About

Vivek Venkatachalam is an Assistant Professor affiliated with the Bioengineering department at Northeastern University College of Engineering. His research focuses on Experimental Biophysics. He is based at the 335 ISEC building located at 360 Huntington Avenue, Boston, Massachusetts. Further details about his biography or specific research contributions are not provided on the page.

Research topics

• Neuroscience
• Biology
• Psychology
• Genetics
• Cognitive psychology

Selected publications

• Author Reply to Peer Reviews of Programmed Cell Death Modifies Neural Circuits and Tunes Intrinsic Behavior

  2026-04-19

  peer-review
  PublisherDOI

• <b>A</b><b>n enteric neuron-expressed variant ionotropic receptor detects ingested salt to regulate salt stress resistance</b>

  Open MIND · 2026-02-04 · 1 citations

  dataset

  The detection of internal chemicals by interoceptive chemosensory pathways is critical for regulating metabolism and physiology. The molecular identities of interoceptors, and the functional consequences of chemosensation by specific interoceptive neurons remain to be fully described. The <i>C. elegans</i> pharyngeal neuronal network is anatomically and functionally homologous to the mammalian enteric nervous system (Albertson et al., 1976; Cook et al., 2020). Here, we show that the I3 pharyngeal enteric neuron responds to cations via an I3-specific variant ionotropic receptor (IR) to regulate salt stress tolerance. The GLR-9 IR, located at the gut lumen-exposed sensory end of I3, is necessary and sufficient for salt sensation, establishing a chemosensory function for IRs beyond insects. Salt detection by I3 protects specifically against high salt stress, as <i>glr-9</i> mutants show reduced tolerance of hypertonic salt but not sugar solutions, with or without prior acclimation. While cholinergic signaling from I3 promotes tolerance to acute high salt stress, peptidergic signaling from I3 during acclimation is essential for resistance to a subsequent high salt challenge. Transcriptomic analyses show that I3 regulates salt tolerance in part via regulating the expression of osmotic stress response genes in distal tissues. Our results highlight the mechanisms by which chemosensation mediated by a defined enteric neuron regulates physiological homeostasis in response to a specific abiotic stress.

  DOI

• <b>A</b><b>n enteric neuron-expressed variant ionotropic receptor detects ingested salt to regulate salt stress resistance</b>

  Figshare · 2026-02-04

  datasetOpen access

  The detection of internal chemicals by interoceptive chemosensory pathways is critical for regulating metabolism and physiology. The molecular identities of interoceptors, and the functional consequences of chemosensation by specific interoceptive neurons remain to be fully described. The <i>C. elegans</i> pharyngeal neuronal network is anatomically and functionally homologous to the mammalian enteric nervous system (Albertson et al., 1976; Cook et al., 2020). Here, we show that the I3 pharyngeal enteric neuron responds to cations via an I3-specific variant ionotropic receptor (IR) to regulate salt stress tolerance. The GLR-9 IR, located at the gut lumen-exposed sensory end of I3, is necessary and sufficient for salt sensation, establishing a chemosensory function for IRs beyond insects. Salt detection by I3 protects specifically against high salt stress, as <i>glr-9</i> mutants show reduced tolerance of hypertonic salt but not sugar solutions, with or without prior acclimation. While cholinergic signaling from I3 promotes tolerance to acute high salt stress, peptidergic signaling from I3 during acclimation is essential for resistance to a subsequent high salt challenge. Transcriptomic analyses show that I3 regulates salt tolerance in part via regulating the expression of osmotic stress response genes in distal tissues. Our results highlight the mechanisms by which chemosensation mediated by a defined enteric neuron regulates physiological homeostasis in response to a specific abiotic stress.

