Biology subjects

Gopal, A.

Publications and source records attributed to Gopal, A..

At least 19 recordsLinked to original sources

bioRxiv2026

Ebola virus exploits host lncRNA LINC01740 to enhance ATF3 and suppress antiviral immune responses

Ebola virus (EBOV) infection causes severe hemorrhagic fever marked by dysregulated cytokine production, impaired antiviral defenses, and multi-organ failure. Macrophages are primary targets of EBOV, and viral replication profoundly alters macrophage transcriptional programs, driving hyperinflammation. Although long non-coding RNAs (lncRNAs) are increasingly recognized as regulators of immunity and viral pathogenesis, their roles in EBOV infection remain poorly understood. We performed comprehensive transcriptomic profiling of primary human monocyte-derived macrophages infected with the highly pathogenic EBOV Mayinga variant. Infection triggered extensive remodeling of both coding and non-coding transcriptomes, including hundreds of differentially expressed lncRNAs. Functional analysis of neighboring protein-coding genes of EBOV-induced lncRNAs (EVILs) revealed enrichment of pathways linked to cytokine signaling, transcriptional regulation, and cell signaling, all of which are central to Ebola virus disease (EVD) pathogenesis. Among the most strongly induced EVILs, LINC01740 and its neighboring protein-coding gene, Activating Transcription Factor 3 (ATF3), were significantly upregulated. Antisense oligonucleotide-mediated inhibition of LINC01740 reduced ATF3 mRNA and protein levels. CRISPR/Cas13d-mediated knockdown of ATF3 restored type I interferon (IFN-I) signaling and antiviral gene expression in EBOV-infected macrophages. Mechanistically, ATF3 functions as a negative regulator of IFN-I and type I interferon-stimulated gene expression, thereby suppressing antiviral immune responses in EBOV-infected macrophages. Together, these findings identify a previously unrecognized LINC01740-ATF3-IFN-I regulatory axis that EBOV exploits to promote immune suppression and viral replication.

immunology↗

bioRxiv2026

Eukaryotic tRNA ligases mediate RNA break repair

RNA is continuously exposed to damage during physiological metabolism and stress, yet cellular responses to RNA damage remain less understood than DNA repair pathways. RNA strand breaks are particularly deleterious because they generate chemically incompatible RNA ends. Eukaryotic tRNA ligases have been implicated in RNA processing and repair, but whether they function as general RNA repair enzymes remains unresolved. Here, we show that the evolutionarily divergent tRNA ligases, human RTCB and fungal Trl1, mediate RNA break repair (RBR) targeting ribosomes and other ribonucleoprotein (RNP) complexes. Using direct RNA nanopore sequencing, we map these repair events at nucleotide resolution, demonstrating that tRNA ligases repair breaks in ribosomal RNA and restore translational activity of repaired ribosomes. We further identify repair across additional structured cellular RNAs. We show that loss of RBR activity leads to RNA fragmentation in human cells and impairs cell viability upon oxidative stress. Together, these findings uncover a broader role for eukaryotic tRNA ligases in repairing RNA breaks and maintaining transcriptome integrity.

biochemistry↗

bioRxiv2026

Frugivore species richness influences dietary specialisation and network properties in Asian wet tropical forests

