Biology subjects

Miranda, B.

Publications and source records attributed to Miranda, B..

10 recordsLinked to original sources

bioRxiv2026

Into new depths: climate-driven habitat expansion of the endangered skate Dipturus chilensis (Chondrichthyes, Rajiformes)

The yellownose skate (Dipturus chilensis) is an endangered skate with a narrow distribution in the southeastern Pacific, facing intense fishing pressure and potential climate threats. Using a species distribution model, we projected the current and future distribution of D. chilensis under contrasting climate change scenarios (SSP1-2.6, SSP2-4.5, and SSP5-8.5) for mid-century (2050) and end-of-century (2100). Our models, which demonstrated robust predictive performance significantly better than random expectations, identified maximum temperature and minimum oxygen as the primary environmental drivers of habitat suitability. Projections revealed a consistent poleward range shift towards the Channels and Fjords of Southern Chile ecoregion across all scenarios. While localized habitat loss was projected in Central Chile and Araucanian ecoregions, particularly under high emissions (SSP5-8.5), these losses were outweighed by southern expansions, leading to a net increase in total suitable habitat by 2100. These findings underscore the critical need for climate-adaptive management strategies, including the protection of emerging southern refugia and dynamic fisheries regulations, to ensure the long-term persistence of D. chilensis.

ecology↗

bioRxiv2025

Advancing Mobile Neuroscience: A Novel Wearable Backpack for Multi-Sensor Research in Urban Environments

The rapid global urbanisation has intensified the need to understand the complex interactions and impacts that city environments have on human physical or mental health and well-being. Traditional indoor laboratory-based approaches conduct experiments in well controlled settings but, while advantageous for their controlled conditions, they often lack ecological validity. To address this gap, we present the "eMOTIONAL Cities Walker Backpack" -- a wearable unit developed for synchronously collecting multi-modal data in dynamic real-world settings. Designed for both indoor and outdoor use, the backpack integrates environmental (for microclimate, air pollution and noise) and physiological sensors (including electroencephalography, eye-tracking and wrist-based biosensors for cardiovascular monitoring) to enable the study of human experience in naturalistic urban environments. In this paper, we describe the technical specifications and implementation of this technology during outdoor acquisitions across selected urban locations in the city of Lisbon. We also highlight its potential for methodological comparison with traditional lab-based tasks (particularly through the use of equivalent sensing technologies), and thus advancing the field of translational research in mental health and urban studies.

neuroscience↗

bioRxiv2025

Divergence of Functional Brain Network Configurations in Same and Other Race Face Recognition

The "Other-Race Effect" (ORE) refers to the enhanced memory individuals have for faces within their own racial group compared to other races. This effect is attributed to limited exposure to different races and social-motivational factors affecting face processing. While past research has explored this effect through neuroimaging methods, the precise neural mechanisms that underlie the ORE remain a subject of ongoing investigation. Previous studies have largely adopted a modular perspective, concentrating on the differential activation of face-processing regions when comparing same-race and other-race facial recognition behaviors. However, given the multifaceted nature of the ORE, an exclusive focus on specialized regions may miss the pivotal role played by non-face-preferential brain areas in modulating this phenomenon. In the present study, we take a broader data-driven perspective using graph-theoretical techniques to investigate whole-brain network disparities in same- and other-race facial recognition. Our findings reveal a substantial impact of race on functional connectivity during face memorization. While other-race face recognition benefitted from higher local efficiency during encoding, reduced local efficiency was advantageous for memorization of same-race faces. Notably, successful other-race recognition was disproportionately supported by locally efficient processing in regions among the ventral and dorsal attention networks.

neuroscience↗

bioRxiv2025

Neural signatures of model-based and model-free reinforcement learning across prefrontal cortex and striatum