  PublisherDOI

• The <i>C. elegans</i> nervous system reads the internal state of the hydrogen peroxide-detoxification machinery to trigger escape from this common reactive chemical

  bioRxiv (Cold Spring Harbor Laboratory) · 2026-01-24

  articleOpen access

  Hydrogen peroxide (H 2 O 2 ) is the most common reactive chemical threat faced by organisms. Here, we map the neural circuit that drives chemotactic escape from environmental H 2 O 2 in the nematode C. elegans . Twenty-four neuron classes with sensory endings at the mouth and nose of the animal detect H 2 O 2 . Their response dynamics encode stimulus intensity and exposure history, and their partial redundancy makes avoidance resilient to the loss of individual inputs. Sensing begins when H 2 O 2 oxidizes the peroxidatic and resolving cysteines of the cytosolic peroxiredoxin PRDX-2, which relays this oxidative signal to cysteines on the LITE-1 and GUR-3 ion channels, triggering calcium influx in sensory neurons that drive escape. Most of these neurons release glutamate to drive H 2 O 2 -dependent excitation of AIA interneurons, whereas others signal through non-glutamatergic routes, providing multiple routes for signal transmission. Thus, the C. elegans nervous system acts as a hydrogen peroxide sentinel that monitors H 2 O 2 -induced changes in the intracellular H 2 O 2 -detoxification machinery and relays them to interneurons driving organism-wide escape. This raises the possibility that circuit defects in aging and neurodegenerative disease arise from altered peroxiredoxin-mediated H 2 O 2 signaling rather than primarily from direct macromolecular damage.

  PublisherOA PDFDOI

• An enteric neuron ionotropic receptor regulates salt stress resistance

  Nature · 2026-04-01 · 1 citations

  articleOpen access

  The detection of internal chemicals by interoceptive chemosensory pathways is critical for regulating metabolism and physiology1. The molecular identities of interoceptors, and the functional consequences of chemosensation by specific interoceptive neurons, remain to be fully described. The pharyngeal neuronal network of Caenorhabditis elegans is anatomically and functionally analogous to the mammalian enteric nervous system2,3. Here we show that the I3 pharyngeal enteric neuron responds to cations via an I3-specific ionotropic receptor to regulate salt stress tolerance. The GLR-9 ionotropic receptor and the GLR-7 IR25a co-receptor orthologue localize to the gut lumen-exposed sensory ending of I3, and are necessary and sufficient for salt sensation. Salt detection by I3 protects specifically against high-salt stress, as glr-9 mutants show reduced tolerance of hypertonic salt but not of sugar solutions, with or without prior acclimatization. Whereas cholinergic signalling from I3 promotes tolerance of acute high-salt stress, peptidergic signalling from I3 during acclimatization is essential for resistance to a subsequent high-salt challenge. Transcriptomic and reporter gene analyses show that I3 modulates salt tolerance in part by regulating the expression of salt stress response genes in distal tissues. Correspondingly, mutations in a subset of salt- and GLR-9-regulated genes reduce salt stress resistance. Our results describe the mechanisms by which chemosensation mediated by a defined enteric neuron regulates physiological homeostasis in response to a specific abiotic stress. The I3 pharyngeal enteric neuron in Caenorhabditis elegans detects high-salt conditions, and the GLR-9 ionotropic salt receptor expressed specifically in I3 regulates genes related to salt stress resistance in distal tissues.

  PublisherDOI

• Neuronal Activity Regulating the Dauer Entry Decision in <i>Caenorhabditis elegans</i>

