting African ECSA lineage of CHIKV, potentially contributing to its rapid dissemination within the country and neighboring regions. Comprehending these dynamics is vital for developing strategies to control and mitigate the impact of chikungunya in affected areas.

immunology↗

bioRxiv2023

Semantic feature production norms for manipulable objects

Feature generation tasks and feature databases are important for understanding how knowledge is organized in semantic memory, as they reflect not only the kinds of information that individuals have about objects but also how objects are conceptually parse. Traditionally, semantic norms focus on a variety of object categories, and, as a result, have a small number of concepts per semantic category. Here, our main goal is to create a more finely-tuned feature database exclusively for one category of objects - manipulable objects. This database contributes to the understanding of within-category, content-specific processing. To achieve this, we asked 130 participants to freely generate features for 80 manipulable objects, and another group of 32 participants to generate action features for the same objects. We then compared our databases with other published semantic norms and found high structural similarity between them. In our databases, we calculated the similarity between visual, functional, encyclopedic, and action feature types. We discovered that objects were grouped in a distinctive and meaningful way according to feature type. Finally, we tested the validity of our databases by asking three groups of participants to perform a feature verification task while manipulating production frequency. Our results demonstrate that participants can recognize and associate the features of our databases with specific manipulable objects. Participants were faster to verify high-frequency features than low-frequency features. Overall, our data provide important insights into how we process manipulable objects and can be used to further inform cognitive and neural theories of object processing and identification.

neuroscience↗

bioRxiv2023

The neural organization of visual information in the auditory cortex of the congenitally deaf

Neuroplasticity is the ability of the human brain to reorganize and modify its activity throughout life. In congenital deafness, sensory-deprived cortex can be recruited to represent sensory information belonging to other modalities, a process known as cross-modal plasticity. Previous studies have indicated that the auditory cortex of congenitally deaf, but not of hearing individuals, is recruited during visual tasks. However, it is not clear to what extent, and how, these cross-modal responses in the deprived auditory cortex represent low-level visual spatial information or map the visual field. Here, we addressed this question directly in an fMRI case-study, aiming to map retinotopic features in the auditory cortex. Two congenitally deaf and one hearing participant went through a conventional retinotopy fMRI experiment with visual stimuli designed to map the visual system. Using population receptive field (pRF) modelling, we revealed retinotopic-related responses in the auditory cortex of the deaf, but not in the hearing. These responses, that were mostly lateralized to the right hemisphere, represented the contralateral visual field, and were characterized by large receptive fields, centred to near foveal areas. Interestingly, we found that these responses to visual stimuli predominantly reflected negative BOLD signals in the auditory cortex of the deaf, suggesting that visual information might be represented through cross-modal deactivation signals.

neuroscience↗

bioRxiv2023

Neural and behavioral signatures of the multidimensionality of manipulable object processing.

Understanding how we recognize everyday objects requires unravelling the variables that govern the way we think about objects and the way in which our representations are organized neurally. A major hypothesis is that the organization of object knowledge follows key object-related dimensions, analogously to how sensory information is organized in the brain. Here, we explored, behaviorally and neurally, the multidimensionality of object processing. We focused on within-domain object information as a proxy for the kinds of object decision tasks we typically engage in our daily lives - e.g., identifying a knife from other types of manipulable objects such as spoons, axes or screwdrivers. To do so, we extracted object-related dimensions from subjective human judgments on a set of objects from a particular object domain - i.e., manipulable objects. We demonstrated that the extracted dimensions are cognitively interpretable - i.e., participants are able to label them; are cognitively relevant for manipulable object processing - i.e., categorization decisions are guided by these dimensions; and are important for the neural organization of knowledge - i.e., they are good predictors of the neural signals elicited by manipulable objects. This shows that multidimensionality is a hallmark of the organization of object knowledge in the brain.

neuroscience↗