Animals integrate knowledge about how the state of the environment evolves to choose actions that maximise reward. Such goal-directed behaviour - or model-based (MB) reinforcement learning (RL) - can flexibly adapt choice to changes, being thus distinct from simpler habitual - or model-free (MF) RL - strategies. Previous inactivation and neuroimaging work implicates prefrontal cortex (PFC) and the caudate striatal region in MB-RL; however, details are scarce about its implementation at the single-neuron level. Here, we recorded from two PFC regions - the dorsal anterior cingulate cortex (ACC) and dorsolateral PFC (DLPFC), and two striatal regions, caudate and putamen - while two rhesus macaques performed a sequential decision-making (two-step) task in which MB-RL involves knowledge about the statistics of reward and state transitions. All four regions, but particularly the ACC, encoded the rewards received and tracked the probabilistic state transitions that occurred. However, ACC (and to a lesser extent caudate) encoded the key variables of the task - namely the interaction between reward, transition and choice - which underlies MB decision-making. ACC and caudate neurons also encoded MB-derived estimates of choice values. Moreover, caudate value estimates of the choice options flipped when a rare transition occurred, demonstrating value update based on structural knowledge of the task. The striatal regions were unique (relative to PFC) in encoding the current and previous rewards with opposing polarities, reminiscent of dopaminergic neurons, and indicative of a MF prediction error. Our findings provide a deeper understanding of selective and temporally dissociable neural mechanisms underlying goal-directed behaviour.

neuroscience↗

bioRxiv2024

Convergent genetic adaptation in human tumors developed under systemic hypoxia and in populations living at high altitudes

EPAS1HIF2 is the primary gene implicated in systemic hypoxia adaptation. Conversely, aberrantly activated EPAS1HIF2 acts as a tumor driver against which anti-tumor therapeutics are proven effective. We elucidated connections between adaptation to systemic hypoxia in high-altitude populations, such as Tibetans and Sherpas, and human tumors. Similar to the accelerated adaptability observed in high-altitude populations via genetic introgression, tumors from patients with hypoxia since birth exhibited impaired DNA repair and increased mutation burden. As in high-altitude dwellers, EPAS1HIF2 genetic variants were positively selected within sympathetic tumors developed under hypoxia, with a consistently high frequency of 90%. Bulk and single-cell RNA sequencing followed by in vitro studies have shown that hypoxia and EPAS1HIF2 gain-of-function tumor mutations induce COX4i2 expression and impair mitochondrial respiration, indicating that decreased cellular oxygen consumption may confer a proliferative advantage in hypoxia. Analyzing medical data from a patient cohort with hypoxia since birth who developed/did not develop tumors revealed tissue-specific and time-dependent tumorigenic effects of systemic hypoxia, which is limited to oxygen-sensitive and responsive cells, particularly during the postnatal period. This study supports connections between the EPAS1HIF2 genetic adaptation in human tumors developed under systemic hypoxia to populations living in high altitudes. The genetic adaptations in populations to different stressors can be explored further to understand tumorigenesis and tumor evolution.

cancer biology↗

bioRxiv2024

Functional brain imaging predicts population-level visits to urban spaces

Urbanization is increasing around the world, and urban development strategies focusing on sustainability and the welfare of urban residents are needed. In response to this need, the field of neurourbanism has emerged, which leverages research on the human brain to understand and predict the influence of urban environments. For example, studying brain regions involved in reward processing and value-based decision making, such as the ventromedial prefrontal cortex (vmPFC), may help us understand how people interact with and navigate through urban environments. In this study, we aimed to ascertain whether neural activity within the vmPFC can predict population-level visits around the urban spaces of a city - in our case, Lisbon, Portugal. We used the density of photographs taken around Lisbon as a proxy measure of these visits. To do this, we created a stimulus set featuring 160 images of Lisbon sourced from the social media platform, Flickr. Then, study participants in the U.S. who had never visited Lisbon, viewed these images while we recorded their brain activity. We found that in our sample, activity in the vmPFC predicted the density of photographs taken around Lisbon, and hence, the population-level visits. Our research highlights the crucial role of the brain, especially reward-related brain regions, in shaping human behavior within urban environments. By shedding light on the neural mechanisms underlying urban behavior in humans, our research opens exciting possibilities for the future of urban planning. With this knowledge, policymakers and urban planners can potentially design cities that can promote well-being, social interaction, and sustainable living.