  eNeuro · 2025-12-26

  articleOpen access

  involves a choice between two alternative developmental trajectories. Hermaphroditic larvae can either become reproductive adults or, under conditions of crowding or low food availability, enter a long-term, stress-resistant diapause known as the dauer stage. Chemical signals from a secreted larval pheromone promote the dauer trajectory in a concentration-dependent manner, and their influence can be antagonized by increased availability of a microbial food source. The decision is known to be under neuronal control, involving both sensory and interneurons. However, little is known about the dynamics of the underlying circuit, and the circuit mechanisms by which short-term fluctuations in the ratio of food and pheromone experienced by individual larvae are remembered and averaged over several hours. To investigate this, we quantitatively characterized the neuronal responses to food and pheromone inputs by measuring calcium traces from ASI and AIA neurons, each of which has previously been implicated in regulation of dauer entry. We found that calcium in ASI increases linearly in response to food and similarly decreases in response to pheromone. Notably, the ASI response persists well beyond removal of the food stimulus, thus encoding a memory of recent food exposure. In contrast, AIA reports instantaneous food availability and is unaffected by pheromone. We discuss how these findings may inform our understanding of this long-term decision-making process.

  PublisherOA PDFDOI

• Whole-brain chemosensory responses of both <i>C. elegans</i> sexes

  bioRxiv (Cold Spring Harbor Laboratory) · 2025-05-19 · 3 citations

  preprintOpen accessSenior authorCorresponding

  Sexually-dimorphic neural circuits play a critical role in shaping sex-specific animal behaviors. Maps of the structural dimorphisms in these circuits have been explored by analyzing “synaptic connectomes”, electron micrograph reconstructions of synaptic connectivity. Nevertheless, recent studies in the model organism C. elegans have shown little to no correlation between the synaptic connectome and dynamic neural activity. Therefore, the extent of sexual dimorphism in functional neural activity remains unknown. To determine the extent of functional sexual-dimorphisms in C. elegans we compared activity, neuron-by-neuron, across all neurons in the heads of both sexes. To sample a broad view of responses to different sensory modalities, we tested a diverse panel of ethologically-relevant olfactory, gustatory, and chemical stimuli, representing both attractive and aversive cues. We found that nearly every sensory neuron responded dimorphically to at least one cue and monomorphically to other cues, indicating that sexually-dimorphic circuits are pervasive and stimulus dependent. This dimorphic and monomorphic activity was present to a lesser extent in downstream interneurons and even less so in motoneurons, implicating sensory neurons as the primary source and location of sexually-dimorphic activity. Comparing the functional activity we measured to the published synaptic connectomes of both sexes revealed that sexual dimorphism in functional connectivity was distinct from and complementary to sexual dimorphism in synaptic connectivity. Our results provide a first-of-its-kind comparison of whole-brain dynamics between sexes at the level of single neurons, serving as an extensive resource for further investigations of functional sex differences.

  PublisherOA PDFDOI

• Widefield Targeted Illumination Microscopy Enables Optically‐Sectioned, Motion‐Resilient Imaging of Neuronal Fibers and Their Dynamics

  Laser & Photonics Review · 2025-10-06

  articleOpen access

  Abstract In widefield fluorescence imaging of neurons, out‐of‐focus and scattered light from the bright cell body often obscures nearby dim fibers and degrades their contrast. Scanning techniques can solve this problem but are limited by reduced imaging speed and increased cost. In this study, stray light in widefield imaging is greatly reduced by modulating the illumination intensity to different structures. An iterative approach is used to identify fibers by real‐time image processing and target illumination to fibers by a digital micromirror device add‐on to a common widefield microscope. Bright cell bodies are illuminated with minimal light intensity, and in‐focus fibers with high light intensity. This procedure minimizes the background and enhances the visibility of fibers while maintaining a fast imaging speed, low photobleaching rate, and low cost. By updating the targeting pattern, illumination is maintained on the structures of interest, even in moving samples. Using this targeted illumination approach, high contrast, optically sectioned imaging of complex neurons is demonstrated in anesthetized C. elegans , ex vivo mouse brain slice, and restrained zebrafish larva, as well as high‐speed imaging of dynamic changes in C. elegans .