AimTo examine how variation in frugivore species richness influences dietary specialisation and the organisation of plant-frugivore interaction networks in tropical forests. LocationSix undisturbed lowland wet tropical forest sites across four biodiversity hotspots in south and south-east Asia. Time period2016-2024. Major taxa studiedAvian frugivores and fleshy-fruited woody plants. MethodsWe recorded plant-avian frugivore interactions across six undisturbed evergreen forest sites spanning a seven-fold gradient in frugivore species richness, while holding forest type and phylogenetic composition broadly comparable. Using over 4,200 hours of focal observations on 551 fruiting plants, we recorded more than 34,000 feeding visits by 138 frugivore species on 133 plant species. We used a) Joint species distribution models to determine the relative influence of fruit and seed traits, and b) network analyses to evaluate how dietary breadth and network properties varied with frugivore species richness. ResultsAcross sites, frugivore visitation was primarily explained by fruit and seed morphology, with seed size accounting for an average of 39.7% of explained variation, followed by fruit width (24.4%), fruit crop size (21.9%), and pulp lipid content (14.1%). Frugivores in species-rich communities exhibited narrower dietary breadth (Pearsons r = -0.87 between normalised degree and species richness). Correspondingly, plant-frugivore networks became less connected and nested, and more modular, with increasing frugivore richness (Pearsons r = -0.9, -0.98, and 0.84, respectively). Main conclusionsIncreasing frugivore species richness intensifies dietary specialisation, which in turn drives changes in plant-frugivore network structure. These findings highlight how local species richness shapes interaction networks through changes in consumer niche breadth, with implications for the organisation of tropical forest mutualistic communities.

ecology↗

bioRxiv2025

Comparing the genetic diversity of two threatened Rhyticeros hornbill species with contrasting geographic range sizes

Island endemics exhibit low genetic diversity due to founder effects and geographical isolation, increasing their vulnerability to inbreeding depression. The Narcondam Hornbill (Rhyticeros narcondami), restricted to the 6.8 km2 Narcondam island in the Andaman archipelago, has the smallest range size among hornbills, a globally threatened group of birds. We compared the genetic diversity of the Narcondam Hornbill with the Wreathed Hornbill (Rhyticeros undulatus) distributed from the Eastern Himalaya to Bali. We generated DNA sequences for four mitochondrial markers ; Cytochrome B (Cytb), cytochrome c oxidase subunit I (COI), NADH dehydrogenase subunit 2 (ND2) and displacement loop (D-loop) regions) from 14 Narcondam Hornbill faecal samples and for three markers (Cytb, COI and ND2) from 19 Wreathed Hornbill tissue samples from north-east India. Our results suggest markedly lower genetic diversity in the island endemic Narcondam Hornbill compared to the Wreathed Hornbill. Specifically, Cytb and COI showed no genetic variation in the island endemic, compared to three to five haplotypes in the Wreathed Hornbills. In the ND2 region, Narcondam Hornbills showed seven haplotypes among 13 samples compared to the Wreathed Hornbills six haplotypes among eight samples. The observed genetic diversity in the D-loop in the Narcondam Hornbill was lower than other island-endemic hornbill species in the Philippines. The extremely low genetic diversity in the Narcondam Hornbill likely stems from a small founder population and/or past hunting pressures that reduced its numbers to approximately 30% of its current population of 1000 birds, rendering the Narcondam Hornbill susceptible to environmental and human-driven changes.

genetics↗

bioRxiv2025

Retrograde Optogenetics Reveals Functional Convergence within a Corticotectal Pathway of Non-Human Primates

Understanding how the cerebral cortex communicates with subcortical areas to drive behavior remains a central question in system neuroscience. One key unresolved issue is whether prefrontal cortical outputs to motor-related subcortical regions carry predominantly motor commands or mixed sensory-motor signals. Retrograde optogenetics offers a powerful way to interrogate such projection-defined circuits, but its use in non-human primates has been limited. Here, we applied retrograde optogenetics in awake macaques to directly test the functional organization of the corticotectal projection from the frontal eye field (FEF) to the superior colliculus (SC). We asked whether the FEF output signals to SC are motor-dominant or broadly sensory-motor. Optical activation of this pathway evoked robust, contralateral saccades and selectively modulated reaction times, demonstrating its causal role in saccade generation. Optogenetically tagging FEF neurons projecting to SC revealed a heterogeneous population of visual, visuomotor, and motor neurons. This diverse output converged predominantly onto motor-related neurons in the SC. These findings support a visuomotor convergence model, in which diverse FEF outputs drive motor-selective SC neurons with activity sufficient for saccade generation, and thus resolve long-standing questions over the composition of FEF outputs. Additionally, our results establish retrograde optogenetics as a tool for dissecting projection-defined circuits in primates and for precisely probing the neural pathways that link perception to action. HighlightsRetrograde optogenetics enabled pronounced and selective modulation of behavior in macaques. Selective optical stimulation of the FEF-SC pathway evoked contralateral saccades and modulated reaction times. Opto-tagging revealed diverse visual, visuomotor, and motor FEF outputs converging onto motor-related SC neurons. Findings support a visuomotor convergence model and demonstrate the power of projection-specific optogenetic tools in primates.