neuroscience↗

bioRxiv2023

Investigations on Antarctic fish IgM drives the generation of an engineered mAb by CRISPR/Cas9

IgM is the major circulating Ig isotype in teleost fish, showing in Antarctic fish unique features such as an extraordinary long hinge region, which plays a crucial role in antibody structure and function. In this work, we describe the replacement of the hinge region of a murine monoclonal antibody (mAb) with the peculiar hinge from Antarctic fish IgM. We use the CRISPR/Cas9 system as a powerful tool for generating the engineered mAb. Then, we assessed its functionality by using an innovative plasmonic substrate based on bimetallic nanoislands (AgAuNIs). The affinity constant of the modified mAb was 2.5-fold higher than the one obtained from wild-type mAb against the specific antigen. Here, we show the suitability of the CRISPR/Cas9 method for modifying a precise region in immunoglobulin gene loci. The overall results could open a frontier in further structural modifications of mAbs for biomedical and diagnostic purposes.

molecular biology↗

bioRxiv2021

Distributional reinforcement learning in prefrontal cortex

Prefrontal cortex is crucial for learning and decision-making. Classic reinforcement learning (RL) theories centre on learning the expectation of potential rewarding outcomes and explain a wealth of neural data in prefrontal cortex. Distributional RL, on the other hand, learns the full distribution of rewarding outcomes and better explains dopamine responses. Here we show distributional RL also better explains prefrontal cortical responses, suggesting it is a ubiquitous mechanism for reward-guided learning.

neuroscience↗

bioRxiv2019

Combined model-free and model-sensitive reinforcement learning in non-human primates

Contemporary reinforcement learning (RL) theory suggests that potential choices can be evaluated by strategies that may or may not be sensitive to the computational structure of tasks. A paradigmatic model-free (MF) strategy simply repeats actions that have been rewarded in the past; by contrast, model-sensitive (MS) strategies exploit richer information associated with knowledge of task dynamics. MF and MS strategies should typically be combined, because they have complementary statistical and computational strengths; however, this tradeoff between MF/MS RL has mostly only been demonstrated in humans, often with only modest numbers of trials. We trained rhesus monkeys to perform a two-stage decision task designed to elicit and discriminate the use of MF and MS methods. A descriptive analysis of choice behaviour revealed directly that the structure of the task (of MS importance) and the reward history (of MF and MS importance) significantly influenced both choice and response vigour. A detailed, trial-by-trial computational analysis confirmed that choices were made according to a combination of strategies, with a dominant influence of a particular form of model sensitivity that persisted over weeks of testing. The residuals from this model necessitated development of a new combined RL model which incorporates a particular credit assignment weighting procedure. Finally, response vigor exhibited a subtly different collection of MF and MS influences. These results provide new illumination onto RL behavioural processes in non-human primates.

neuroscience↗

bioRxiv2017

Triple dissociation of attention and decision computations across prefrontal cortex

Anatomical, neuroimaging and lesion studies indicate that prefrontal cortex (PFC) can be subdivided into different subregions supporting distinct aspects of decision making. However, explanations of neuronal computations within these subregions varies widely across studies. An integrated and mechanistic account of PFC function therefore remains elusive. Resolving these debates demands a rich dataset that directly contrasts neuronal activity across multiple PFC subregions within a single paradigm, whilst experimentally controlling factors such as the order, duration and frequency in which choice options are attended and compared. Here, we contrast neuronal population responses between macaque orbitofrontal (OFC), anterior cingulate (ACC) and dorsolateral prefrontal cortices (DLPFC) during sequential value-guided information search and choice. From the first fixation of choice-related stimuli, a strong triple dissociation of information encoding emerges in parallel across these PFC subregions. As further information is gathered, population responses in OFC reflect an attention-guided value comparison process. Meanwhile, parallel signals in ACC reflect belief updating in light of new evidence, integration of that evidence to a decision bound, and an emerging action plan for which option should be chosen. Our findings demonstrate the co-existence of multiple, distributed decision-related computations across PFC subregions during value-guided choice. They provide a synthesis of several competing accounts of PFC function.

neuroscience↗