Biology subjects

Narayan, L.

Publications and source records attributed to Narayan, L..

5 recordsLinked to original sources

bioRxiv2026

Genomic Footprints of Bottlenecks, Isolation, and Inbreeding: A Case Study of Two Vulture Cohorts in India

Genomic erosion as a manifestation of small effective population size (Ne) and consanguinity subverts long-term perpetuation of threatened species by compromising their adaptive potential; however, the integration of genomics remains limited in applied conservation efforts to guide priorities. This study combines non-invasive sampling, double-digest Restriction site-associated DNA sequencing (ddRAD), and population-genomic analyses to assess genetic health in two vulture assemblages-mixed wild enclosure and captive breeding cohorts. Both the geographical locations exhibit signs of populations in distress: low genetic diversity and abundant intermediate-length runs of homozygosity (RoH), consistent with long-term reduced Ne plus recent demographic isolation. Our demographic model runs favoured ancient migration (AM) topology characterised by an ephemeral window of gene flow, taken over by a prolonged population separation period. The mutation quantification results from approximately 59,000 outgroup-polarised SNPs reveal higher additive burden and more homozygous-derived sites in BKN. However, this was later traced to low-impact and non-coding variants rather than a surge in the loss-of-function (LoF) alleles. The data support a genomic profile that carries an elevated risk from polygenic/aggregate deleterious burden in BKN despite a scarcity of high-impact mutations. By highlighting the disconnect between genetic resilience and demographic recovery, our results accentuate the need to incorporate genomics-informed inbreeding and monitoring programs, while also focusing on reducing anthropogenic mortality with genetic augmentation.

genomics↗

bioRxiv2024

A global dopaminergic learning rate enables adaptive foraging across many options

In natural environments, animals must efficiently allocate their choices across multiple concurrently available resources when foraging, a complex decision-making process not fully captured by existing models. To understand how rodents learn to navigate this challenge we developed a novel paradigm in which untrained, water-restricted mice were free to sample from six options rewarded at a range of deterministic intervals and positioned around the walls of a large ([~]2m) arena. Mice exhibited rapid learning, matching their choices to integrated reward ratios across six options within the first session. A reinforcement learning model with separate states for staying or leaving an option and a dynamic, global learning rate was able to accurately reproduce mouse learning and decision-making. Fiber photometry recordings revealed that dopamine in the nucleus accumbens core (NAcC), but not dorsomedial striatum (DMS), more closely reflected the global learning rate than local error-based updating. Altogether, our results provide insight into the neural substrate of a learning algorithm that allows mice to rapidly exploit multiple options when foraging in large spatial environments.

neuroscience↗

bioRxiv2024

Song Torrent: A modular, open-source 96-chamber audio and video recording apparatus with optogenetic activation and inactivation capabilities for Drosophila

BackgroundO_LIMany Drosophila species use acoustic communication during courtship and studies of these communication systems have provided insight into neurobiology, behavioral ecology, ethology, and evolution. C_LIO_LIRecording Drosophila courtship sounds and associated behavior is challenging, especially at high throughput, and previously designed devices are relatively expensive and complex to assemble. C_LI ResultsO_LIWe present construction plans for a modular system utilizing mostly off-the-shelf, relatively inexpensive components that provides simultaneous high-resolution audio and video recording of 96 isolated or paired Drosophila individuals. C_LIO_LIWe provide open-source control software to record audio and video. C_LIO_LIWe designed high intensity LED arrays that can be used to perform optogenetic activation and inactivation of labelled neurons. C_LIO_LIThe basic design can be modified to facilitate novel study designs or to record insects larger than Drosophila. C_LIO_LIFewer than 96 microphones can be used in the system if the full array is not required or to reduce costs. C_LI ImplicationsO_LIOur hardware design and software provide an improved platform for reliable and comparatively inexpensive high-throughput recording of Drosophila courtship acoustic and visual behavior and perhaps for recording acoustic signals of other small animals. C_LI

animal behavior and cognition↗

bioRxiv2023

Low-latency extracellular spike assignment for high-density electrodes at single-neuron resolution

Real-time neural signal processing is essential for brain-machine interfaces and closed-loop neuronal perturbations. However, most existing applications sacrifice cell-specific identity and temporal spiking information for speed. We developed a hybrid hardware-software system that utilizes a Field Programmable Gate Array (FPGA) chip to acquire and process data in parallel, enabling individual spikes from many simultaneously recorded neurons to be assigned single-neuron identities with 1-millisecond latency. The FPGA assigns labels, validated with ground-truth data, by comparing multichannel spike waveforms from tetrode or silicon probe recordings to a spike-sorted model generated offline in software. This platform allowed us to rapidly inactivate a region in vivo based on spikes from an upstream neuron before these spikes could excite the downstream region. Furthermore, we could decode animal location within 3 ms using data from a population of individual hippocampal neurons. These results demonstrate our systems suitability for a broad spectrum of research and clinical applications.

neuroscience↗

bioRxiv2021

Serotonergic neurons mediate operant conditioning in Drosophila larvae

Observed across species, operant conditioning facilitates learned associations between behaviours and outcomes, biasing future action selection to maximise reward and avoid punishment. To elucidate the underlying neural mechanisms, we built a high-throughput tracker for Drosophila melanogaster larvae, combining real-time behaviour detection with closed-loop optogenetic and thermogenetic stimulation capabilities. We demonstrate operant conditioning in Drosophila larvae by inducing a bend direction preference through optogenetic activation of reward-encoding serotonergic neurons. Specifically, we establish that the ventral nerve cord is necessary for this memory formation. Our results extend the role of serotonergic neurons for learning in insects as well as the existence of learning circuits outside the mushroom body. This work supports future studies on the function of serotonin and the mechanisms underlying operant conditioning at both circuit and cellular levels.

neuroscience↗