neuroscience↗

bioRxiv2025

Distribution patterns of two widespread, co-dominant savanna tree species of the Indian subcontinent under current and future climates

Future climate is expected to alter the dynamics and distribution of vegetation. Here, we use ecological niche modelling to investigate the current and predicted future distributions of two dominant tree species that characterize the ecology and dynamics of the widespread tropical dry biomes of the Indian subcontinent- Terminalia anogeissiana (formerly and henceforth Anogeissus latifolia) and Terminalia elliptica (both Combretaceae). Using current occurrence data and six ecologically relevant climate variables, we find that, as expected, T. elliptica and A. latifolia share highly similar climatic niches with substantial overlap ([~]84%). Mean annual precipitation (MAP), mean temperature of the driest quarter (MTDQ), and temperature annual range (TAR) emerge as the key environmental variables explaining the distribution of both species, but their relative influence differs. T. elliptica appears to occur across a broader climatic niche that includes wetter areas with cooler dry seasons (lower MTDQ) and lower temperature annual ranges (TAR) relative to A. latifolia. Currently, the area of modelled suitable habitat for both species are vast (A. latifolia: 416,057 km{superscript 2}; T. elliptica: 401,544 km{superscript 2}). However, under future climate scenarios, both species are projected to incur dramatic losses of suitable habitat (A. latifolia: [~]63% by 2041-2060 and [~]84% by 2081-2100; T. elliptica: [~]57.8% by 2041-2060 and [~]73% by 2081-2100). By 2100, the Western Ghats are projected to remain as the last key refugia for both species, while vast other regions are likely to become increasingly unsuitable. Contrary to current understanding, our results underscore the high vulnerability of currently dominant tree species of the tropical dry biomes, through potential losses of suitable habitats under future climate regimes.

ecology↗

bioRxiv2025

Multiple groups of neurons in the superior colliculus convert value signals into saccadic vigor.

Eye movements directed to high-valued objects in the environment are executed with greater vigor. Superior Colliculus (SC) - a subcortical structure that controls eye movements - contains multiple subtypes of neurons that have distinct functional roles in generating saccades. How does value-related information processed in other parts of the brain affect the responses of these different subtypes of SC neurons to facilitate faster saccades? To test this, we recorded four subtypes of neurons simultaneously while the monkey made saccades to objects they had been extensively trained to associate with large or small rewards (i.e., good or bad). In three subtypes of neurons (visual, visuomotor, and motor), the good objects elicited more spikes than bad objects. More importantly, using a bootstrapping procedure, we identified three separable phases of activity: 1) early visual response (EVIS), 2) late visual response (LVIS), and 3) pre-saccadic (PreSAC) motor response in these neuronal subtypes. In each subtype of neurons, the value of objects (good vs. bad) was positively correlated with the activity in the LVIS and PreSAC phases but not the EVIS phase. These data suggest that the value information from other brain regions modulates the visual (LVIS) and the motor (PreSAC) responses of visual, visuomotor, and motor neurons. This enhanced activation facilitates the faster initiation and execution of the saccade based on the value of each object. In addition, we found a novel class of tonically active neurons that decrease their activity in response to object onset and remain inhibited till the end of the saccade. We suggest that these tonic neurons facilitate the saccade to objects by disinhibiting the interactions between the other three SC neurons.

neuroscience↗

bioRxiv2025

In-situ diversification and regional attributes shape asymmetric diversity of Miliusa (Annonaceae) in tropical Asia.