  PublisherOA PDFDOI

• Sensory integration of food availability and population density during the diapause exit decision involves insulin-like signaling in <i>Caenorhabditis elegans</i>

  bioRxiv (Cold Spring Harbor Laboratory) · 2024-03-25 · 2 citations

  preprintOpen access

  Abstract Decisions made over long time scales, such as life cycle decisions, require coordinated interplay between sensory perception and sustained gene expression. The Caenorhabditis elegans dauer (or diapause) exit developmental decision requires sensory integration of population density and food availability to induce an all-or-nothing organismal-wide response, but the mechanism by which this occurs remains unknown. Here, we demonstrate how the ASJ chemosensory neurons, known to be critical for dauer exit, perform sensory integration at both the levels of gene expression and calcium activity. In response to favorable conditions, dauers rapidly produce and secrete the dauer exit-promoting insulin-like peptide INS-6. Expression of ins-6 in the ASJ neurons integrate population density and food level and can reflect decision commitment since dauers committed to exiting have higher ins-6 expression levels than those of non-committed dauers. Calcium imaging in dauers reveals that the ASJ neurons are activated by food, and this activity is suppressed by pheromone, indicating that sensory integration also occurs at the level of calcium transients. We find that ins-6 expression in the ASJ neurons depends on neuronal activity in the ASJs, cGMP signaling, a CaM-kinase pathway, and the pheromone components ascr#8 and ascr#2. We propose a model in which decision commitment to exit the dauer state involves an autoregulatory feedback loop in the ASJ neurons that promotes high INS-6 production and secretion. These results collectively demonstrate how insulin-like peptide signaling helps animals compute long-term decisions by bridging sensory perception to decision execution. Summary/Significance Statement Animals must respond appropriately to multiple sensory stimuli to make informed decisions. It remains unclear how the nervous system is able to integrate different sensory cues and propagate that information towards making decisions over longer timescales. We use the nematode Caenorhabditis elegans to investigate how sensory integration occurs during the decision to exit diapause, a stress-resistant developmentally arrested state triggered by multiple sensory inputs including food availability and population density. We show how expression of an insulin-like peptide critical to dauer exit reflects the sensory integration process and decision commitment, and we dissect the regulation of this insulin-like peptide’s expression. Our study explicitly analyzes the relationship between neuronal activity and neuropeptide expression during a complex decision with diverse sensory inputs.

  PublisherOA PDFDOI

• Neuron tracking in C. elegans through automated anchor neuron localization and segmentation

  2024-01-26 · 4 citations

  articleSenior author

  Tracking fluorescent objects through movies is a critical first step in quantifying electrical or molecular dynamics in cells. In many applications, it is necessary to track large numbers of fluorescent objects moving through tissue in a nonrigid manner. In this submission, we describe the use of a graph attention-based neural network to detect-and-link fluorescent neuronal nuclei in the brain of freely behaving worms (<i>C. elegans</i>). This approach allows us to reliably match on average 33% of the cells. When combined with a nonrigid registration algorithm that can leverage partial matches, this approach allows efficient tracking of all cells with substantially less manual intervention. Further work is needed to integrate this into previous registration pipelines.

  PublisherDOI

Recent grants

• NSF Postdoctoral Fellowship in Biology FY 2013

  NSF · $138k · 2013–2015

Frequent coauthors

• Aravinthan D. T. Samuel

  Harvard University Press

  26 shared

• Mei Zhen

  Mount Sinai Hospital

  25 shared

• Wesley Hung

  Lunenfeld-Tanenbaum Research Institute

  21 shared

• Albert Lin

  Princeton University

  14 shared

• Min Wu

  13 shared

• Anne C. Hart

  University of Illinois Urbana-Champaign

  13 shared

• Huiyan Huang

  Guangdong General Hospital

  12 shared

• Heather Bennett

  Trinity College

  12 shared

Education

• Postdoctoral Fellow, Physics

  Harvard University

  2017

• Ph.D., Physics

  Harvard University

  2012

• S.B., Physics

  Massachusetts Institute of Technology

  2006

• S.B., Electrical Science and Engineering

  Massachusetts Institute of Technology

  2006