AimWe examine biogeography and speciation patterns in Miliusa Lesch. ex A. DC. ([~]65 species) distributed in tropical Asia to understand the uneven distribution of its extant diversity. LocationTropical Asia TaxonMiliusa (Annonaceae) MethodsPhylogenetic reconstruction was performed using six plastid markers across 52 species using both ML and BI approaches. Divergence times were estimated using two fossil calibrations and an optimised relaxed clock, and ancestral areas were inferred with BioGeoBEARS. Speciation rates were examined using ClaDS and the DR statistic, and community structure was assessed using phylogenetic diversity metrics. ResultsMiliusa likely originated in the mid-Miocene, with Indo-Burma and peninsular India (PI) as its ancestral range. Its extant diversity is primarily attributed to in-situ speciation, with dispersal or vicariance playing limited but important roles in PI, and Wallacea and Sahul. Lineages in Indo-Burma began accumulating in the mid-Miocene, preceding those in PI ([~]10 Myr) and Wallacea and Sahul ([~]5 Myr). PI showed signs of lineage saturation and had lower speciation rates compared to Wallacea and Sahul and Indo-Burma, both of which had similar rates. All regions exhibited phylogenetic clustering, but Indo-Burma and PI differed in their sensitivity to phylogenetic depths. Main conclusionsThe uneven diversity of Miliusa is shaped by time for speciation, age, and dispersal, although their relative influence varies across regions. In Indo-Burma, long-term geo-climatic stability and greater niche availability likely facilitated the persistence of lineages, rapid speciation, and dispersal, making it an evolutionary hotspot for Miliusa. In contrast, PI exhibited lower richness and speciation rates despite being old, likely due to the contraction of wet habitats in the Miocene that limited available niches for speciation. Lineages in Wallacea and Sahul show typical island-like radiations, with speciation rates comparable to the larger and more geo-climatically stable Indo-Burma, despite their more recent origin. Overall, our results highlight the role of Miocene-driven climatic vicariance and Pliocene-Pleistocene climatic fluctuations in shaping the diversification dynamics and regional diversity patterns across tropical Asia.

evolutionary biology↗

bioRxiv2025

Spatial patterns of diversity in forest birds of peninsular India

Biodiversity is structured via complex interactions among ecological, geological, and climatic processes. Regions with high heterogeneity in climate and topography are known to harbor fine scale patterns in diversity which are often overlooked in global scale analyses. Here, we investigate spatial phylogenetic patterns of forest bird diversity across peninsular India, a region with high topographic and climatic heterogeneity. Using a comprehensive global bird phylogeny, we employ metrics such as Phylogenetic Diversity (PD), Phylogenetic Endemism (PE), and their relative forms (RPD, RPE) to quantify evolutionary history and endemism of forest birds in peninsular India. We examine the roles of contemporary climate, historic climatic stability, and topography in shaping these patterns. Our results reveal a strong gradient in diversity, with the southern Western Ghats acting as a major hotspot for both taxonomic and phylogenetic diversity and endemism. We detect distinct ecological and phylogenetic community structures across the peninsula, likely shaped by regional species pools and biogeographic barriers. Areas with greater topographic complexity, higher precipitation, and greater historic climatic stability were found to support high diversity. Our study provides critical insights for biogeography in this understudied yet highly biodiverse region for forest birds.

ecology↗

bioRxiv2025

Using aerial thermography to map terrestrial thermal environments in unprecedented detail

O_LIThe accurate quantification of thermal environments is crucial for predicting the impacts of climate change across ecosystems. C_LIO_LITwo major obstacles exist in mapping biologically relevant thermal landscapes: 1) overcoming the mismatch between the spatial resolution at which environmental data are typically collected and the scale at which a particular organism experiences thermal variation, and 2) quantifying thermal landscapes without substantial measurement gaps in time or space. C_LIO_LIWe present a new method that integrates aerial thermography from uncrewed aerial vehicles with field-deployed operative temperature models to generate fine-scale, spatiotemporally complete maps of operative temperature. C_LIO_LITo ensure the accessibility of our method, we developed an R package, throne, which streamlines the necessary corrections to raw drone data and produces operative thermal landscapes for any day or time during which data loggers were deployed. C_LIO_LIOur method allows researchers to generate detailed and biologically relevant thermal landscapes for species of interest which should enhance our understanding of animal thermal ecology and improve our ability to forecast the responses of organisms to environmental change. C_LI

ecology↗

bioRxiv2025

Effects of frugivore species pool and seed size on the diversity and functional composition of frugivores visiting fruiting trees

The relationship between biodiversity and ecosystem functioning in seed dispersal remains understudied despite its critical role in maintaining plant diversity in the tropics. Field studies on this relationship are often confounded by environmental and phylogenetic variations across species richness gradients. We examined how overall avian frugivore species richness at a site influenced the frugivore richness, visitation rates and functional composition of two key effect traitsbeak width and hand-wing indexon fruiting trees. Across six sites in tropical Asia, spanning a sevenfold gradient in frugivore species richness but with similar forest types and phylogenetically nested frugivore communities, we recorded 34,014 interactions between 134 avian frugivores and 131 plant species. Our results provide some support for the biodiversity-ecosystem functioning relationship, as higher overall frugivore species richness increased the number of frugivore species visiting individual fruiting trees but not the functional composition of frugivores. Seed size had a stronger influence on the frugivore species richness, visitation rates, and the beak size of visiting frugivores, highlighting the dominant role of morphological trait matching in influencing plant-frugivore interactions. Our findings suggest functional redundancy in certain aspects of seed dispersal effectiveness due to density compensation and the presence of key seed disperser lineages in species-poor sites.

ecology↗

bioRxiv2024

Image Correlation Spectroscopy is a Robust Tool to Quantify Cellular DNA Damage Response

The DNA Damage response (DDR) is both essential and highly complex. Evaluating the DDR is a critical aspect of cell biology. Counting DNA damage foci is one of the most common approaches to study the DDR. Yet, quantification of protein foci suffers from experimental limitations, subjectivity of analysis and is restricted to a handful of the hundreds of DDR proteins. Here we apply image correlation spectroscopy (ICS) to quantify the local clustering at sites of DNA damage directly. We found that ICS outperformed foci counting of traditional DDR markers and enabled quantification of other markers without the complex labeling procedures that are otherwise required. ICS analysis also provided insight into DDR protein recruitment that was previously undetectable. Further expansion incorporating analysis to cell cycle classification demonstrates a rapid, non-biased approach to fully study the DNA damage response within cells. ICS analysis presents an objective, quantitative image analysis technique to study the DNA damage response in unaltered cells that we expect will significantly enhance quantitative DNA damage response research.

cell biology↗

bioRxiv2024

Harmonising distributed tree inventory datasets across India can fill critical gaps in tropical ecology

AO_SCPLOWBSTRACTC_SCPLOWO_LIGlobal analyses of tree diversity and function are strongly biased geographically, with poor representation from forests of the Indian subcontinent. Even though data from India - representing two-thirds of the subcontinent and spanning a wide range of tree-based biomes - exists, a barrier to syntheses is the absence of accessible and standardised data. Further, with increasing human footprint across ecosystems, data from Indian landscapes, with their long history of human-nature interactions is a key link to understand the future of tropical forested landscapes. Given the long history of human-nature interactions and high human footprint in the region, accessible and standardized data from the subcontinent can enable understanding the future of tropical landscapes under increasing human footprints globally. C_LIO_LICombining literature searches with manual data retrieval, we assembled the INdia Tree Inventory dataset, INvenTree. INvenTree is the largest meta-dataset of peer-reviewed publications (n = 465) from 1991-2023 on geolocated plot-based tree inventories of multispecies communities from Indian ecosystems, in aggregate covering 4653.64 ha and all of its woody biomes. C_LIO_LIUsing INvenTree, we show extensive sampling across tropical moist and dry forests, the dominant ecosystem types in the country. However, most studies have low sampling effort (median sampled area = 2 ha) and data across studies is not openly accessible (73.33 % of studies representing 83.43% of the sampled area), potentially hindering inclusion into regional or global syntheses. C_LIO_LISignificantly, we show majority authorship from within the country; 82.8% of corresponding authors were from India and 73.33% of the studies had all authors affiliated with Indian institutions. We also identify ecological and conservation sampling priority regions based on forest cover and forest loss and set a blueprint for future sampling efforts in the country. C_LIO_LIBased on extensive Indian scholarship in forest ecology showcased through the INvenTree dataset, we see opportunity for regional collaboration to create scientific inferences that are larger and scalable, while prioritising data and knowledge equity. Harmonising these existing datasets, and synthesising historic and grey literature, will contribute enormously to understanding the human dimension of tropical ecology as well as informing regional management and conservation. C_LI

ecology↗

bioRxiv2024

DEEP LEARNING APPROACH FOR RENAL CELL CARCINOMA DETECTION,SUBTYPING, AND GRADING

We propose a comprehensive end-to-end pipeline designed for the detection, subtyping, and grading of tumors. Our proposed method-ology initiates the generation of a heat map, indicating the severity of the tumor. Subsequently, the identification of the most critical patches is conducted based on the probability scores. These identified patches are then directed to a grade prediction network. A distinctive aspect of our research lies in being the first to explore an end-to-end pipeline for both heat map generation and grading prediction. Our experiments were conducted leveraging the public, The Cancer Genome Atlas (TCGA) repository, focusing specifically on renal cancer. We introduced additional patch-level labels to improve the model performance. The generation of tumor heat maps targeted three primary cancer subtypes: clear cell, papillary, and chromophobe. To enhance our approach, we implemented center-loss and introduced a method aimed at refining the quality of patches. The experimental outcomes highlight superior performance compared to state-of-the-art method. This research contributes to the advancement of tumor detection and grading, emphasizing the significance of an integrated approach for heat map generation and grading pre-diction.

bioinformatics↗

bioRxiv2023

Virus-like DNA tracers for characterizing wastewater-based pathogen monitoring systems

Wastewater-based pathogen monitoring has recently become a ubiquitous method for tracking the abundance and evolution of pathogens in a community or port of entry. But accurate inference of disease incidence from wastewater remains challenging, in large part due to noise and bias arising from wastewater transport and measurement. We developed a new system of tracer particles designed to enhance wastewater monitoring of viral pathogens. These tracers, which consist of synthetic DNA barcodes packaged into non-infectious viral capsids, can be deposited at known amounts and times into the sewer system and measured in wastewater samples to assess features such as assay sensitivity, and the decay and delay in viral signal arising from a shedding event. Here we describe the design, construction, and initial characterization of a 25-plex tracer library. Our tracer library supports simultaneous measurement of up to 5 distinct tracers by qPCR and up to 25 distinct tracers by amplicon or metagenomic sequencing. We demonstrate experimentally that the tracers are biologically inert and exhibit good stability and qPCR-assay performance in wastewater. These features collectively suggest that barcoded, virus-like tracers have the required properties for high-accuracy, high-resolution characterization of wastewater monitoring systems.

synthetic biology↗

bioRxiv2023

Frugivory and seed predation of fishtail palm (Caryota mitis Lour.) on the remote oceanic island of Narcondam, India

Oceanic islands, due to their evolutionary history and isolation, hold a disproportionately high proportion of endemic species. However, their evolutionary history also makes them vulnerable to extinctions, with most known extinctions occurring on islands. Plant-animal interactions are particularly important on islands, as island systems generally have low redundancy and are more vulnerable to disruption either via extinction or by invasive species. Here, we examined the fruit removal and seed predation of a keystone palm, Caryota mitis, on the remote oceanic island of Narcondam. The island endemic Narcondam hornbill (Rhyticeros narcondami), was the sole seed disperser of the Caryota mitis (90 hours; N = 15 trees), indicating a lack of redundancy in seed dispersal of the palm on this island. While the invasive rodent, Rattus cf. tiomanicus was the sole predator of the Caryota mitis seeds in the forest (N = 15 individual fruiting palms, 416 trap nights). Overall, 17.1% of the seeds placed (N = 375 seeds) were removed. Seeds placed under and away from the canopy, and at different densities (2 plots with 10 seeds each; 1 plot with 5 seeds, respectively), showed similar removal rates. This is indicative of ambient seed predation and the lack of safe sites for the regeneration of Caryota mitis, with potential deleterious effects on the subsequent stages of the "seed dispersal cycle". Here, from a data deficient site, we provide baseline information on the plant-frugivore interaction of a keystone palm and the potential impacts by an invasive rodent.

ecology↗

bioRxiv2022

Range restricted old and young lineages show the southern Western Ghats to be both museum and cradle of diversity for woody plants

The Western Ghats (WG) mountain chain is a global biodiversity hotspot with high diversity and endemicity of woody plants. The latitudinal breadth of the WG offers an opportunity to determine the evolutionary drivers of latitudinal diversity patterns. We examined the spatial patterns of evolutionary diversity using complementary phylogenetic diversity and endemism measures. To examine if different regions of the WG serve as a museum or cradle of evolutionary diversity, we examined the distribution of 470 species based on distribution modelling and occurrence locations across the entire region. In accordance with the expectation, we found that the southern WG is both a museum and cradle of woody plant evolutionary diversity, as a higher proportion of both old and young evolutionary lineages are restricted to the southern WG. The diversity gradient is likely driven by high geo-climatic stability in the south and phylogenetic niche conservatism for moist and aseasonal sites. This is corroborated by persistent lineage nestedness at almost all evolutionary depths (10-135 million years), and a strong correlation of evolutionary diversity with drought seasonality, precipitation and topographic heterogeneity. Our results highlight the global value of the WG, demonstrating, in particular, the importance of protecting the southern WG - an engine of plant diversification and persistence.

evolutionary biology↗

bioRxiv2020

A velocity plan with internal feedback control best explains modulation of saccade kinematics during eye-hand coordination.

Fast movements like saccadic eye movements that occur in the absence of sensory feedback are often thought to be under internal feedback control. In this framework, a desired input in the form of desired displacement signal is widely believed to be encoded in a spatial map of the superior colliculus (SC). This is then converted into a dynamic velocity signal that drives the oculomotor neurons. However, recent evidence has shown the presence of a dynamic signal within SC neurons, which correlates with saccade velocity. Hence, we used models based on optimal control theory to test whether saccadic execution could be achieved by a velocity based internal feedback controller. We compared the ability of a trajectory control model based on velocity to that of an endpoint control model based on final displacement to capture saccade behavior of modulation of peak saccade velocity by the hand movement, independent of the saccade amplitude. The trajectory control model tracking the desired velocity in optimal feedback control framework predicted this saccade velocity modulation better than an endpoint control model. These results suggest that the saccadic system has the flexibility to incorporate a velocity plan based internal feedback control that is imposed by task context. NEW & NOTEWORTHYWe show that the saccade generation system may use an explicit velocity tracking controller when demand arises. Modulation of peak saccade velocity due to modulation of the velocity of the accompanying hand movement was better captured using a velocity tracking stochastic optimal control model compared to an endpoint model of saccade control. This is the first evidence of trajectory planning and control for the saccadic system based on optimal control theory.

neuroscience↗